如何在 firebase firestore 中使用 isEqualTo 和 isNotEqualTo 查询数据

Question

The below query stop working when I add .where('user_id', isNotEqualTo: currentUser..id) How can i fetch data with isEqualTo and isNotEqualTo in firebase firestore?

  Future<int> unreadMessages(String id) async {
    int message = 0;
    await messageRef
        .doc(id)
        .collection('items')
        .where('read', isEqualTo: 0)
        .where('user_id', isNotEqualTo:10)
        .get()
        .then((value) {
      message = value.docs.length;
    });
    return message;
  }

Answer 1

You need to create a composite index if you combine equality operators with inequality operators.

The official documentation describes this.

https://firebase.google.com/docs/firestore/query-data/queries#compound_queries

There is probably an error text in your console that inform you about this, even with a direct link you can click on that creates that index.