Method addPolymorphicJoin

packages/sql/src/query/QueryBuilder.ts:2413–2437

* Registers a join for a specific polymorphic target type. * Used by the driver to create per-target LEFT JOINs for JOINED loading. * @internal

(
    prop: EntityProperty,
    targetMeta: EntityMetadata,
    ownerAlias: string,
    alias: string,
    type: JoinType,
    path: string,
    schema?: string,
  )

   * @internal
   */
  addPolymorphicJoin(
    prop: EntityProperty,
    targetMeta: EntityMetadata,
    ownerAlias: string,
    alias: string,
    type: JoinType,
    path: string,
    schema?: string,
  ): void {
    // Override referencedColumnNames to use the specific target's PK columns
    // (polymorphic targets may have different PK column names, e.g. org_id vs user_id)
    const referencedColumnNames = targetMeta.getPrimaryProps().flatMap(pk => pk.fieldNames);
    const targetProp = { ...prop, targetMeta, referencedColumnNames } as EntityProperty;
    const aliasedName = `${ownerAlias}.${prop.name}[${targetMeta.className}]#${alias}`;
    this.#state.joins[aliasedName] = this.helper.joinManyToOneReference(
      targetProp,
      ownerAlias,
      alias,
      type,
      {},
      schema,
    );
    this.#state.joins[aliasedName].path = path;
    this.createAlias(targetMeta.class, alias);
  }

  /**
   * @internal