Getting error; The operator '[]' isn't defined for the type 'Object? Function()'

Question

I am turning a stream into Widgets using the StreamBuilder, but I get my string in the operator highlighted and with the error:

The operator '[]' isn't defined for the type 'Object? Function()

This is the code:

void messageStream() async {
  await for (var snapshot in _firestore.collection('messages').snapshots()) {
    for (var message in snapshot.docs) {
      print(message.data());
    }
  }
}


    body: SafeArea(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: <Widget>[
          StreamBuilder<QuerySnapshot>(
            stream: _firestore.collection('messages').snapshots(),
            builder: (context, snapshot) { //This is where the second error appeared
              if (snapshot.hasData) {
                final messages = snapshot.data?.docs;
                List<Text> messageWidgets = [];
                for (var message in messages!) {
                  final messageText = message.data['text']; //These are where the errors can be found
                  final messageSender = message.data['sender'];//These are where the errors can be found.

                  final messageWidget = Text('$messageText from $messageSender');
                  messageWidgets.add(messageWidget);
                }
                return Column(
                  children: messageWidgets,
                );
              }
              return build(context);
            },
          ),

MendelG · Accepted Answer · 2022-11-22 21:49:12Z

2

.data is a function. So, you have to call it using parenthesis (). Additionally, you might have to cast the correct type using the as keyword.

Instead of:

final messageText = message.data['text'];
final messageSender = message.data['sender'];

Try:

final messageText = (message.data() as Map)['text'];
final messageSender = (message.data() as Map)['sender'];

Or: you can use .get():

final messageText = message.get('text');
final messageSender = message.get('sender');

edited Nov 22, 2022 at 21:49

answered Nov 22, 2022 at 21:41

MendelG

20.6k5 gold badges38 silver badges68 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Fred_Wolfe Over a year ago

I have edited my question it is about the last line of code where I return build(context), initially I had an error saying; "The body might complete normally, causing 'null' to be returned, but the return type, 'Widget', is a potentially non-nullable type" so I decided to do return build(context)... am I correct about this? or what should I have done if I wasn't

MendelG Over a year ago

@Fred_Wolfe Yes, you should add the return keyword to fix that error.

Collectives™ on Stack Overflow

Getting error; The operator '[]' isn't defined for the type 'Object? Function()'

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related