Flutter FirebaseAnimatedList 查询无法正常工作

Question

I tried to fetch some data from the firebase realtime database using a FirebaseAnimatedList() using a search query which should be query : ref.child("users").child(userPath).orderByChild("id").equalTo(userID) but instead of that query works without second child like this query : ref.child("users").orderByChild("id").equalTo(userID)

And it seems like when data is passed .equalTo(userID) if passed userID is not found in the database it loads a blank container I'm looking for a way to avoid loading a blank container and return a custom view if there's no value that matches .equalTo(userID)

realtime database example :

{
  "users" : {
    "user1" : {
      "lname" : "dee",
      "id" : "12"
    },
    "user2" : {
      "lname" : "nee",
      "id" : "13"
    },
    "user3" : {
      "lname" : "lee",
      "id" : "14"
    },
    "user4" : {
      "lname" : "bree",
      "id" : "15"
    }
  }

Code :

FirebaseAnimatedList(
        query: ref.child("users").orderByChild("id").equalTo(this.userid),
        itemBuilder: (BuildContext context, DataSnapshot snapshot,
            Animation<double> animation, int index) {
          return SizeTransition(
            sizeFactor: animation,
            axis: Axis.horizontal,
            axisAlignment: -0.8,
            child: Column(
              textDirection: TextDirection.ltr,
              verticalDirection: VerticalDirection.down,
              children: <Widget>[
                SizedBox(
                  height: 100.0,
                ),
                Text(
                  "User ID : " + snapshot.value["id"],
                ),
                SizedBox(
                  height: 50.0,
                ),
              ],
            ),
          );
        }));

Answer 1

The query is actually correct, to be able to access the id using orderByChild("id") , you dont need to use another child() method.

I'm looking for a way to avoid loading a blank container and return a custom view

FirebaseAnimatedList(
        query: ref.child("users").orderByChild("id").equalTo(this.userid),
        itemBuilder: (BuildContext context, DataSnapshot snapshot,
            Animation<double> animation, int index) {
         if(snapshot.value != null){
          return SizeTransition(
            sizeFactor: animation,
            axis: Axis.horizontal,
            axisAlignment: -0.8,
            child: Column(
              textDirection: TextDirection.ltr,
              verticalDirection: VerticalDirection.down,
              children: <Widget>[
                SizedBox(
                  height: 100.0,
                ),
                Text(
                  "User ID : " + snapshot.value["id"],
                ),
                SizedBox(
                  height: 50.0,
                ),
              ],
            ),
          );
         }
         else{
             return Text("no Data");
            }
        return CircularProgressIndicator();
        }));