Method stream

packages/sql/src/query/QueryBuilder.ts:2538–2585

* Executes the query and returns an async iterable (async generator) that yields results one by one. * By default, the results are merged and mapped to entity instances, without adding them to the identity map. * You can disable merging and mapping by passing the options `{ mergeResults: false

(options?: QBStreamOptions)

   * ```
   */
  async *stream(options?: QBStreamOptions): AsyncIterableIterator<Loaded<Entity, Hint, Fields>> {
    options ??= {};
    options.mergeResults ??= true;
    options.mapResults ??= true;
    const chunkSize = options.chunkSize ?? 100;

    const query = this.toQuery();
    const loggerContext = { id: this.em?.id, ...this.loggerContext, ...this.#abortOptions };
    const res = this.getConnection().stream(query.sql, query.params, this.context, loggerContext, chunkSize);
    const meta = this.mainAlias.meta;

    if (options.rawResults || !meta) {
      yield* res as AsyncIterableIterator<Loaded<Entity, Hint, Fields>>;
      return;
    }

    const joinedProps = this.driver.joinedProps(meta, this.#state.populate);
    const stack = [] as EntityData<Entity>[];
    const hash = (data: EntityData<Entity>) => {
      return Utils.getPrimaryKeyHash(meta.primaryKeys.map(pk => data[pk as EntityKey]));
    };

    for await (const row of res) {
      const mapped = this.driver.mapResult<Entity>(row as Entity, meta, this.#state.populate, this as any)!;

      if (!options.mergeResults || joinedProps.length === 0) {
        yield this.mapResult(mapped, options.mapResults);
        continue;
      }

      if (stack.length > 0 && hash(stack[stack.length - 1]) !== hash(mapped)) {
        const res = this.driver.mergeJoinedResult(stack, this.mainAlias.meta, joinedProps);

        for (const row of res) {
          yield this.mapResult(row, options.mapResults);
        }

        stack.length = 0;
      }

      stack.push(mapped);
    }

    if (stack.length > 0) {
      const merged = this.driver.mergeJoinedResult(stack, this.mainAlias.meta, joinedProps);
      yield this.mapResult(merged[0], options.mapResults);
    }
  }

  /**
   * Alias for `qb.getResultList()`