@ymmy/dbml-relationalizer

@ymmy/dbml-relationalizer is a CLI tool that generates DBML (Database Markup Language) representations of table relationships based on database schema information and relationship definition files.

Key Features:

• Automatically generate DBML by fetching schema information from an existing database
• Allow user-defined relationship additions through a relations.yml file
• Provide an inference feature that infers relationships from table and column names

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Installation

From npm (recommended)

npm install -g @ymmy/dbml-relationalizer

Or, clone the repository and install locally

git clone https://github.com/Ymmy833y/dbml-relationalizer.git
cd dbml-relationalizer
npm install
npm run build
npm link  # Global installation

After installation, you can use the relation2dbml command in your terminal or command line.

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Usage

Follow the steps below to generate DBML from a database schema and a custom relationship definition file:

1. Create a relations.yml file

Refer to relations.sample.yml for an example. For more details on how to write your own definitions, see Relationship Definition File.

2. Run the CLI command

For example:

relation2dbml mysql mysql://user:pass@localhost:3306/dbname -o schema.dbml

This connects to the specified MySQL database and processes the schema information along with any relationships defined in relations.yml.

3. Check the output

• If you specify an output file (e.g., -o schema.dbml), the resulting DBML is saved to that file.
• If you do not specify an output file, the DBML is printed to stdout (the console).

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Options

• -o, --out-file <pathspec>: Specify the output file path for the generated DBML. If omitted, the result is printed to stdout.
• -v, --verbose: Set log level to debug for more detailed logs.
• -i, --input-file <pathspec>: Specify the path to the relationship definition file (e.g., relations.yml). Defaults to ./relations.yml.

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Relationship Definition File (relations.yml)

If you want to define custom relationships, create a relations.yml file with the following structure:

inference:
  enabled: true
  strategy: default

relations:
  - parentQualifiedColumn: "users.id"
    childQualifiedColumns:
      - "orders.user_id"
    ignoreChildQualifiedColumns:
      - "some_other_table.user_id"
  - parentQualifiedColumn: "products.id"
    childQualifiedColumns:
      - "orders.product_id"
      
ignoreSelfReferences: false

Inference Feature

The inference feature looks at primary keys (PK) and unique keys to guess which tables and columns may be related, and generates inferred relationships in the DBML output. You can configure this in relations.yml under the inference section:

inference:
  enabled: true
  strategy: default  # 'default' (e.g., users.id), or 'identical' (e.g., users.user_id)

• enabled (boolean):
  Set to true to enable inference.

• strategy (string):

  • default: Uses pluralize to get the singular form of table names and looks for <singularTableName>_<primaryKey> columns (e.g., for users.id, look for user_id).
  • identical: Assumes child columns share the same name as the parent column (e.g., if the parent is users.user_id, the child is also %.user_id).

Defining Relationships Manually

Within the relations block, you can define relationships manually:

• parentQualifiedColumn (Required): Specifies the parent table’s column (wildcards not supported).
• childQualifiedColumns (Optional): Specifies the child table’s columns (% wildcard supported).
• ignoreChildQualifiedColumns (Optional): Specifies any child columns to exclude (% wildcard supported).

When entering values, please use the tableName.columnName format.

Wildcard Examples

• %.item_id: Matches any item_id column in all tables (e.g., foo.item_id)
• %.order_%date: Matches any column in all tables that starts with order_ and ends with date (e.g., foo.order_created_date, foo.order_date)

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About Self-Referencing Relationships

Although rare, self-referencing relationships are also supported.

• By default, ignoreSelfReferences is set to true, so self-referencing relationships are excluded without additional configuration.
• To include self-referencing relationships, set ignoreSelfReferences: false.

Example of Self-Referencing

When ignoreSelfReferences: false is specified, a self-referencing relationship such as the following may be generated:

Ref "infer_fk_user_user_user_id":"user"."user_id" < "user"."user_id"

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License

This tool is released under the MIT License. See the LICENSE file for details.