Error: Property 'docs' cannot be accessed on 'QuerySnapshot<Object?>?' bec-CodePudding

i'm working with firebase and flutter and i got this two error : (1) => Error: Property 'uid' cannot be accessed on 'User?' because it is potentially null (2) => Error: Property 'docs' cannot be accessed on 'QuerySnapshot<Object?>?' because it is potentially null

Widget build(BuildContext context) {
  return Scaffold(
    body: Container(
      decoration: BoxDecoration(color: Colors.pink),
      width: MediaQuery.of(context).size.width ,
      height: MediaQuery.of(context).size.height,
      child : Center(child: StreamBuilder(
        stream : FirebaseFirestore.instance.collection('Users')
        .doc(FirebaseAuth.instance.currentUser.uid) (1)
        .collection("Coins")
        .snapshots(),
        builder: (BuildContext context , 
            AsyncSnapshot<QuerySnapshot> snapshot ) {
              if(!snapshot.hasData){
                  return Center(
                    child: CircularProgressIndicator(),
                );  
              }
              return ListView(
                children: snapshot.data.docs.map((document) {  (2)
                  return Container(
                    child : Row(
                      children : [
                        Text("Coin Name :  "),
                        Text("Amount Owned : "),
                      ] ,
                    ),
                  ); 
                }).toList(),
              );
            }
        ),
        ),
    ),
  );
}

CodePudding user response：

To remove potential error you can apply a if condition before using the code that can give potential null error like

if(FirebaseAuth.instance.currentUser.uid!=null){....}

CodePudding user response：

This means the User can be null. To access a property on a nullable object, you need to use ?. (return null if null) or !. (throw an error if it's null). In most cases you should use ?..

FirebaseAuth.instance.currentUser?.uid
...
children: snapshot.data?.docs.map((document) {