如何通过子数组中项目的 ID 获取 firestore 文档

Question

First of all sorry if the title is not very explicit (I don't speak English very well).

I have a Firebase firestore collection. In this collection all the documents have an array.

Here is an example of how the documents are structured:

• Document

  • Id

  • Array

    • Item1

      • Item1Id

    • Item2

      • Item2Id

I have the Id of an item of the array (eg 'Item1Id') and I want to fetch all the documents in which the array contains an item with this Id.

How can I do that?

Answer 1

You can't. This page explains how to perform queries on Firestore: https://firebase.google.com/docs/firestore/query-data/queries

array-contains will return documents that have an array containing the itemId , but it doesn't work with nested data.

A solution would be to create an itemIds array in your document that simply contains the list of itemIds, and perform the query on that field.