Question 79024 in Flutter Question posted in
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How to count string in an List with Firebase Flutter

I have an list of string in List. But I want to count it and display it in the text. How can I achieve that?

         StreamBuilder<DocumentSnapshot?>(
                  stream: FirebaseFirestore.instance
                      .collection("groups")
                      .doc(groupId)
                      .snapshots(),
                  builder: (context, snapshot) {
                   //Get a snapShot
                    var countRoom = snapshot.data?['room'];
                    //Display a counted room
                    return Text(countRoom)
                   )
                 }

enter image description here

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2

Answers


  1. 0

    I want to count it (the list)

    If I correctly understand your question, you need to use the length property as follows:

    var countRoom = snapshot.data?['room'];
var countRoomLength = countRoom.length;

    If you want to count the unique elements in the List, see this SO answer.

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  2. 0

    If you want sum of the string in your list you can do this:

    var rooms = snapshot.data?['room'];
int countRoom = rooms.fold(0, (int previousValue, element) => previousValue + int.parse(element));

return Text("$countRoom")//show 2
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