### Install acts_as_tenant Gem

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Add the acts_as_tenant gem to your application's Gemfile to include its multitenancy functionality.

```ruby
gem 'acts_as_tenant'
```

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

### ActsAsTenant Configuration Options

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Provides examples of configuring ActsAsTenant globally via an initializer, including setting `require_tenant` and customizing `job_scope`.

```ruby
ActsAsTenant.configure do |config| 
  config.require_tenant = false # true

  # Customize the query for loading the tenant in background jobs
  config.job_scope = ->{ all }
end
```

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

### Test Tenant Middleware Setup

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Configuration for RSpec integration tests to use `TestTenantMiddleware` for proper tenant isolation and cleanup between requests.

```ruby
# test.rb
require_dependency 'acts_as_tenant/test_tenant_middleware'

Rails.application.configure do
  config.middleware.use ActsAsTenant::TestTenantMiddleware
end
```

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

### Rails Console Tenant Setup

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Shows a configuration for Rails console to automatically set the current tenant to the first available account upon loading, and reset it after `reload!`.

```ruby
SET_TENANT_PROC = lambda do
  if defined?(Rails::Console)
    puts "> ActsAsTenant.current_tenant = Account.first"
    ActsAsTenant.current_tenant = Account.first
  end
end

Rails.application.configure do
  if Rails.env.development?
    # Set the tenant to the first account in development on load
    config.after_initialize do
      SET_TENANT_PROC.call
    end

    # Reset the tenant after calling 'reload!' in the console
    ActiveSupport::Reloader.to_complete do
      SET_TENANT_PROC.call
    end
  end
end
```

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

### Rails Migration and Model Setup for acts_as_tenant

Source: https://github.com/erwinm/acts_as_tenant/blob/master/docs/blog_post.md

This snippet demonstrates the necessary steps to integrate acts_as_tenant into a Rails application. It includes a database migration to add the tenant ID to a model and the model configuration using acts_as_tenant and validates_uniqueness_to_tenant.

```ruby
class Addaccounttoproject < ActiveRecord::Migration
  def change
    add_column :projects, :account_id, :integer
  end
end

class Project < ActiveRecord::Base
  acts_as_tenant(:account)
  validates_uniqueness_to_tenant :name
end
```

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

### Sidekiq Integration

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Instructions for integrating ActsAsTenant with Sidekiq by requiring a specific initializer file.

```ruby
require 'acts_as_tenant/sidekiq'
```

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

### Conditional require_tenant Configuration

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Demonstrates how to set `require_tenant` to a lambda for dynamic evaluation at runtime, allowing conditional tenant requirement based on request environment.

```ruby
ActsAsTenant.configure do |config|
  config.require_tenant = lambda do
    if $request_env.present?
      return false if $request_env["REQUEST_PATH"].start_with?("/admin/")
    end
  end
end
```

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

### Manually Set Current Tenant

Source: https://github.com/erwinm/acts_as_tenant/blob/master/docs/blog_post.md

Demonstrates how to manually set the current tenant within a controller. This involves fetching the tenant object first and then passing it to the `set_current_tenant_to` method.

```ruby
class ApplicationController < ActionController::Base
    current_account = Account.method_to_find_the_current_account
    set_current_tenant_to(current_account)
  end
```

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

### Manually Setting Current Tenant with before_action

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Demonstrates how to manually set the current tenant in a Rails application using a `before_action`. This involves declaring `set_current_tenant_through_filter` and defining a method to fetch and set the tenant.

```ruby
class ApplicationController < ActionController::Base
  set_current_tenant_through_filter
  before_action :your_method_that_finds_the_current_tenant

  def your_method_that_finds_the_current_tenant
    current_account = Account.find_it
    set_current_tenant(current_account)
  end
end
```

```ruby
class MembersController < ActionController::Base
  set_current_tenant_through_filter
  before_action :set_tenant
  before_action :set_member, only: [:show, :edit, :update, :destroy]

  def set_tenant
    set_current_tenant(current_user.account)
  end
end
```

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

### acts_as_tenant with belongs_to Options

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Demonstrates passing standard `belongs_to` options like `counter_cache` directly to the `acts_as_tenant` declaration.

```ruby
acts_as_tenant(:account, counter_cache: true)
```

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

### Custom Primary Key Configuration

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Shows how to specify a custom primary key for the `acts_as_tenant` association when it differs from the default `id`.

```ruby
acts_as_tenant(:account, :primary_key => 'primaryID')
```

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

### Custom Foreign Key Configuration

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Demonstrates how to specify a custom foreign key for the `acts_as_tenant` association when it differs from the default `account_id`.

```ruby
acts_as_tenant(:account, :foreign_key => 'accountID')
```

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

### Set Current Tenant by Subdomain or Domain

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Configure the ApplicationController to set the current tenant by first attempting to use the subdomain and then falling back to the domain if no subdomain match is found. It specifies the tenant model and the attributes for lookup.

```APIDOC
set_current_tenant_by_subdomain_or_domain(:account, :subdomain, :domain)

# Parameters:
#   :account: The model representing tenants (e.g., Account).
#   :subdomain: The attribute on the tenant model used for subdomain lookup (e.g., :subdomain).
#   :domain: The attribute on the tenant model used for domain lookup (e.g., :domain).
#
# Options:
#   subdomain_lookup: :first or :last (default) to specify which subdomain to use if multiple exist.
#
# Example:
# class ApplicationController < ActionController::Base
#   set_current_tenant_by_subdomain_or_domain(:account, :subdomain, :domain)
# end
```

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

### HABTM Association Scoping

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Illustrates how to scope a model in a `has_and_belongs_to_many` relationship using the `through` option with `acts_as_tenant`.

```ruby
class Organisation < ActiveRecord::Base
  has_many :organisations_users
  has_many :users, through: :organisations_users
end

class User < ActiveRecord::Base
  has_many :organisations_users
  acts_as_tenant :organisation, through: :organisations_users
end

class OrganisationsUser < ActiveRecord::Base
  belongs_to :user
  acts_as_tenant :organisation
end
```

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

### Rails Default Error Page Styling

Source: https://github.com/erwinm/acts_as_tenant/blob/master/spec/dummy/public/422.html

This snippet contains CSS styles for a default Rails error page, typically displayed for unhandled exceptions or specific HTTP error codes like 422 (Unprocessable Entity). It defines the layout and appearance of error messages.

```css
.rails-default-error-page { background-color: #EFEFEF; color: #2E2F30; text-align: center; font-family: arial, sans-serif; margin: 0; }
.rails-default-error-page div.dialog { width: 95%; max-width: 33em; margin: 4em auto 0; }
.rails-default-error-page div.dialog > div { border: 1px solid #CCC; border-right-color: #999; border-left-color: #999; border-bottom-color: #BBB; border-top: #B00100 solid 4px; border-top-left-radius: 9px; border-top-right-radius: 9px; background-color: white; padding: 7px 12% 0; box-shadow: 0 3px 8px rgba(50, 50, 50, 0.17); }
.rails-default-error-page h1 { font-size: 100%; color: #730E15; line-height: 1.5em; }
.rails-default-error-page div.dialog > p { margin: 0 0 1em; padding: 1em; background-color: #F7F7F7; border: 1px solid #CCC; border-right-color: #999; border-left-color: #999; border-bottom-color: #999; border-bottom-left-radius: 4px; border-bottom-right-radius: 4px; border-top-color: #DADADA; color: #666; box-shadow: 0 3px 8px rgba(50, 50, 50, 0.17); }
```

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

### RSpec Configuration for ActsAsTenant

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Configures RSpec to manage tenant switching for tests. It sets a default account before the suite runs and manages the `current_tenant` and `test_tenant` based on test type (request or other). It also clears the tenant after each test.

```ruby
config.before(:suite) do |example|
  # Make the default tenant globally available to the tests
  $default_account = Account.create!
end

config.before(:each) do |example|
  if example.metadata[:type] == :request
    # Set the `test_tenant` value for integration tests
    ActsAsTenant.test_tenant = $default_account
  else
    # Otherwise just use current_tenant
    ActsAsTenant.current_tenant = $default_account
  end
end

config.after(:each) do |example|
  # Clear any tenancy that might have been set
  ActsAsTenant.current_tenant = nil
  ActsAsTenant.test_tenant = nil
end
```

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

### Set Current Tenant by Subdomain

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Configure the ApplicationController to automatically set the current tenant based on the subdomain of the incoming request. It specifies the tenant model and the attribute used for lookup.

```APIDOC
set_current_tenant_by_subdomain(:account, :subdomain)

# Parameters:
#   :account: The model representing tenants (e.g., Account).
#   :subdomain: The attribute on the tenant model used for subdomain lookup (e.g., :subdomain).
#
# Options:
#   subdomain_lookup: :first or :last (default) to specify which subdomain to use if multiple exist.
#
# Example:
# class ApplicationController < ActionController::Base
#   set_current_tenant_by_subdomain(:account, :subdomain)
# end
```

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

### Set Current Tenant by Subdomain

Source: https://github.com/erwinm/acts_as_tenant/blob/master/docs/blog_post.md

Configures acts_as_tenant to determine the current tenant based on the request's subdomain. It specifies the tenant model (e.g., Account) and the attribute on that model that stores the subdomain.

```ruby
class ApplicationController < ActionController::Base
    set_current_tenant_by_subdomain(:account, :subdomain)
  end
```

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

### Scoping Models with acts_as_tenant

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Details how to configure a Rails model to be tenant-scoped using `acts_as_tenant`. This requires a corresponding tenant ID column in the model's database table. When a current tenant is set, all queries and new object creations for this model will be automatically scoped.

```ruby
class AddAccountToProjects < ActiveRecord::Migration
  def up
    add_column :projects, :account_id, :integer
    add_index  :projects, :account_id
  end
end
```

```ruby
class Project < ActiveRecord::Base
  acts_as_tenant(:account)
end
```

```ruby
# Manually setting the current tenant for testing
ActsAsTenant.current_tenant = Account.find(3)

# All searches are scoped by the tenant
Project.all # => all projects with account_id == 3
Project.tasks.all # => all tasks with account_id == 3

# New objects are scoped to the current tenant
@project = Project.new(:name => 'big project') # => <#Project id: nil, name: 'big project', :account_id: 3>

# It will not allow the creation of objects outside the current_tenant scope
@project.account_id = 2
@project.save # => false

# It will not allow association with objects outside the current tenant scope
@task = Task.new # => <#Task id: nil, name: nil, project_id: nil, :account_id: 3>

```

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

### Unprocessable Entity Error Message

Source: https://github.com/erwinm/acts_as_tenant/blob/master/spec/dummy/public/422.html

This snippet represents a typical error message displayed in a Rails application when a request is rejected due to being unprocessable, often indicated by a 422 HTTP status code. It suggests potential causes and advises checking logs.

```text
The change you wanted was rejected (422)  .

The change you wanted was rejected.
===================================

Maybe you tried to change something you didn't have access to.

If you are the application owner check the logs for more information.
```

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

### Setting Tenant for a Block of Code

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Shows how to set the current tenant for a specific block of code using `ActsAsTenant.with_tenant`. This is useful for background jobs or isolated operations that need to run within a particular tenant's context. All tenant-setting methods are thread-safe.

```ruby
ActsAsTenant.with_tenant(current_account) do
  # Current tenant is set for all code in this block
end
```

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

### Allowing Tenant Updating for a Block

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Illustrates how to enable tenant updating for models within a specific block of code using `ActsAsTenant.with_mutable_tenant`. This feature is useful for administrative screens where users might need to change the tenant associated with existing models.

```ruby
ActsAsTenant.with_mutable_tenant do
  # Tenant updating is enabled for all code in this block
end
```

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

### Redundant belongs_to Declaration

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Highlights that `belongs_to :account` is redundant when `acts_as_tenant(:account)` is already declared on the model.

```ruby
class User < ActiveRecord::Base
  acts_as_tenant(:account) # YES
  belongs_to :account # REDUNDANT
end
```

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

### Uniqueness Validation within Tenant Scope

Source: https://github.com/erwinm/acts_as_tenant/blob/master/docs/blog_post.md

Explains the use of `validates_uniqueness_to_tenant` for enforcing unique attribute values within the scope of the current tenant. This method accepts the same options as the standard `validates_uniqueness_of` validator.

```ruby
validates_uniqueness_to_tenant :attribute_name
```

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

### Validating Uniqueness within Tenant Scope

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Explains how to enforce unique attribute validation scoped to the current tenant using `validates_uniqueness_to_tenant`. This method accepts all the same options as Rails' `validates_uniqueness_of`.

```ruby
validates_uniqueness_to_tenant :name, :email
```

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

### Disabling Tenant Checking for a Block

Source: https://github.com/erwinm/acts_as_tenant/blob/master/README.md

Explains how to temporarily disable tenant checking for a block of code using `ActsAsTenant.without_tenant`. This is beneficial for shared routes or administrative interfaces where tenant scoping might not be desired or required.

```ruby
ActsAsTenant.without_tenant do
  # Tenant checking is disabled for all code in this block
end
```

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