### Mermerd Example Usages

Source: https://github.com/karnerth/mermerd/blob/master/readme.md

Demonstrates various ways to invoke Mermerd, from interactive CLI usage to specifying configurations via flags and run files.

```bash
# all parameters are provided via the interactive cli
mermerd
```

```bash
# same as previous one, but show all constraints even though the table of the resulting constraint was not selected
mermerd --showAllConstraints
```

```bash
# ERD is created via the provided run config
mermerd --runConfig yourRunConfig.yaml
```

```bash
# specify all connection properties so that only the table selection is done via the interactive cli
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public
```

```bash
# same as previous one, but use all available tables without interaction
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public --useAllTables
```

```bash
# same as previous one, but get the result in stdout instead of a file
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public --useAllTables --outputMode stdout
```

```bash
# same as previous one, but use a list of tables without interaction
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public --selectedTables article,article_label
```

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

### Install Mermerd using Go Toolchain

Source: https://context7.com/karnerth/mermerd/llms.txt

Install the latest or a specific version of Mermerd using the Go toolchain. Verify the installation by checking the version.

```sh
go install github.com/KarnerTh/mermerd@latest
```

```sh
go install github.com/KarnerTh/mermerd@v0.13.0
```

```sh
mermerd version
# Output: mermerd v0.13.0 <commit-hash>
```

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

### Mermerd Global Configuration File Example

Source: https://github.com/karnerth/mermerd/blob/master/readme.md

Configure default Mermerd settings using a `.mermerd` YAML file in your home directory. This file can set persistent options and provide connection string suggestions.

```yaml
showAllConstraints: true
encloseWithMermaidBackticks: true
outputFileName: "my-db.mmd"
debug: false
omitConstraintLabels: false
omitAttributeKeys: false
showDescriptions: "enumValues"
showSchemaPrefix: true
schemaPrefixSeparator: "_"

# These connection strings are available as suggestions in the cli (use tab to access)
connectionStringSuggestions:
  - postgresql://user:password@localhost:5432/yourDb
  - mysql://root:password@tcp(127.0.0.1:3306)/yourDb
  - sqlserver://user:password@localhost:1433?database=yourDb
  - sqlite3://mermerd_test.db
```

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

### Install Mermerd using Go Toolchain

Source: https://github.com/karnerth/mermerd/blob/master/readme.md

Install the latest or a specific version of Mermerd using the go install command. Requires go version >= 1.21.

```sh
go install github.com/KarnerTh/mermerd@latest
```

```sh
go install github.com/KarnerTh/mermerd@v0.12.0
```

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

### Mermerd Run Configuration File Example

Source: https://github.com/karnerth/mermerd/blob/master/readme.md

Define all necessary parameters for generating an ERD in a YAML file, which can then be used with the `--runConfig` flag. This is useful for CI/CD pipelines.

```yaml
# Connection properties
connectionString: "postgresql://user:password@localhost:5432/yourDb"

# Define what schemas should be used
useAllSchemas: true
# or
schema: 
  - "public"
  - "other_db"

# Define what tables should be used
useAllTables: true
# or
selectedTables:
  - city
  - customer

# Additional flags
showAllConstraints: true
encloseWithMermaidBackticks: true
outputFileName: "my-db.mmd"
outputMode: stdout
debug: true
omitConstraintLabels: true
omitAttributeKeys: true
showDescriptions:
  - enumValues
  - columnComments
  - notNull
showSchemaPrefix: true
schemaPrefixSeparator: "_"
ignoreTables:
  - city

# Names must match the pattern <schema><schema_prefix><table>
relationshipLabels:
  - "public_table public_another-table : label"
```

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

### Example Mermaid ER Diagram Output

Source: https://context7.com/karnerth/mermerd/llms.txt

A complete ER diagram generated by Mermerd, showcasing schema prefixes, description options, and relationship symbols.

```mermaid
erDiagram
    public_article {
        int4 id PK "{NOT_NULL}"
        varchar status FK "<active,inactive> {NOT_NULL}"
        varchar title "{NOT_NULL}"
        int4 author_id FK
    }
    public_author {
        int4 id PK "{NOT_NULL}"
        varchar name "{NOT_NULL}"
    }

    public_article }o--|| public_author : "author_id"
```

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

### Run Unit Tests

Source: https://github.com/karnerth/mermerd/blob/master/readme.md

Execute unit tests using the `go test` command with the `--short` flag. This command runs all unit tests and provides verbose output.

```bash
go test --short -v ./...
```

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

### Run All Tests

Source: https://github.com/karnerth/mermerd/blob/master/readme.md

Execute all unit and integration tests using the `go test` command. This command runs all tests and provides verbose output.

```bash
go test -v ./...
```

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

### Run Unit Tests with Makefile

Source: https://github.com/karnerth/mermerd/blob/master/readme.md

Use the `make test-unit` target to run all unit tests.

```bash
make test-unit
```

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

### Run All Tests with Makefile

Source: https://github.com/karnerth/mermerd/blob/master/readme.md

Use the `make test-all` target to run all unit and integration tests.

```bash
make test-all
```

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

### Run Mermerd in Interactive CLI Mode

Source: https://context7.com/karnerth/mermerd/llms.txt

Launch Mermerd interactively to be prompted for connection string, schema, and table selection. Use `--showAllConstraints` to include constraints for tables not explicitly selected.

```sh
# Fully interactive: prompts for connection string, schema, and tables
mermerd
```

```sh
# Show all constraints even for tables not in the selection
mermerd --showAllConstraints
```

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

### Create Database Connector with Factory

Source: https://context7.com/karnerth/mermerd/llms.txt

Use the ConnectorFactory to create a database connector based on the connection string prefix. Supported prefixes include postgresql, mysql, sqlserver, and sqlite3. Ensure proper error handling for unrecognized prefixes.

```go
package main

import (
    "fmt"
    "github.com/KarnerTh/mermerd/database"
)

func main() {
    factory := database.NewConnectorFactory()

    // Create a PostgreSQL connector
    connector, err := factory.NewConnector("postgresql://user:password@localhost:5432/mydb")
    if err != nil {
        panic(err) // "could not create connector for db" if prefix is unrecognized
    }

    // Connect to the database
    if err := connector.Connect(); err != nil {
        panic(err)
    }
    defer connector.Close()

    // Retrieve available schemas
    schemas, err := connector.GetSchemas()
    if err != nil {
        panic(err)
    }
    fmt.Println("Schemas:", schemas) // e.g. [public audit]

    // Retrieve tables for a schema
    tables, err := connector.GetTables([]string{"public"})
    if err != nil {
        panic(err)
    }
    // tables: []TableDetail{{Schema:"public", Name:"article"}, {Schema:"public", Name:"author"}, ...}

    // Retrieve columns for a specific table
    columns, err := connector.GetColumns(database.TableDetail{Schema: "public", Name: "article"})
    if err != nil {
        panic(err)
    }
    for _, col := range columns {
        fmt.Printf("  %s %s PK=%v FK=%v Unique=%v Nullable=%v\n",
            col.DataType, col.Name, col.IsPrimary, col.IsForeign, col.IsUnique, col.IsNullable)
    }

    // Retrieve FK/PK constraints for a table
    constraints, err := connector.GetConstraints(database.TableDetail{Schema: "public", Name: "article"})
    if err != nil {
        panic(err)
    }
    for _, c := range constraints {
        fmt.Printf("  FK %s.%s → PK %s.%s (col: %s)\n",
            c.FkSchema, c.FkTable, c.PkSchema, c.PkTable, c.ColumnName)
    }
}
```

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

### Control Output Destination and Format

Source: https://context7.com/karnerth/mermerd/llms.txt

Configure the output using `--outputMode` and `-o` / `--outputFileName`. Default is `result.mmd`. Use `stdout` for piping and `-e` to enclose output in Mermaid fences for Markdown embedding.

```sh
# Write to a specific file
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public \
  --useAllTables -o schema-diagram.mmd
```

```sh
# Stream to stdout (e.g. for piping into another tool)
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public \
  --useAllTables --outputMode stdout
```

```sh
# Enclose output in mermaid backtick fences for GitHub Markdown embedding
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public \
  --useAllTables --outputMode stdout -e
# Output:
# ```mermaid
# erDiagram
#     article { ... }
# ```
```

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

### Run Mermerd with a Configuration File

Source: https://context7.com/karnerth/mermerd/llms.txt

Use `--runConfig` to specify a YAML file containing all Mermerd flags for non-interactive diagram generation, suitable for CI/CD.

```yaml
# ci-erd.yaml — full run configuration example

# Database connection
connectionString: "postgresql://user:password@localhost:5432/yourDb"

# Schema selection (pick one approach)
useAllSchemas: false
schema:
  - "public"
  - "audit"

# Table selection (pick one approach)
useAllTables: false
selectedTables:
  - public.article
  - public.author
  - public.label
  - audit.change_log

# Tables to ignore (supports regex patterns)
ignoreTables:
  - schema_migrations
  - "temp_.*"

# Output settings
outputFileName: "docs/schema.mmd"
outputMode: file          # or: stdout
encloseWithMermaidBackticks: true

# Diagram display options
showAllConstraints: true
omitConstraintLabels: false
omitAttributeKeys: false
showDescriptions:
  - enumValues
  - columnComments
  - notNull
showSchemaPrefix: true
schemaPrefixSeparator: "_"

# Custom relationship labels (format: "<fkTable> <pkTable> : <label>")
relationshipLabels:
  - "public_article public_author : written_by"
  - "public_article public_label : tagged_with"

debug: false

```

```sh
# Run mermerd using the config file
mermerd --runConfig ci-erd.yaml

# Environment variables are expanded inside the config file
# e.g. connectionString: "$DATABASE_URL"
DATABASE_URL="postgresql://user:secret@prod-db:5432/app" mermerd --runConfig ci-erd.yaml
```

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

### Provide Database Connection String via CLI

Source: https://context7.com/karnerth/mermerd/llms.txt

Specify the database connection string directly using the `-c` or `--connectionString` flag. The tool auto-detects the database type. Ensure passwords with special characters are percent-encoded.

```sh
# PostgreSQL
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public
```

```sh
# MySQL
mermerd -c "mysql://root:password@tcp(127.0.0.1:3306)/yourDb" -s myschema
```

```sh
# MSSQL / SQL Server
mermerd -c "sqlserver://user:password@localhost:1433?database=yourDb" -s dbo
```

```sh
# SQLite3
mermerd -c "sqlite3://path/to/yourDb.db"
```

```sh
# Passwords with special characters must be percent-encoded
# e.g. password$ → password%24
mermerd -c "postgresql://user:password%24@localhost:5432/yourDb" -s public
```

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

### Generate ER Diagram with Descriptions

Source: https://github.com/karnerth/mermerd/blob/master/readme.md

Use this command to generate an ER diagram including enum values, column comments, and notNull constraints from a PostgreSQL database.

```bash
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public --useAllTables --showDescriptions enumValues,columnComments,notNull
```

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

### Prefix Table Names with Schema

Source: https://context7.com/karnerth/mermerd/llms.txt

Use `--showSchemaPrefix` to prefix table names with their schema. Use `--schemaPrefixSeparator` to change the default '.' separator.

```sh
mermerd -c "postgresql://user:password@localhost:5432/yourDb" \
  --useAllSchemas --useAllTables --showSchemaPrefix
```

```sh
mermerd -c "postgresql://user:password@localhost:5432/yourDb" \
  --useAllSchemas --useAllTables --showSchemaPrefix --schemaPrefixSeparator "_"
```

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

### Global Configuration File Defaults

Source: https://context7.com/karnerth/mermerd/llms.txt

A global YAML file (`~/.mermerd`) sets persistent defaults for all Mermerd runs and provides connection string suggestions for the interactive CLI.

```yaml
# ~/.mermerd

showAllConstraints: true
encloseWithMermaidBackticks: false
outputFileName: "my-db.mmd"
debug: false
omitConstraintLabels: false
omitAttributeKeys: false
showDescriptions: "enumValues"
showSchemaPrefix: true
schemaPrefixSeparator: "_"

# Suggested connection strings shown in interactive CLI (press Tab to cycle)
connectionStringSuggestions:
  - postgresql://user:password@localhost:5432/yourDb
  - mysql://root:password@tcp(127.0.0.1:3306)/yourDb
  - sqlserver://user:password@localhost:1433?database=yourDb
  - sqlite3://mermerd_test.db

```

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

### Configure Table Selection via CLI Flags

Source: https://context7.com/karnerth/mermerd/llms.txt

Bypass interactive table selection using `--useAllTables` to include all tables or `--selectedTables` to specify a comma-separated list. Use `--ignoreTables` to exclude tables matching a pattern.

```sh
# Use every table in the schema — no prompts at all
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public --useAllTables
```

```sh
# Select specific tables (comma-separated)
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public \
  --selectedTables article,article_label,author
```

```sh
# Ignore tables matching a name or regex pattern
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public \
  --useAllTables --ignoreTables migrations,schema_version,"temp_.*"
```

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

### Orchestrate Database Analysis with Analyzer

Source: https://context7.com/karnerth/mermerd/llms.txt

The Analyzer orchestrates the database schema analysis workflow, including connection, schema/table selection, and data collection. It requires configuration, a connector factory, and an interactive questioner. The result is a `*database.Result` object.

```go
package main

import (
    "fmt"
    "github.com/KarnerTh/mermerd/analyzer"
    "github.com/KarnerTh/mermerd/config"
    "github.com/KarnerTh/mermerd/database"
)

func main() {
    // NewConfig reads from ~/.mermerd or the --runConfig file via viper
    conf := config.NewConfig()
    factory := database.NewConnectorFactory()
    questioner := analyzer.NewQuestioner() // handles interactive CLI prompts

    a := analyzer.NewAnalyzer(conf, factory, questioner)

    result, err := a.Analyze()
    if err != nil {
        panic(err)
    }

    // result.Tables is []database.TableResult, sorted deterministically
    for _, t := range result.Tables {
        fmt.Printf("Table: %s.%s (%d columns, %d constraints)\n",
            t.Table.Schema, t.Table.Name, len(t.Columns), len(t.Constraints))
    }
}
```

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

### Include External Foreign-Key Constraints

Source: https://context7.com/karnerth/mermerd/llms.txt

The `--showAllConstraints` flag includes foreign-key constraints that reference tables outside the selected set. Referenced tables appear as stubs with only their names.

```sh
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public \
  --selectedTables order --showAllConstraints
# Diagram will show the `order` table fully and also render stub nodes for
```

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

### Render Database Schema to Mermaid ERD

Source: https://context7.com/karnerth/mermerd/llms.txt

The Diagram Renderer converts a `*database.Result` into Mermaid ERD syntax. It can write the output to any `io.Writer`, such as `os.Stdout` or a `strings.Builder` for further processing. The renderer uses an embedded Go template.

```go
package main

import (
    "os"
    "strings"

    "github.com/KarnerTh/mermerd/config"
    "github.com/KarnerTh/mermerd/database"
    "github.com/KarnerTh/mermerd/diagram"
)

func main() {
    conf := config.NewConfig()
    d := diagram.NewDiagram(conf)

    // Build a result manually (normally comes from analyzer.Analyze())
    result := &database.Result{
        Tables: []database.TableResult{
            {
                Table: database.TableDetail{Schema: "public", Name: "article"},
                Columns: []database.ColumnResult{
                    {Name: "id", DataType: "int4", IsPrimary: true},
                    {Name: "title", DataType: "varchar", IsNullable: false},
                    {Name: "author_id", DataType: "int4", IsForeign: true},
                },
                Constraints: database.ConstraintResultList{
                    {FkTable: "article", FkSchema: "public", PkTable: "author", PkSchema: "public",
                        ColumnName: "author_id", IsPrimary: false, HasMultiplePK: false},
                },
            },
        },
    }

    // Write diagram to stdout
    if err := d.Create(os.Stdout, result); err != nil {
        panic(err)
    }
    // Output:
    // erDiagram
    //     article {
    //         int4 id PK
    //         int4 author_id FK
    //         varchar title
    //     }
    // 
    //     article }o--|| author : "author_id"

    // Or write to a buffer for further processing
    var buf strings.Builder
    _ = d.Create(&buf, result)
    mermaidSyntax := buf.String()
    _ = mermaidSyntax
}
```

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

### Annotate ERD Columns with Descriptions

Source: https://context7.com/karnerth/mermerd/llms.txt

Use `--showDescriptions` with a comma-separated list of `notNull`, `enumValues`, and `columnComments` to add annotations to columns in the ERD. This helps in documenting column properties.

```sh
# Show all description annotations
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public \
  --useAllTables --showDescriptions enumValues,columnComments,notNull
```

```sh
# Show only enum values and NOT NULL markers
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public \
  --useAllTables --showDescriptions enumValues,notNull
```

```sh
# Example output column line with annotations:
#   varchar status FK "active,inactive {NOT_NULL}"
```

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

### Mermerd Testing Commands

Source: https://context7.com/karnerth/mermerd/llms.txt

Commands for running Mermerd's unit and integration tests. Integration tests require Docker to be running.

```sh
# Unit tests only (no database needed)
go test --short -v ./...
# or
make test-unit
```

```sh
# All tests (unit + integration) — requires Docker containers running
cd test && docker-compose up -d && cd ..
go test -v ./...
# or
make test-all
```

```sh
# Generate mocks (requires mockery)
make create-mocks
# or
mockery --all
```

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

### Mermerd Command-Line Flags

Source: https://github.com/karnerth/mermerd/blob/master/readme.md

View available command-line flags and their descriptions using `mermerd -h`. These flags allow for direct configuration of Mermerd's behavior.

```bash
  -c, --connectionString string       connection string that should be used
      --debug                         show debug logs        
  -e, --encloseWithMermaidBackticks   enclose output with mermaid backticks (needed for e.g. in markdown viewer)
  -h, --help                          help for mermerd
      --ignoreTables strings          ignore the given tables (supports regex)
      --omitAttributeKeys             omit the attribute keys (PK, FK, UK)
      --omitConstraintLabels          omit the constraint labels
  -o, --outputFileName string         output file name (default "result.mmd")
      --outputMode OutputModeType     output mode (file, stdout) (default file)
      --runConfig string              run configuration (replaces global configuration)
  -s, --schema string                 schema that should be used
      --schemaPrefixSeparator string  the separator that should be used between schema and table name (default ".")
      --selectedTables strings        tables to include
      --showAllConstraints            show all constraints, even though the table of the resulting constraint was not selected
      --showDescriptions strings      show 'notNull', enumValues' and/or 'columnComments' in the description column
      --showSchemaPrefix              show schema prefix in table name
      --useAllSchemas                 use all available schemas
      --useAllTables                  use all available tables
      --relationshipLabels strings    use a different label besides the column name for specific table relationships; overrides `omitConstraintLabels` if specified
```

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

### Omit Constraint Labels and Attribute Keys

Source: https://context7.com/karnerth/mermerd/llms.txt

Use `--omitConstraintLabels` and `--omitAttributeKeys` to reduce diagram verbosity by hiding FK labels and PK/FK/UK badges.

```sh
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public \
  --useAllTables --omitConstraintLabels --omitAttributeKeys
```

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

### Override Relationship Labels

Source: https://context7.com/karnerth/mermerd/llms.txt

Use `--relationshipLabels` to set custom labels for FK relationships. Format: `<fkTable> <pkTable> : <label>`.

```sh
mermerd -c "postgresql://user:password@localhost:5432/yourDb" -s public \
  --useAllTables \
  --relationshipLabels "article author : written_by" \
                       "article label : tagged_with"
```

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

### Mermerd ERD Cardinality Symbols

Source: https://context7.com/karnerth/mermerd/llms.txt

Illustrates the Mermaid symbols used by Mermerd for one-to-one and many-to-one relationships based on foreign key constraints.

```text
article |o--|| author : "author_id"   ← article.author_id is its only PK
article_label }o--|| article : "article_id" ← composite PK or non-PK FK
```

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

### Percent Encoding Special Characters in Passwords

Source: https://github.com/karnerth/mermerd/blob/master/readme.md

When passwords contain special characters, they may cause URL parsing errors. Use percent encoding to work around this issue.

```bash
postgresql://user:password%24@localhost:5432/yourDb
```

```bash
postgresql://user:pass%5B%5D%3B%24%2Fword@localhost:5432/yourDb
```

=== COMPLETE CONTENT === This response contains all available snippets from this library. No additional content exists. Do not make further requests.