Interface KyselyPlugin

src/plugin/kysely-plugin.ts:7–69

import type { UnknownRow } from '../util/type-utils.js'

export interface KyselyPlugin {
  /**
   * This is called for each query before it is executed. You can modify the query by
   * transforming its {@link OperationNode} tree provided in {@link PluginTransformQueryArgs.node | args.node}
   * and returning the transformed tree. You'd usually want to use an {@link OperationNodeTransformer}
   * for this.
   *
   * If you need to pass some query-related data between this method and `transformResult` you
   * can use a `WeakMap` with {@link PluginTransformQueryArgs.queryId | args.queryId} as the key:
   *
   * ```ts
   * import type {
   *   KyselyPlugin,
   *   QueryResult,
   *   RootOperationNode,
   *   UnknownRow
   * } from 'kysely'
   *
   * interface MyData {
   *   // ...
   * }
   * const data = new WeakMap<any, MyData>()
   *
   * const plugin = {
   *   transformQuery(args: PluginTransformQueryArgs): RootOperationNode {
   *     const something: MyData = {}
   *
   *     // ...
   *
   *     data.set(args.queryId, something)
   *
   *     // ...
   *
   *     return args.node
   *   },
   *
   *   async transformResult(args: PluginTransformResultArgs): Promise<QueryResult<UnknownRow>> {
   *     // ...
   *
   *     const something = data.get(args.queryId)
   *
   *     // ...
   *
   *     return args.result
   *   }
   * } satisfies KyselyPlugin
   * ```
   *
   * You should use a `WeakMap` instead of a `Map` or some other strong references because `transformQuery`
   * is not always matched by a call to `transformResult` which would leave orphaned items in the map
   * and cause a memory leak.
   */
  transformQuery(args: PluginTransformQueryArgs): RootOperationNode

  /**
   * This method is called for each query after it has been executed. The result
   * of the query can be accessed through {@link PluginTransformResultArgs.result | args.result}.
   * You can modify the result and return the modifier result.