Method countBy

packages/mongodb/src/MongoEntityManager.ts:69–111

* @inheritDoc

(
    entityName: EntityName<Entity>,
    groupBy: EntityKey<Entity> | readonly EntityKey<Entity>[],
    options: CountByOptions<Entity> = {},
  )

   * @inheritDoc
   */
  override async countBy<Entity extends object>(
    entityName: EntityName<Entity>,
    groupBy: EntityKey<Entity> | readonly EntityKey<Entity>[],
    options: CountByOptions<Entity> = {},
  ): Promise<Dictionary<number>> {
    const em = this.getContext(false) as MongoEntityManager;
    options = { ...options };
    em.prepareOptions(options);
    const meta = em.getMetadata().find(entityName)!;
    const fields = Utils.asArray(groupBy);

    if (options.having) {
      throw new Error('The `having` option is not supported for MongoDB in `countBy`.');
    }

    await em.tryFlush(entityName, options);
    const rawWhere = options.where;
    const where = await em.processWhere(entityName, rawWhere ?? ({} as FilterQuery<Entity>), options as any, 'read');
    const renamedWhere = em.getDriver().renameFields(meta.class, where as Entity, true);

    const fieldNames = fields.map(f => meta.properties[f as EntityKey<Entity>]?.fieldNames?.[0] ?? f);
    const groupId =
      fieldNames.length === 1 ? `$${fieldNames[0]}` : Object.fromEntries(fieldNames.map(f => [f, `$${f}`]));

    const pipeline: Dictionary[] = [];

    if (renamedWhere && Object.keys(renamedWhere).length > 0) {
      pipeline.push({ $match: renamedWhere });
    }

    pipeline.push({ $group: { _id: groupId, count: { $sum: 1 } } });

    const rows = await em.getDriver().aggregate(meta.class, pipeline, em.getTransactionContext(), em.signal);
    const results: Dictionary<number> = {};

    for (const row of rows) {
      const key =
        fieldNames.length === 1 ? String(row._id) : fieldNames.map(f => String(row._id[f])).join(Utils.PK_SEPARATOR);
      results[key] = +row.count;
    }

    return results;
  }

  /**
   * @inheritDoc