Last Updated: 3/10/2026

kysely

• KyselyPlugin

Interface KyselyPlugin

interface KyselyPlugin {
    transformQuery(args: PluginTransformQueryArgs): RootOperationNode;
    transformResult(
        args: PluginTransformResultArgs,
    ): Promise<QueryResult<UnknownRow>>;
}

Implemented by

• CamelCasePlugin
• DeduplicateJoinsPlugin
• HandleEmptyInListsPlugin
• ParseJSONResultsPlugin
• WithSchemaPlugin

Index

Methods

transformQuery transformResult

Methods

transformQuery

• transformQuery(args: PluginTransformQueryArgs): RootOperationNode

  This is called for each query before it is executed. You can modify the query by transforming its OperationNode tree provided in args.node and returning the transformed tree. You’d usually want to use an OperationNodeTransformer for this.

  If you need to pass some query-related data between this method and transformResult you can use a WeakMap with args.queryId as the key:

  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.

  Parameters

  • args: PluginTransformQueryArgs

  Returns RootOperationNode

transformResult

• transformResult(
      args: PluginTransformResultArgs,
  ): Promise<QueryResult<UnknownRow>>

  This method is called for each query after it has been executed. The result of the query can be accessed through args.result. You can modify the result and return the modifier result.

  Parameters

  • args: PluginTransformResultArgs

  Returns Promise<QueryResult<UnknownRow>>

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Methods

transformQuerytransformResult