Plugins

Plugins in Kysely are powerful extensions that modify or enhance query behavior. Each plugin is implemented as a class that conforms to the KyselyPlugin interface.

Adding Plugins

To use plugins, add them to your Kysely database instance configuration:

const db = new Kysely<Database>({
  dialect: new PostgresDialect({
    database: 'kysely_test',
    host: 'localhost',
  }),
  plugins: [
    // Add plugins here
    new CamelCasePlugin(),
  ],
})

For implementation examples and advanced usage, see:

• Deduplicating Joins Recipe
• DeduplicateJoinsPlugin API documentation

Available Built-in Plugins

CamelCasePlugin

The CamelCasePlugin automatically handles the conversion between database and JavaScript naming conventions:

• Purpose: Transforms snake_case database identifiers to camelCase in your JavaScript code
• Use Case: Ideal when working with databases that follow SQL naming conventions (snake_case) while maintaining JavaScript conventions (camelCase) in your application code
• Example:
  • Database column: user_name
  • JavaScript property: userName

For detailed configuration options, refer to the CamelCasePlugin API documentation.

DeduplicateJoinsPlugin

The DeduplicateJoinsPlugin optimizes your queries by eliminating redundant join operations:

• Purpose: Automatically removes duplicate JOIN clauses from your queries
• Benefits:
  • Improves query performance
  • Reduces complexity in generated SQL
  • Prevents unintended cartesian products
• Use Case: Particularly valuable in complex queries with multiple joins that might accidentally introduce duplicates