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    Class CamelCasePlugin

    A plugin that converts snake_case identifiers in the database into camelCase in the JavaScript side.

    For example let's assume we have a table called person_table with columns first_name and last_name in the database. When using CamelCasePlugin we would setup Kysely like this:

    import * as Sqlite from 'better-sqlite3'
    import { CamelCasePlugin, Kysely, SqliteDialect } from 'kysely'

    interface CamelCasedDatabase {
      userMetadata: {
        firstName: string
        lastName: string
      }
    }

    const db = new Kysely<CamelCasedDatabase>({
      dialect: new SqliteDialect({
        database: new Sqlite(':memory:'),
      }),
      plugins: [new CamelCasePlugin()],
    })

    const person = await db.selectFrom('userMetadata')
      .where('firstName', '=', 'Arnold')
      .select(['firstName', 'lastName'])
      .executeTakeFirst()

    if (person) {
      console.log(person.firstName)
    }

    The generated SQL (SQLite):

    select "first_name", "last_name" from "user_metadata" where "first_name" = ?

    As you can see from the example, everything needs to be defined in camelCase in the TypeScript code: table names, columns, schemas, everything. When using the CamelCasePlugin Kysely works as if the database was defined in camelCase.

    There are various options you can give to the plugin to modify the way identifiers are converted. See CamelCasePluginOptions. If those options are not enough, you can override this plugin's snakeCase and camelCase methods to make the conversion exactly the way you like:

    class MyCamelCasePlugin extends CamelCasePlugin {
      protected override snakeCase(str: string): string {
        // ...

        return str
      }

      protected override camelCase(str: string): string {
        // ...

        return str
      }
    }

    Implements

    Index

    Constructors

    constructor

    Properties

    opt

    Methods

    camelCase mapRow snakeCase transformQuery transformResult

    Constructors

    Properties

    opt: CamelCasePluginOptions = {}

    Methods

    • 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

      Returns RootOperationNode

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