CODEWITHSUNDEEP
firebasefluttergoogle-cloud-firestore
Simran Aswani
Simran Aswani

Reputation: 1316

The method [] was called on Null while syncing Firestore using Flutter

I was trying to sync a users coins and I came across this error: The method [] was called on Null. How do I display his coins dynamically using Firestore? 

 Widget firestoreBuild2(BuildContext context) {
    return StreamBuilder(
      stream: Firestore.instance.collection('users').document('id').snapshots(),
      builder: (context, snapshot) {
        if (snapshot.hasError)
          return  Text('Error: ${snapshot.error}');
        switch (snapshot.connectionState) {
          case ConnectionState.waiting: return  Text('Loading...');
          default:
            var userDocument = snapshot.data;
            return  Text(
            userDocument["coins"],
            textAlign: TextAlign.center,
            style: TextStyle(
              fontFamily: AppTheme2.fontName,
              fontWeight: FontWeight.normal,
              fontSize: 24,
              letterSpacing: 0.0,
              color: AppTheme2.white,
           ),
          ); 
        }
      },
    );
  }
}

Upvotes: 0

Views: 554

Answers (2)

Simran Aswani
Simran Aswani

Reputation: 1316

Turns out the reason this was happening is because I was fetching a string 'id' rather than my variable id, which is why it was causing a null error.

Upvotes: 1

Kris
Kris

Reputation: 3371

snapshot.connectionState has four possible values: none, waiting, active, or done. I'm not sure what the relationship is between the connection state and whether the snapshot has data, exactly.

But one thing you can do is check if snapshot.hasData, which will return false if snapshot.data is null. 

Widget firestoreBuild2(BuildContext context) {
    return StreamBuilder(
      stream: Firestore.instance.collection('users').document('id').snapshots(),
      builder: (context, snapshot) {
        if (!snapshot.hasData)
          return  Text('Loading ...');

        var userDocument = snapshot.data;
        return  Text(
          userDocument["coins"],
          textAlign: TextAlign.center,
          style: TextStyle(
            fontFamily: AppTheme2.fontName,
            fontWeight: FontWeight.normal,
            fontSize: 24,
            letterSpacing: 0.0,
            color: AppTheme2.white,
          ), 
        );
      },
    );
  }
}

Upvotes: 0

Related Questions