Flutter FirebaseFirestore where 条件返回相关和不相关的值

Question

I am querying a firestore collection in Flutter using where and arrayContains, for some reason it is not working as expected for me.

      StreamBuilder(
          stream: (_searchTerm.length >= 3)
              ? FirebaseFirestore.instance.collection("users").snapshots()
              : FirebaseFirestore.instance
                  .collection('users')
                  .where('email', arrayContains: _searchTerm)
                  .snapshots(),
          builder: (ctx, snapshot) {
            if (snapshot.connectionState == ConnectionState.waiting) {
              return Center(
                child: CircularProgressIndicator(),
              );
            }
            final results = snapshot.data.docs;
            print(results.length);
            return ListView.builder(
              shrinkWrap: true,
              itemCount: results.length,
              itemBuilder: (ctx, index) => Text(
                results[index].data()['display-name'],
              ),
            );
          })

The _searchTerm variable is populated as I type in some values into the textfield and when it hits a length of three characters that's when the above query fires. For example when I type in test the query should only return the values that contain test in it, but I am getting the whole collection with and without the value test. Please advice!

EDIT - Posting a screenshot of my firestore data structure

Answer 1

When you do the following:

FirebaseFirestore.instance
  .collection('users')
  .where('email', arrayContains: _searchTerm)
  .snapshots(),

You are looking for documents inside the users collection that have _searchTerm as an item of the email array, property of a user document.

There are two problems:

1. I don't think the email property of your users is an array.
2. Firebase does not perform substring searches

I think you will need to use a third-party application for searches on Firestore. A popular one is Algolia that comes with a quite powerful FREE plan.