Method joinAndSelect

packages/sql/src/query/QueryBuilder.ts:1172–1234

* Adds a JOIN clause and automatically selects the joined entity's fields. * This is useful for eager loading related entities. * * @example * ```ts * const qb = em.createQueryBuilder(Book, 'b'); * qb.select('*') * .joinAndSelect('b.author', 'a') * .where({ 'a.name': 'Joh

(
    field: Field | [Field, RawQueryFragment | QueryBuilder<any>],
    alias: Alias,
    cond: JoinCondition<JoinedEntityType<Entity, Context, Field & string>, Alias> = {} as JoinCondition<
      JoinedEntityType<Entity, Context, Field & string>,
      Alias
    >,
    type = JoinType.innerJoin,
    path?: string,
    fields?: JoinFields,
    schema?: string,
  )

   * ```
   */
  joinAndSelect<
    Field extends QBField<Entity, RootAlias, Context>,
    Alias extends string,
    const JoinFields extends
      | readonly [
          JoinSelectField<JoinedEntityType<Entity, Context, Field & string>, Alias>,
          ...JoinSelectField<JoinedEntityType<Entity, Context, Field & string>, Alias>[],
        ]
      | undefined = undefined,
  >(
    field: Field | [Field, RawQueryFragment | QueryBuilder<any>],
    alias: Alias,
    cond: JoinCondition<JoinedEntityType<Entity, Context, Field & string>, Alias> = {} as JoinCondition<
      JoinedEntityType<Entity, Context, Field & string>,
      Alias
    >,
    type = JoinType.innerJoin,
    path?: string,
    fields?: JoinFields,
    schema?: string,
  ): SelectQueryBuilder<
    Entity,
    RootAlias,
    ModifyHint<RootAlias, Context, Hint, Field, true> & {},
    ModifyContext<Entity, Context, Field, Alias, true>,
    RawAliases,
    ModifyFields<Fields, RootAlias, Context, Field, Alias, JoinFields>,
    CTEs
  > {
    if (!this.#state.type) {
      this.select('*');
    }

    let subquery: string | undefined;

    if (Array.isArray(field)) {
      const rawFragment = field[1] instanceof QueryBuilder ? field[1].toRaw() : field[1];
      subquery = this.platform.formatQuery(rawFragment.sql, rawFragment.params);
      field = field[0];
    }

    const { prop, key } = this.joinReference(field as string, alias, cond, type, path, schema, subquery);
    const [fromAlias] = this.helper.splitField(field as string as EntityKey<Entity>);

    if (subquery) {
      this.#state.joins[key].subquery = subquery;
    }

    const populate = this.#state.joinedProps.get(fromAlias);
    const item = { field: prop.name, strategy: LoadStrategy.JOINED, children: [] };

    if (populate) {
      populate.children!.push(item);
    } else {
      // root entity
      this.#state.populate.push(item);
    }