CODEWITHSUNDEEP
firebaseflutterdartgoogle-cloud-firestore
Mary X
Mary X

Reputation: 310

Dart - How to make StreamBuilder stop listening for events

I am using a StreamBuilder to access the contents of my Firestore database and create a list of List Tiles for such content. My problem is that whenever I click on a List Tile, it's like my StreamBuilder method gets called again and doubles the amount of List Tiles that I need in my list (since I am using the List.add() method).

How do I make StreamBuilders stop "re-building" or "listening"? I'm fairly new to Dart so I'm not sure how to approach this.

Here is the code that keeps getting repeated. (I have censored some information in places that contain "..." for the purpose of this post):

    var topics = new List();
    var messages = new List();
    var dates = new List();
    List<Widget> content = new List<Widget>();

    return new StreamBuilder<QuerySnapshot>(
        stream: Firestore.instance.collection("collection-id").snapshots(),
        builder: (context, snap) {
          //just add this line
          if (snap.data == null) return CircularProgressIndicator();

          for (int i = 0; i < snap.data.documents.length; i++) {
            topics.add(...);
            messages.add(snap.data.documents[i]["message"].toString());
            dates.add(...);
          }

          for (var i = 0; i < topics.length; i++) {
            content.add(new Container(
                child: new ListTile(
                  leading: Icon(Icons.events, color: Colors.black, size: 30,),
                  title: Text(topics[i].toString()),
                  subtitle: Text(messages[i].toString()),
                  onTap: () {
                    Navigator.push(context,
                      MaterialPageRoute(builder: (context) => ReadContent(topics[i], messages[i],dates[i])),
                    );
                  },
                ),
                decoration: new BoxDecoration(border: new Border(bottom: new BorderSide()))));
          }//for
          return new Column(children: content);
        });//StreamBuilder
}//showContent()

This is a snippet from Stateful widget where showContent() is called:

  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('App'),
      ),
      body: Center(
        child: new Container(
          child: new SingleChildScrollView(
            child: new Column(
              children: <Widget>[

                  showContent(context),
              ],
            ),
          ),
        ),
      ),
 );//Scaffold
}

Upvotes: 1

Views: 1449

Answers (1)

Shubham Gupta
Shubham Gupta

Reputation: 1997

One way to do that would be to clear your List when you are adding data to it. With your current approach if some new data also arrives the data will be appended to the List and result in data duplication.

for (int i = 0; i < snap.data.documents.length; i++) {
        topics.clear();//clear the items in list
        topics.add(...);
        messages.add(snap.data.documents[i]["message"].toString());
        dates.add(...);
      }

Upvotes: 2

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