how to fetch data from firestore array of a document with flutter? - firebase

Question

this is my users collection in cloud fire store:
users collection
this is the function that gets users from users collection in firestore
Stream<QuerySnapshot> fetchUsersInSearch() {
return Firestore.instance.collection('users').snapshots();
}
i use this method
final emailResults = snapshot.data.documents
.where((u) => u['email'].contains(query));
in the following streamBuilder to fetch users by their email.
i have this streamBuilder to populate the data on screen
return StreamBuilder<QuerySnapshot>(
stream: DatabaseService().fetchUsersInSearch(),
builder: (context, AsyncSnapshot<QuerySnapshot> snapshot) {
final emailResults = snapshot.data.documents
.where((u) => u['email'].contains(query));
if (!snapshot.hasData) {
return Container(
color: Theme.of(context).primaryColor,
child: Center(
child: Text(
'',
style: TextStyle(
fontSize: 16, color: Theme.of(context).primaryColor),
),
),
);
}
if (emailResults.length > 0) {
return Container(
color: Theme.of(context).primaryColor,
child: ListView(
children: emailResults
.map<Widget>((u) => GestureDetector(
child: Padding(
padding: const EdgeInsets.all(0.1),
child: Container(
padding: EdgeInsets.symmetric(vertical: 5),
decoration: BoxDecoration(
color: Theme.of(context).primaryColor,
border: Border(
bottom: BorderSide(
width: 0.3, color: Colors.grey[50]))),
child: ListTile(
leading: CircleAvatar(
backgroundColor:
Theme.of(context).primaryColor,
backgroundImage:
NetworkImage(u['userAvatarUrl']),
radius: 20,
),
title: Container(
padding: EdgeInsets.only(left: 10),
child: Column(
crossAxisAlignment:
CrossAxisAlignment.start,
children: [
Text(u['email'],
style: TextStyle(
fontSize: 16,
color: Theme.of(context)
.accentColor),
overflow: TextOverflow.ellipsis),
SizedBox(
height: 5,
),
],
),
),
),
),
),
onTap: () {
showUserProfile(u['id']);
},
))
.toList(),
),
);
} else {
return Container(
color: Theme.of(context).primaryColor,
child: Center(
child: Text(
'No results found',
style: TextStyle(
fontSize: 16,
color: Theme.of(context).accentColor,
),
),
),
);
}
});
this is working perfectly and fetching users inside a listView by their email...
p.s: the (query) is a string i type in a seach bar.
how can i make a query to fetch users by their otherUsernames...the second field in the screenshot of the users collection ?!
i tried this:
final otherUsernamesResults = snapshot.data.documents
.where((u) => u['otherUsernames'].contains(query));
but its returning this error:
The method 'contains' was called on null.
Receiver: null
Tried calling: contains("#username1")
what am i doing wrong here ?!!
any help would be much appreciated..

Answer 1

Try this:-
Stream<QuerySnapshot> getUsers() {
final usersCollection = FirebaseFirestore.instance.collection('users');
return usersCollection.where('otherUsernames', arrayContainsAny: ['username1', 'username2']);
}
For firestore version 0.16.0