### Setup Task Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rake-task.md

Example command to run the setup task directly.

```bash
bundle exec rake active_record_doctor:setup
```

--------------------------------

### Constructor Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rake-task.md

Example of how to instantiate the Rake::Task with custom dependencies, configuration path, and setup proc.

```ruby
ActiveRecordDoctor::Rake::Task.new do |task|
  task.deps = [:environment]
  task.config_path = Rails.root.join(".active_record_doctor.rb")
  task.setup = -> { Rails.application.eager_load! }
end
```

--------------------------------

### Custom Dependencies Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rake-task.md

Example demonstrating how to configure the ActiveRecordDoctor::Rake::Task with custom dependencies and setup logic.

```ruby
require "active_record_doctor"

task :load_database do
  # Custom database loading logic
  puts "Loading database..."
end

ActiveRecordDoctor::Rake::Task.new do |task|
  task.deps = [:environment, :load_database]
  
  task.setup = -> do
    Rails.application.eager_load!
    # Additional setup
    puts "Setup complete"
  end
end
```

--------------------------------

### Load Configuration with Defaults Example (Defaults Only)

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/config.md

Example of loading only default configuration.

```ruby
# Use only defaults
config = ActiveRecordDoctor.load_config_with_defaults(nil)
```

--------------------------------

### Load Configuration Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/config.md

Example of loading configuration, with error handling for missing files.

```ruby
begin
  config = ActiveRecordDoctor.load_config(".active_record_doctor.rb")
rescue ActiveRecordDoctor::Error::ConfigurationFileMissing
  puts "Configuration file not found. Using defaults instead."
  config = ActiveRecordDoctor.load_config_with_defaults(nil)
end
```

--------------------------------

### Merge Configuration Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/config.md

Example of merging default and user configurations.

```ruby
default = ActiveRecordDoctor.load_config(ActiveRecordDoctor::Config::DEFAULT_CONFIG_PATH)
user = ActiveRecordDoctor.load_config(".active_record_doctor.rb")
final = default.merge(user)
```

--------------------------------

### Get All Available Detectors

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Ruby code to iterate through all available detectors in ActiveRecordDoctor and print their names and descriptions.

```ruby
ActiveRecordDoctor.detectors.each do |name, detector_class|
  puts "#{name}: #{detector_class.description}"
end
```

--------------------------------

### Missing Foreign Keys Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Example of a missing foreign key constraint.

```ruby
class Post < ApplicationRecord
  belongs_to :user
  # Column: user_id exists
  # No foreign key constraint!
end
```

--------------------------------

### ConfigurationFileMissing Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/errors.md

Example of loading a non-existent configuration file.

```ruby
config = ActiveRecordDoctor.load_config("/nonexistent/.active_record_doctor.rb")
# => ActiveRecordDoctor::Error::ConfigurationFileMissing
```

--------------------------------

### Load Configuration with Defaults Example (Merged)

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/config.md

Example of loading defaults merged with user configuration.

```ruby
# Use defaults merged with user config
config = ActiveRecordDoctor.load_config_with_defaults(".active_record_doctor.rb")
```

--------------------------------

### Configure Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/config.md

Example of configuring active_record_doctor with global and detector settings.

```ruby
ActiveRecordDoctor.configure do
  global :ignore_tables, ["ar_internal_metadata", "schema_migrations"]
  
  detector :missing_presence_validation,
    enabled: true,
    ignore_models: ["User"],
    ignore_attributes: ["Post.excerpt"],
    ignore_columns_with_default: true
end
```

--------------------------------

### Example usage of postgresql? method

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/utilities.md

Example of how to use the postgresql? method to conditionally execute SQL.

```ruby
if ActiveRecordDoctor::Utils.postgresql?
  # Use PostgreSQL-specific SQL
  connection.execute("SELECT pg_size_pretty(pg_total_relation_size('users'))")
else
  # Use generic SQL or adapter-specific approach
end
```

--------------------------------

### Configuration File Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/configuration.md

Example of how to configure ActiveRecordDoctor in a `.active_record_doctor.rb` file.

```ruby
# .active_record_doctor.rb
ActiveRecordDoctor.configure do
  # Global settings
  global :setting_name, value
  
  # Detector-specific settings
  detector :detector_name,
    setting1: value,
    setting2: value
end
```

--------------------------------

### Missing Unique Index Example: Basic

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Example of a basic missing unique index problem.

```ruby
class User < ApplicationRecord
  validates :email, uniqueness: true
  # No unique index on email!
end
```

--------------------------------

### Example of Help Text Output

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/utilities.md

An example of the actual output from generating help text for a specific detector.

```text
# Output:
# missing_presence_validation - detect non-NULL columns without a corresponding presence validator
#
# Configuration options:
#   - enabled (local only) - set to false to disable the detector altogether
#   - ignore_models (local and global) - models whose underlying tables' columns should not be checked
#   - ignore_attributes (local only) - specific attributes, written as Model.attribute, that should not be checked
#   - ignore_columns_with_default (local only) - ignore columns with default values, should be provided as boolean
```

--------------------------------

### Main Detection Task Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rake-task.md

Example command to run a specific detector task.

```bash
bundle exec rake active_record_doctor:missing_foreign_keys
bundle exec rake active_record_doctor:extraneous_indexes
```

--------------------------------

### Help Task Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rake-task.md

Example command to run the help task for a specific detector and its expected output.

```bash
bundle exec rake active_record_doctor:missing_presence_validation:help
# Output:
# missing_presence_validation - detect non-NULL columns without a corresponding presence validator
#
# Configuration options:
#   - enabled (local only) - set to false to disable the detector altogether
#   - ignore_models (local and global) - models whose underlying tables should not be checked
#   - ignore_attributes (local only) - specific attributes, written as Model.attribute, that should not be checked
#   - ignore_columns_with_default (local only) - ignore columns with default values, should be provided as boolean
```

--------------------------------

### Input File Format Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/generators.md

Example of the expected format for the input file containing index suggestions.

```text
add an index on users(account_id) - consider adding an index on the foreign key
add an index on posts(user_id) - consider adding an index on the foreign key
add an index on comments(post_id, user_id) - consider adding an index on the foreign key
```

--------------------------------

### Unindexed Foreign Keys Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Example of a belongs_to association with a foreign key column that lacks an index.

```ruby
class Post < ApplicationRecord
  belongs_to :user
  # Generates: user_id column (foreign key)
  # No index on user_id!
end
```

--------------------------------

### Missing Unique Index Example: Scoped

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Example of a scoped uniqueness validation problem.

```ruby
class Tag < ApplicationRecord
  validates :name, uniqueness: { scope: :project_id }
  # No unique index on (name, project_id)!
end
```

--------------------------------

### Obtaining Help for a Specific Detector

Source: https://github.com/gregnavis/active_record_doctor/blob/master/README.md

Example of how to get help for a specific detector, showing supported configuration options.

```bash
bundle exec rake active_record_doctor:extraneous_indexes:help
```

--------------------------------

### Incorrect Boolean Presence Validation Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Example of an incorrect presence validator on a boolean column.

```ruby
class User < ApplicationRecord
  validates :active, presence: true
  # active is a boolean column
  # presence: true is ineffective!
end
```

--------------------------------

### Automatic Configuration File Discovery Examples

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rake-task.md

Examples demonstrating the legacy and recommended configuration file naming conventions.

```ruby
# Deprecated - shows warning
.active_record_doctor

# Recommended
.active_record_doctor.rb
```

--------------------------------

### Example Generated Migration

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/generators.md

A concrete example of a migration file generated for adding indexes.

```ruby
class IndexForeignKeysInUsers < ActiveRecord::Migration[7.0]
  def change
    add_index :users, [:account_id]
    add_index :users, [:organization_id]
  end
end

class IndexForeignKeysInPosts < ActiveRecord::Migration[7.0]
  def change
    add_index :posts, [:user_id]
  end
end
```

--------------------------------

### Example: Running all detectors

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/runner.md

Demonstrates how to run all detectors and exit with an error code if any problems are found.

```ruby
success = runner.run_all
exit(1) unless success
```

--------------------------------

### Example workflow

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rails-integration.md

Example workflow for generating migrations for missing indexes.

```bash
# 1. Run unindexed_foreign_keys detector
bundle exec rake active_record_doctor:unindexed_foreign_keys > /tmp/missing_indexes.txt

# 2. Generate migrations
rails generate active_record_doctor:add_indexes /tmp/missing_indexes.txt

# 3. Review migrations
ls db/migrate/*index_foreign_keys*.rb

# 4. Run migrations
rails db:migrate
```

--------------------------------

### Example invalid input

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/generators.md

Examples of malformed input lines that would trigger an error.

```text
this line is malformed
add an index on invalid syntax
```

--------------------------------

### Show Help for a Detector

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Ruby code to retrieve a specific detector and generate its help information.

```ruby
detector = ActiveRecordDoctor.detectors[:missing_presence_validation]
help = ActiveRecordDoctor::Help.new(detector)
puts help
```

--------------------------------

### Problem 2: Circular delete relationships

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Example illustrating a potential problem with circular `dependent: :delete_all` relationships between models.

```ruby
class Author < ApplicationRecord
  has_many :books, dependent: :delete_all
end

class Book < ApplicationRecord
  has_many :chapters, dependent: :delete_all
end
```

--------------------------------

### ActiveRecordDoctor::Config Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/types.md

An example of how to instantiate and configure ActiveRecordDoctor::Config.

```ruby
config = ActiveRecordDoctor::Config.new(
  {
    ignore_tables: ["ar_internal_metadata", "schema_migrations"],
    ignore_models: ["TemporaryModel"]
  },
  {
    extraneous_indexes: {
      enabled: true,
      ignore_tables: [],
      ignore_indexes: []
    },
    missing_foreign_keys: {
      enabled: true,
      ignore_models: [],
      ignore_associations: []
    }
  }
)
```

--------------------------------

### Hierarchical Logger Detailed Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/logging.md

A more detailed example showcasing nested logging with the Hierarchical logger.

```ruby
logger = ActiveRecordDoctor::Logger::Hierarchical.new($stderr)

logger.log("extraneous_indexes") do
  logger.log("subindexes_of_multi_column_indexes") do
    logger.log("Iterating over data sources") do
      logger.log("users") do
        logger.log("Index idx_email_and_account") do
          logger.log("Problem found") do
            logger.log("table: users")
            logger.log("extraneous_index: idx_email_and_account")
          end
        end
      end
    end
  end
end
```

--------------------------------

### ConfigureNotCalled Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/errors.md

Example demonstrating ConfigureNotCalled when the configuration file does not call ActiveRecordDoctor.configure.

```ruby
# In .active_record_doctor.rb:
# (File is empty or has no call to configure)

config = ActiveRecordDoctor.load_config(".active_record_doctor.rb")
# => ActiveRecordDoctor::Error::ConfigureNotCalled
```

--------------------------------

### Integrate with Generator

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Output can be piped to the `add_indexes` generator.

```bash
bundle exec rake active_record_doctor:unindexed_foreign_keys > /tmp/missing_indexes.txt
rails generate active_record_doctor:add_indexes /tmp/missing_indexes.txt
```

```ruby
class IndexForeignKeysInPosts < ActiveRecord::Migration[7.0]
  def change
    add_index :posts, [:user_id]
  end
end
```

--------------------------------

### Generated Migration Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rails-integration.md

Example of a generated migration file.

```ruby
class IndexForeignKeysInUsers < ActiveRecord::Migration[7.0]
  def change
    add_index :users, [:account_id]
    add_index :users, [:organization_id]
  end
end
```

--------------------------------

### Complete Configuration Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/configuration.md

A comprehensive example of an .active_record_doctor.rb file, demonstrating global settings and configurations for various detectors.

```ruby
# .active_record_doctor.rb

ActiveRecordDoctor.configure do
  # Global settings - applied to multiple detectors
  global :ignore_tables, [
    "ar_internal_metadata",
    "schema_migrations",
    "active_storage_blobs",
    "active_storage_attachments",
    "action_text_rich_texts",
    "legacy_data",
    "archive_*"
  ]

  global :ignore_models, [
    "TemporaryModel",
    "LegacyUser"
  ]

  # Detection detectors - checks for missing constraints and validations
  detector :missing_foreign_keys,
    enabled: true,
    ignore_associations: ["User.organization"]

  detector :missing_presence_validation,
    enabled: true,
    ignore_attributes: ["User.bio"],
    ignore_columns_with_default: true

  detector :missing_non_null_constraint,
    enabled: true

  detector :missing_unique_indexes,
    enabled: true,
    ignore_columns: ["users.email"]

  # Index-related detectors
  detector :extraneous_indexes,
    enabled: true,
    ignore_indexes: ["idx_legacy_lookup"]

  detector :unindexed_foreign_keys,
    enabled: true

  detector :unindexed_deleted_at,
    enabled: true,
    column_names: ["deleted_at", "discarded_at"]

  # Validation detectors - checks for validation problems
  detector :incorrect_boolean_presence_validation,
    enabled: true

  detector :incorrect_length_validation,
    enabled: true

  detector :incorrect_dependent_option,
    enabled: true

  # Table structure detectors
  detector :short_primary_key_type,
    enabled: true

  detector :table_without_primary_key,
    enabled: true

  detector :table_without_timestamps,
    enabled: true,
    ignore_tables: ["lookup_tables"]

  detector :mismatched_foreign_key_type,
    enabled: true

  detector :undefined_table_references,
    enabled: true
end
```

--------------------------------

### Example usage of adapter detection methods in a detector

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/utilities.md

Example of using adapter detection methods within a detector class to implement adapter-specific logic.

```ruby
# Usage in detector code for adapter-specific logic
class MyDetector < ActiveRecordDoctor::Detectors::Base
  private
  
  def detect
    if Utils.postgresql?(connection)
      check_postgresql_specific
    elsif Utils.mysql?(connection)
      check_mysql_specific
    elsif Utils.sqlite?(connection)
      check_sqlite_specific
    end
  end
end
```

--------------------------------

### Missing Foreign Keys Configuration

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Configuration for the `missing_foreign_keys` detector.

```ruby
detector :missing_foreign_keys,
  enabled: true,
  ignore_models: ["LegacyModel"],
  ignore_associations: ["Post.author"]
```

--------------------------------

### Problem 1: Using delete instead of destroy with validations

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Example demonstrating a potential issue where `dependent: :delete_all` is used on an association with a model that has validations.

```ruby
class User < ApplicationRecord
  has_many :posts, dependent: :delete_all
end

class Post < ApplicationRecord
  validates :content, presence: true
end
```

--------------------------------

### Extraneous Indexes Detector Configuration Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/configuration.md

Example configuration for the `extraneous_indexes` detector.

```ruby
detector :extraneous_indexes,
  enabled: true,
  ignore_tables: ["users"],
  ignore_indexes: ["idx_custom_index"]
```

--------------------------------

### ActiveRecordDoctor Configuration Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rails-integration.md

Example configuration file for ActiveRecordDoctor, detailing various detectors and their settings.

```ruby
ActiveRecordDoctor.configure do
  # Global settings for all detectors
  global :ignore_tables, [
    # Rails internal tables
    "ar_internal_metadata",
    "schema_migrations",
    "active_storage_blobs",
    "active_storage_attachments",
    "action_text_rich_texts",
    
    # Project-specific exclusions
    "legacy_users",
    "archive_*",
    /^temp_/
  ]

  global :ignore_models, [
    "TemporaryModel",
    "LegacyUser"
  ]

  # Detection detectors
  detector :missing_foreign_keys,
    enabled: true,
    ignore_associations: [
      "Post.secondary_author",
      "Comment.soft_deleted_by"
    ]

  detector :missing_presence_validation,
    enabled: true,
    ignore_models: ["Post"],
    ignore_attributes: [
      "User.bio",
      "Account.notes"
    ],
    ignore_columns_with_default: true

  detector :missing_non_null_constraint,
    enabled: true,
    ignore_columns: ["users.bio"]

  detector :missing_unique_indexes,
    enabled: true,
    ignore_columns: ["users.email"],
    ignore_join_tables: ["user_roles"]

  # Index-related detectors
  detector :extraneous_indexes,
    enabled: true,
    ignore_tables: ["archive_items"],
    ignore_indexes: ["idx_legacy_lookup"]

  detector :unindexed_foreign_keys,
    enabled: true,
    ignore_columns: ["audit_logs.user_id"]

  detector :unindexed_deleted_at,
    enabled: true,
    column_names: ["deleted_at", "discarded_at", "archived_at"]

  # Validation detectors
  detector :incorrect_boolean_presence_validation,
    enabled: true

  detector :incorrect_length_validation,
    enabled: true

  detector :incorrect_dependent_option,
    enabled: true,
    ignore_associations: ["User.temporary_posts"]

  # Table structure detectors
  detector :short_primary_key_type,
    enabled: true,
    ignore_tables: ["lookup_tables"]

  detector :table_without_primary_key,
    enabled: true

  detector :table_without_timestamps,
    enabled: true,
    ignore_tables: ["junction_tables"]

  # Constraint and type detectors
  detector :mismatched_foreign_key_type,
    enabled: true

  detector :undefined_table_references,
    enabled: true
end
```

--------------------------------

### Missing Presence Validation Configuration

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Configuration for the missing_presence_validation detector.

```ruby
detector :missing_presence_validation,
  enabled: true,
  ignore_models: ["PostArchive"],
  ignore_attributes: ["User.bio"],
  ignore_columns_with_default: true
```

--------------------------------

### Missing Unique Indexes Configuration

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Configuration for the `missing_unique_indexes` detector.

```ruby
detector :missing_unique_indexes,
  enabled: true,
  ignore_models: ["TemporaryUser"],
  ignore_columns: ["users.email"],
  ignore_join_tables: ["user_roles"]
```

--------------------------------

### Example Schema for Missing Non-NULL Constraint

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

A schema definition showing a `users` table with an `email` column that allows NULL by default, which the detector might flag.

```ruby
create_table :users do |t|
  t.string :email  # Allows NULL by default!
end
```

--------------------------------

### Formatted Custom Logger Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/logging.md

An example of a more advanced custom logger that adds indentation and a prefix to log messages.

```ruby
class FormattedLogger
  def initialize(io, prefix: "[ARD]")
    @io = io
    @prefix = prefix
    @depth = 0
  end

  def log(message)
    @io.puts("#{@prefix}#{" " * @depth} #{message}")
    
    return unless block_given?
    
    @depth += 2
    result = yield
    @depth -= 2
    
    result
  end
end

logger = FormattedLogger.new($stderr)
runner = ActiveRecordDoctor::Runner.new(config: config, logger: logger)
```

--------------------------------

### Extraneous Indexes Configuration

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Configuration for the extraneous_indexes detector.

```ruby
detector :extraneous_indexes,
  enabled: true,
  ignore_tables: ["archive_items"],
  ignore_indexes: ["custom_idx_keep"]
```

--------------------------------

### Example: Displaying detector help

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/runner.md

Illustrates how to request and display help text for a detector, including its description and configuration options.

```ruby
runner.help(:missing_presence_validation)
# Output:
# missing_presence_validation - detect non-NULL columns without a corresponding presence validator
#
# Configuration options:
#   - enabled (local only) - set to false to disable the detector altogether
#   - ignore_models (local and global) - models whose underlying tables' columns should not be checked
#   - ignore_attributes (local only) - specific attributes, written as Model.attribute, that should not be checked
#   - ignore_columns_with_default (local only) - ignore columns with default values, should be provided as boolean
```

--------------------------------

### Unindexed Foreign Keys Configuration

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Configuration for the unindexed_foreign_keys detector.

```ruby
detector :unindexed_foreign_keys,
  enabled: true,
  ignore_tables: ["audit_logs"],
  ignore_columns: ["comments.user_id"]
```

--------------------------------

### Default Configuration Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/configuration.md

An example of the built-in default configuration used by ActiveRecord Doctor when no user configuration file is present.

```ruby
ActiveRecordDoctor.configure do
  global :ignore_tables, [
    "ar_internal_metadata",
    "schema_migrations",
    "active_storage_blobs",
    "active_storage_attachments",
    "action_text_rich_texts"
  ]

  # All detectors enabled with minimal settings
  detector :extraneous_indexes,
    enabled: true,
    ignore_tables: [],
    ignore_indexes: []

  # ... (all other detectors with defaults)
end
```

--------------------------------

### Incorrect Dependent Option Detector Configuration Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/configuration.md

Example configuration for the `incorrect_dependent_option` detector.

```ruby
detector :incorrect_dependent_option,
  enabled: true,
  ignore_models: [],
  ignore_associations: ["User.posts"]
```

--------------------------------

### Example Workflow - Step 1: Run detector and save output

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/generators.md

Demonstrates running the detector and saving output, showing the content of the output file.

```bash
$ bundle exec rake active_record_doctor:unindexed_foreign_keys > /tmp/indexes.txt
$ cat /tmp/indexes.txt

add an index on users(account_id) - consider adding an index on the foreign key
add an index on users(organization_id) - consider adding an index on the foreign key
add an index on posts(user_id) - consider adding an index on the foreign key
add an index on comments(post_id, user_id) - consider adding an index on the foreign key
```

--------------------------------

### ConfigurationError Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/errors.md

Example demonstrating a ConfigurationError due to an undefined variable in the configuration file.

```ruby
# In .active_record_doctor.rb:
ActiveRecordDoctor.configure do
  global :ignore_tables, undefined_variable  # NameError
end

# Running:
config = ActiveRecordDoctor.load_config(".active_record_doctor.rb")
# => ActiveRecordDoctor::Error::ConfigurationError
# Details will include: NameError (undefined local variable or method `undefined_variable')
```

--------------------------------

### Extraneous Indexes - Problem 1: Redundant single-column index

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Example of a redundant single-column index that can be dropped.

```ruby
create_table :users do |t|
  t.string :email, null: false
  t.integer :account_id, null: false
  t.index [:email, :account_id]  # Multi-column
  t.index :email                  # Extraneous! Can be dropped
end
```

--------------------------------

### Custom Configuration Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/README.md

Example of a custom configuration file (.active_record_doctor.rb) to ignore specific tables and configure a detector.

```ruby
ActiveRecordDoctor.configure do
  # Global settings affect all detectors.
  global :ignore_tables, [
    # Ignore internal Rails-related tables.
    "ar_internal_metadata",
    "schema_migrations",
    "active_storage_blobs",
    "active_storage_attachments",
    "action_text_rich_texts",

    # Add project-specific tables here.
    "legacy_users"
  ]

  # Detector-specific settings affect only one specific detector.
  detector :extraneous_indexes,
    ignore_tables: ["users"],
    ignore_indexes: ["accounts_on_email_organization_id"]
end
```

--------------------------------

### CheckConstraint Representation

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/types.md

Example of how to get check constraints for a table.

```ruby
constraints = connection.check_constraints("users")
```

--------------------------------

### Example Workflow - Step 2: Generate migrations

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/generators.md

Demonstrates generating migration files based on the prepared input file, showing the output.

```bash
$ rails generate active_record_doctor:add_indexes /tmp/indexes.txt

create  db/migrate/20240528120000_index_foreign_keys_in_users.rb
        class IndexForeignKeysInUsers < ActiveRecord::Migration[7.0]
          def change
            add_index :users, [:account_id]
            add_index :users, [:organization_id]
          end
        end

create  db/migrate/20240528120001_index_foreign_keys_in_posts.rb
        class IndexForeignKeysInPosts < ActiveRecord::Migration[7.0]
          def change
            add_index :posts, [:user_id]
          end
        end

create  db/migrate/20240528120002_index_foreign_keys_in_comments.rb
        class IndexForeignKeysInComments < ActiveRecord::Migration[7.0]
          def change
            add_index :comments, [:post_id, :user_id]
          end
        end
```

--------------------------------

### Extraneous Indexes - Problem 2: Index on primary key

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Example of an index on the primary key column, which is extraneous.

```ruby
create_table :users do |t|
  t.index :id  # Extraneous! Primary key already indexed
end
```

--------------------------------

### Dummy Logger log Method Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/logging.md

Execute a block without logging.

```ruby
logger.log("Processing") do
  # This code runs but nothing is logged
end
```

--------------------------------

### Index Representation

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/types.md

Example of how to get an index object from a connection.

```ruby
index = connection.indexes("users").first
```

--------------------------------

### Missing Presence Validation - Problem 1: Missing validator on NOT NULL column

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Example of a NOT NULL column without a presence validator.

```ruby
class User < ApplicationRecord
  # Column: email, type: string, null: false
  # No presence validator!
end
```

--------------------------------

### Incorrect Boolean Presence Validation Detector Configuration Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/configuration.md

Example configuration for the `incorrect_boolean_presence_validation` detector.

```ruby
detector :incorrect_boolean_presence_validation,
  enabled: true,
  ignore_models: ["User"],
  ignore_attributes: ["Post.published"]
```

--------------------------------

### ForeignKey Representation

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/types.md

Example of how to get a foreign key object from a connection.

```ruby
fk = connection.foreign_keys("posts").first
```

--------------------------------

### Example Usage of Ignore Patterns

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/types.md

An example of how to configure ignore patterns for tables in ActiveRecordDoctor.

```ruby
ActiveRecordDoctor.configure do
  global :ignore_tables, [
    "ar_internal_metadata",     # String exact match
    /^legacy_/,                 # Regexp match
    /^temp/i,                   # Case-insensitive regexp
    "archive_*"                 # Glob-like (treated as exact string)
  ]
end
```

--------------------------------

### Example Output for Short Primary Key Type

Source: https://github.com/gregnavis/active_record_doctor/blob/master/README.md

Example output indicating a primary key should be migrated to a wider integer type.

```text
change the type of companies.id to bigint
```

--------------------------------

### Example: Running a single detector

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/runner.md

Demonstrates how to set up the runner and execute a single detector, checking for missing foreign keys.

```ruby
config = ActiveRecordDoctor.load_config_with_defaults(nil)
logger = ActiveRecordDoctor::Logger::Dummy.new
runner = ActiveRecordDoctor::Runner.new(config: config, logger: logger)

success = runner.run_one(:missing_foreign_keys)
exit(1) unless success
```

--------------------------------

### Incorrect Boolean Presence Validation Configuration

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Configuration for the `incorrect_boolean_presence_validation` detector.

```ruby
detector :incorrect_boolean_presence_validation,
  enabled: true,
  ignore_models: ["LegacyModel"],
  ignore_attributes: ["Setting.enabled"]
```

--------------------------------

### Logger Interface Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/types.md

An example of a custom logger class implementing the required interface.

```ruby
class MyLogger
  def log(message)
    # ... logging implementation
    yield if block_given?  # Must yield to block if provided
  end
end
```

--------------------------------

### Detector Registry Example Usage

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/types.md

Example of retrieving all detectors and a specific detector class.

```ruby
all_detectors = ActiveRecordDoctor.detectors
# => {
#   :extraneous_indexes => ExtraneousIndexes class,
#   :missing_foreign_keys => MissingForeignKeys class,
#   ...
# }

detector_class = ActiveRecordDoctor.detectors[:extraneous_indexes]
# => ExtraneousIndexes class
```

--------------------------------

### Incorrect Dependent Option Configuration

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Configuration for the `incorrect_dependent_option` detector.

```ruby
detector :incorrect_dependent_option,
  enabled: true,
  ignore_models: ["Archive"],
  ignore_associations: ["Post.comments"]
```

--------------------------------

### Custom Configuration

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/INDEX.md

Example of creating a custom configuration file for ActiveRecordDoctor.

```ruby
ActiveRecordDoctor.configure do
  global :ignore_tables, ["legacy_data"]
  detector :extraneous_indexes, ignore_tables: ["users"]
end
```

--------------------------------

### Check Database Adapter

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/REFERENCE.md

Example of how to check the current database adapter type.

```ruby
if ActiveRecordDoctor::Utils.postgresql?
  # PostgreSQL-specific code
elsif ActiveRecordDoctor::Utils.mysql?
  # MySQL-specific code
elsif ActiveRecordDoctor::Utils.sqlite?
  # SQLite-specific code
end
```

--------------------------------

### Missing Presence Validation - Problem 2: Optional belongs_to with NOT NULL foreign key

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Example of an optional belongs_to association with a NOT NULL foreign key.

```ruby
class Post < ApplicationRecord
  belongs_to :user, optional: true  # But user_id is NOT NULL!
end
```

--------------------------------

### Build and Publish Gem

Source: https://github.com/gregnavis/active_record_doctor/blob/master/RELEASE_PROCESS.md

Commands to build and publish the gem to RubyGems.org.

```bash
gem build active_record_doctor.gemspec
gem push <GEM NAME>
```

--------------------------------

### Error message example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/generators.md

Example of an error message generated for malformed input.

```text
cannot extract table and column name from line 1: this line is malformed
```

--------------------------------

### Usage Example in Detector Code

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/utilities.md

Demonstrates how to use database adapter detection within a detector's `detect` method.

```ruby
module ActiveRecordDoctor
  module Detectors
    class MyDetector < Base
      private
      
      def detect
        # Check which database adapter is in use
        if Utils.postgresql?(connection)
          detect_postgresql_issues
        elsif Utils.mysql?(connection)
          detect_mysql_issues
        end
      end
      
      def detect_postgresql_issues
        # PostgreSQL-specific queries
      end
      
      def detect_mysql_issues
        # MySQL-specific queries
      end
    end
  end
end
```

--------------------------------

### locals_and_globals

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detectors-base.md

Get lists of local and global configuration settings for this detector.

```ruby
locals, globals = ActiveRecordDoctor::Detectors::ExtraneousIndexes.locals_and_globals
# => [[:enabled, :ignore_tables, :ignore_indexes], [:ignore_tables, :ignore_indexes]]
```

--------------------------------

### config(key)

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detectors-base.md

Get configuration value, automatically merging global and local settings.

```ruby
ignore_tables = config(:ignore_tables)
# Returns merged array of local + global ignore_tables
```

--------------------------------

### Custom Rails Setup

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rails-integration.md

For advanced configurations, create a custom Rake task in lib/tasks/.

```ruby
# lib/tasks/active_record_doctor.rb
require "active_record_doctor"

ActiveRecordDoctor::Rake::Task.new do |task|
  # Standard Rails setup
  task.deps = [:environment]
  
  # Custom setup after environment
  task.setup = lambda do
    Rails.application.eager_load!
    
    # Additional setup if needed
    require_relative "../../app/models/concerns/auditable"
  end
  
  # Custom config file location
  task.config_path = Rails.root.join("config/.active_record_doctor.rb")
end
```

--------------------------------

### ConfigurationError Constructor

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/errors.md

Example of creating a ConfigurationError instance.

```ruby
error = ActiveRecordDoctor::Error::ConfigurationError.new(original_exception)
```

--------------------------------

### Example Output Format for Help Text

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/utilities.md

Shows the expected output format for help text generated by ActiveRecordDoctor::Help.

```text
<detector_name> - <description>

Configuration options:
  - <setting_name> (<scope>) - <description>
  - <setting_name> (<scope>) - <description>
  ...

Where <scope> is either "local only" or "local and global"
```

--------------------------------

### Generate Migrations

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/INDEX.md

Example of generating migrations using ActiveRecordDoctor Rake tasks.

```bash
bundle exec rake active_record_doctor:unindexed_foreign_keys > /tmp/indexes.txt
rails generate active_record_doctor:add_indexes /tmp/indexes.txt
rails db:migrate
```

--------------------------------

### Find All Available Detectors

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/REFERENCE.md

How to get a list of all available detector keys.

```ruby
ActiveRecordDoctor.detectors.keys
# => [:extraneous_indexes, :missing_foreign_keys, ...]
```

--------------------------------

### Programmatic Usage

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/INDEX.md

Example of how to use ActiveRecordDoctor programmatically in Ruby.

```ruby
config = ActiveRecordDoctor.load_config_with_defaults(nil)
logger = ActiveRecordDoctor::Logger::Dummy.new
runner = ActiveRecordDoctor::Runner.new(config: config, logger: logger)
success = runner.run_all
```

--------------------------------

### Association Reflection Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/types.md

Example of reflecting on all associations of a model.

```ruby
User.reflect_on_all_associations.first
```

--------------------------------

### Hierarchical Logger log Method Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/logging.md

Log a message with indentation and execute a block with increased indentation.

```ruby
logger.log("Starting detection") do
  logger.log("Checking table: users") do
    # Nested logging
  end
  logger.log("Checking table: posts")
end
```

--------------------------------

### Get Current Version

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/REFERENCE.md

How to get the current version of the ActiveRecordDoctor gem.

```ruby
puts ActiveRecordDoctor::VERSION  # => "2.0.1"
```

--------------------------------

### Example Output for Incorrect `dependent` Option

Source: https://github.com/gregnavis/active_record_doctor/blob/master/README.md

Example outputs for incorrect `dependent` options on associations.

```text
use `dependent: :delete_all` or similar on Company.users - associated models have no validations and can be deleted in bulk
use `dependent: :destroy` or similar on Post.comments - the associated model has callbacks that are currently skipped
```

--------------------------------

### Rake Task - Production Mode

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/logging.md

Example of running the Rake task in production mode, resulting in no debug output.

```bash
# Production - no debug output
bundle exec rake active_record_doctor
```

--------------------------------

### Regexp-Based Ignores Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/README.md

Example of using regular expressions in the configuration to ignore tables and models.

```ruby
ActiveRecordDoctor.configure do
  global :ignore_tables, [
    # Ignore all legacy tables.
    /^legacy_/
  ]
  global :ignore_models, [
    # Ignore all legacy models.
    /^Legacy::/
  ]
end
```

--------------------------------

### Configuration for Missing Non-NULL Constraint Detector

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Configuration options for the `missing_non_null_constraint` detector, including enabling it and ignoring specific tables or columns.

```ruby
detector :missing_non_null_constraint,
  enabled: true,
  ignore_tables: ["archive_items"],
  ignore_columns: ["users.bio"]
```

--------------------------------

### Case-Insensitive Match for Ignore Settings

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/configuration.md

Example of using case-insensitive regular expressions for matching table names.

```ruby
ignore_tables: [/^system_/i]
# Matches system_logs, System_Data, SYSTEM_config, etc.
```

--------------------------------

### GitLab CI Integration

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rake-task.md

Example of integrating ActiveRecord Doctor into a GitLab CI pipeline.

```yaml
test-db:
  script:
    - bundle exec rake active_record_doctor
```

--------------------------------

### Incorrect Length Validation Detector Configuration Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/configuration.md

Example configuration for the `incorrect_length_validation` detector.

```ruby
detector :incorrect_length_validation,
  enabled: true,
  ignore_attributes: ["User.email"]
```

--------------------------------

### ActiveRecordDoctor::Help#to_s Method

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/utilities.md

Generates help text as a string.

```ruby
help = ActiveRecordDoctor::Help.new(ActiveRecordDoctor::Detectors::ExtraneousIndexes)
puts help.to_s
```

--------------------------------

### Column Introspection Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/types.md

Example of retrieving column information from the database.

```ruby
column = connection.columns("users").first
```

--------------------------------

### Detector Configuration Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detectors.md

Demonstrates how to configure detectors, including global and detector-specific settings like ignore lists and enabled flags.

```ruby
ActiveRecordDoctor.configure do
  # Global settings apply to all or multiple detectors
  global :ignore_tables, [
    "ar_internal_metadata",
    "schema_migrations",
    "active_storage_blobs",
    "active_storage_attachments",
    "action_text_rich_texts"
  ]

  # Detector-specific settings
  detector :extraneous_indexes,
    enabled: true,
    ignore_tables: ["users"],        # local override
    ignore_indexes: ["custom_idx"]   # local override

  detector :missing_presence_validation,
    enabled: true,
    ignore_models: ["Post"],
    ignore_attributes: ["User.bio"],
    ignore_columns_with_default: true
end
```

--------------------------------

### initialize(config:, logger:, io:)

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detectors-base.md

Create a new detector instance.

```ruby
detector = ActiveRecordDoctor::Detectors::ExtraneousIndexes.new(
  config: config,
  logger: logger,
  io: $stdout
)
```

--------------------------------

### Custom Rake Task Setup

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/utilities.md

Demonstrates how to define a custom Rake task using `ActiveRecordDoctor::Rake::Task` and how to integrate help text generation for detectors.

```ruby
ActiveRecordDoctor::Rake::Task.new do |task|
  task.deps = [:environment]
  
  # Help text generation in custom rake tasks
  task.setup = -> do
    Rails.application.eager_load!
    
    # Can use Help to show information
    help = ActiveRecordDoctor::Help.new(
      ActiveRecordDoctor::Detectors::ExtraneousIndexes
    )
    puts help if ENV["HELP"]
  end
end
```

--------------------------------

### Example Output for Incorrect Length Validations

Source: https://github.com/gregnavis/active_record_doctor/blob/master/README.md

Example outputs for length validation mismatches between model and database.

```text
set the maximum length in the validator of User.email (currently 32) and the database limit on users.email (currently 64) to the same value
add a length validator on User.address to enforce a maximum length of 64 defined on users.address
```

--------------------------------

### Run a Specific Detector Programmatically

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detector-examples.md

Ruby code to programmatically run a specific detector (`MissingPresenceValidation`) and output whether problems were found.

```ruby
config = ActiveRecordDoctor.load_config_with_defaults(nil)
logger = ActiveRecordDoctor::Logger::Hierarchical.new($stderr)
io = $stdout

success = ActiveRecordDoctor::Detectors::MissingPresenceValidation.run(
  config: config,
  logger: logger,
  io: io
)

puts success ? "No problems found" : "Problems were found"
```

--------------------------------

### Detector Configured Twice Error Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/errors.md

Example of a DetectorConfiguredTwice error when the same detector is configured more than once.

```ruby
raise ActiveRecordDoctor::Error::DetectorConfiguredTwice[:extraneous_indexes]
```

--------------------------------

### Debugging Output Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rails-integration.md

Example of the detailed output when debug logging is enabled for ActiveRecordDoctor.

```text
extraneous_indexes
  subindexes_of_multi_column_indexes
    Iterating over data sources
      users
        Index index_users_on_email_and_account_id
          ...
```

--------------------------------

### InclusionValidator Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/types.md

Example of defining an inclusion validation and retrieving the validator object.

```ruby
class User < ApplicationRecord
  validates :status, inclusion: { in: ["active", "inactive"] }
end

validator = User.validators.find { |v| v.is_a?(InclusionValidator) }
validator.attributes  # => [:status]
validator.options[:in]  # => ["active", "inactive"]
```

--------------------------------

### Step 4: Run Migrations

Source: https://github.com/gregnavis/active_record_doctor/blob/master/README.md

Command to apply the generated migrations to the database.

```bash
bundle exec rake db:migrate
```

--------------------------------

### PresenceValidator Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/types.md

Example of defining a presence validation and retrieving the validator object.

```ruby
class User < ApplicationRecord
  validates :email, presence: true
end

validator = User.validators.find { |v| v.is_a?(PresenceValidator) }
validator.attributes  # => [:email]
```

--------------------------------

### BelongsToReflection Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/types.md

Example of reflecting on a specific belongs_to association and accessing its methods.

```ruby
Post.reflect_on_association(:user)
reflection = Post.reflect_on_association(:user)
reflection.name             # => :user
reflection.macro            # => :belongs_to
reflection.foreign_key      # => "user_id"
reflection.optional?        # => false (if not explicitly set)
```

--------------------------------

### Using Dummy Logger with Runner (Production)

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/logging.md

Configuration and initialization of ActiveRecordDoctor with a Dummy logger for production environments.

```ruby
config = ActiveRecordDoctor.load_config_with_defaults(nil)
logger = ActiveRecordDoctor::Logger::Dummy.new
runner = ActiveRecordDoctor::Runner.new(config: config, logger: logger)

runner.run_all
# No debug output is produced
```

--------------------------------

### Display help text for a specific detector

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/runner.md

Shows detailed help information for a given detector.

```ruby
runner.help(:extraneous_indexes)
```

--------------------------------

### Duplicate Global Setting Error Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/errors.md

Example of a DuplicateGlobalSetting error when the same global setting is provided more than once.

```ruby
raise ActiveRecordDoctor::Error::DuplicateGlobalSetting[:ignore_tables]
```

--------------------------------

### Dummy Logger log Method with Return Value

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/logging.md

Example demonstrating the return value of the log method when a block is provided.

```ruby
logger = ActiveRecordDoctor::Logger::Dummy.new
result = logger.log("Processing users") do
  User.count
end
# Nothing is logged, but User.count is executed and result contains the count
```

--------------------------------

### Workflow - Step 3: Review generated migrations

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/generators.md

Commands to list and view the generated migration files.

```bash
ls db/migrate/*_index_*.rb
cat db/migrate/20240528120000_index_foreign_keys_in_users.rb
```

--------------------------------

### Default Configuration

Source: https://github.com/gregnavis/active_record_doctor/blob/master/README.md

Illustrates the default behavior where no configuration file is needed.

```bash
bundle exec active_record_doctor
```

--------------------------------

### GitLab CI/CD Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rails-integration.md

Example of integrating Active Record Doctor into a GitLab CI workflow.

```yaml
database_doctor:
  image: ruby:3.2
  services:
    - postgres:15
  variables:
    POSTGRES_DB: test
    POSTGRES_PASSWORD: postgres
  script:
    - bundle install
    - bundle exec rails db:setup
    - bundle exec rake active_record_doctor
```

--------------------------------

### Get database connection and column names

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detectors-base.md

Retrieves the database connection and then gets the names of all columns for a specified table.

```ruby
conn = connection
column_names = conn.columns("users").map(&:name)
```

--------------------------------

### Workflow - Step 4: Run migrations

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/generators.md

Command to apply the generated database migrations.

```bash
rails db:migrate
```

--------------------------------

### Unrecognized Global Setting Error Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/errors.md

Example of an UnrecognizedGlobalSetting error when an unknown global setting is used.

```ruby
raise ActiveRecordDoctor::Error::UnrecognizedGlobalSetting[
  :unknown_global,
  [:ignore_tables, :ignore_models, ...]
]
```

--------------------------------

### Migrate command

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/generators.md

Command to run database migrations.

```bash
$ bundle exec rails db:migrate
```

--------------------------------

### Unrecognized Detector Settings Error Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/errors.md

Example of an UnrecognizedDetectorSettings error when unknown settings are provided for a detector.

```ruby
raise ActiveRecordDoctor::Error::UnrecognizedDetectorSettings[
  :extraneous_indexes,
  [:unknown_setting],
  [:enabled, :ignore_tables, :ignore_indexes]
]
```

--------------------------------

### run

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/detectors-base.md

Execute the detector: call `detect`, format and output problems, and return success status.

```ruby
success = detector.run
```

--------------------------------

### GitHub Actions CI/CD Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rails-integration.md

Example of integrating Active Record Doctor into a GitHub Actions workflow.

```yaml
name: Database Checks

on:
  pull_request:
  push:
    branches: [main, develop]

jobs:
  database-doctor:
    runs-on: ubuntu-latest
    
    services:
      postgres:
        image: postgres:15
        env:
          POSTGRES_PASSWORD: postgres
        options: >-
          --health-cmd pg_isready
          --health-interval 10s
          --health-timeout 5s
          --health-retries 5
    
    steps:
      - uses: actions/checkout@v3
      
      - uses: ruby/setup-ruby@v1
        with:
          ruby-version: 3.2
          bundler-cache: true
      
      - name: Setup database
        run: bundle exec rails db:setup
      
      - name: Run Active Record Doctor
        run: bundle exec rake active_record_doctor
```

--------------------------------

### Basic Custom Logger Implementation

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/logging.md

Demonstrates the minimum requirements for a custom logger by implementing the `log` method.

```ruby
class MyLogger
  def log(message)
    puts "[#{Time.now}] #{message}"
    yield if block_given?
  end
end

logger = MyLogger.new
runner = ActiveRecordDoctor::Runner.new(config: config, logger: logger, io: $stdout)
```

--------------------------------

### ActiveRecordDoctor::Help Constructor

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/utilities.md

Constructor for the Help class.

```ruby
help = ActiveRecordDoctor::Help.new(detector_class)
```

--------------------------------

### Example Migration for Changing Primary Key Type

Source: https://github.com/gregnavis/active_record_doctor/blob/master/README.md

Example Ruby on Rails migration to change a primary key type to bigint.

```ruby
class ChangeCompaniesPrimaryKeyType < ActiveRecord::Migration[5.1]
  def change
    change_column :companies, :id, :bigint
  end
end
```

--------------------------------

### Run all available detectors

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/runner.md

Executes all detectors sequentially.

```ruby
runner.run_all
```

--------------------------------

### Example Output for Incorrect Boolean Presence Validation

Source: https://github.com/gregnavis/active_record_doctor/blob/master/README.md

Example output indicating a presence validator used incorrectly on a boolean column.

```text
replace the `presence` validator on User.active with `inclusion` - `presence` can't be used on booleans
```

--------------------------------

### Unrecognized Detector Name Error Example

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/errors.md

Example of how an UnrecognizedDetectorName error is raised when a configuration references a non-existent detector.

```ruby
raise ActiveRecordDoctor::Error::UnrecognizedDetectorName[
  :invalid_detector,
  [:extraneous_indexes, :missing_foreign_keys, ...]
]
```

--------------------------------

### Load Configuration

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/config.md

Load configuration from a Ruby file and return the Config object.

```ruby
config = ActiveRecordDoctor.load_config(".active_record_doctor.rb")
```

--------------------------------

### Automatic Logger Selection Examples

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/rake-task.md

Examples showing how to set the ACTIVE_RECORD_DOCTOR_DEBUG environment variable for different logging levels.

```bash
# Production - silent (Dummy logger)
bundle exec rake active_record_doctor

# Development - detailed output to stderr (Hierarchical logger)
ACTIVE_RECORD_DOCTOR_DEBUG=1 bundle exec rake active_record_doctor
```

--------------------------------

### Pattern 3: Get Help for a Detector

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/REFERENCE.md

Command to get help information for a specific detector, e.g., 'missing_presence_validation'.

```bash
bundle exec rake active_record_doctor:missing_presence_validation:help
```

--------------------------------

### Runner Constructor

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/runner.md

Initializes a new instance of the Runner class.

```ruby
ActiveRecordDoctor::Runner.new(config:, logger:, io: $stdout)
```

--------------------------------

### Access Current Configuration

Source: https://github.com/gregnavis/active_record_doctor/blob/master/_autodocs/api-reference/config.md

Demonstrates how to access the configuration object currently being processed by `load_config`.

```ruby
config = ActiveRecordDoctor.current_config
```