subcollection() creates a detached pipeline aimed at a subcollection path relative to each parent document in the outer pipeline. The returned pipeline has no database instance and cannot be executed directly. Embed it in another pipeline with toScalarExpression() or toArrayExpression().

Import from the pipelines entry point:

import {
  subcollection,
  field,
  countAll,
  average,
} from '@react-native-firebase/firestore/pipelines';

Basic example

import { getFirestore } from '@react-native-firebase/firestore';
import {
  execute,
  field,
  subcollection,
  countAll,
  average,
} from '@react-native-firebase/firestore/pipelines';

const db = getFirestore('your-enterprise-database-id');

const snapshot = await execute(
  db
    .pipeline()
    .collection('restaurants')
    .addFields(
      subcollection('reviews')
        .aggregate(countAll().as('reviewCount'), average('rating').as('avgRating'))
        .toScalarExpression()
        .as('reviewSummary'),
    )
    .select('name', field('reviewSummary')),
);

snapshot.results.forEach(row => {
  const summary = row.data().reviewSummary;
  console.log(row.data().name, summary.reviewCount, summary.avgRating);
});

Options object

Pass a SubcollectionStageOptions object when you need raw stage options:

subcollection({ path: 'reviews', rawOptions: {} });

Related helpers

Helper	Use when
`subcollection`	Target a subcollection relative to each parent doc
`toScalarExpression()`	Embed a nested pipeline as a single scalar field
`toArrayExpression()`	Embed a nested pipeline as an array of documents
`SubcollectionStageOptions`	Options type for the subcollection source stage

Upstream reference

See the firebase-js-sdk subcollection declaration for overload signatures and nested pipeline usage.

subcollection

Basic example

Options object

Related helpers

Upstream reference

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