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Flutter – 'List<Comment>' can't be assigned to the parameter type 'List<Widget>'

posts.dart file

return ListView(
  shrinkWrap: true, //for nested lists
  physics: const NeverScrollableScrollPhysics(),
  children: snapshot.data!.docs.map((doc) {
    //get the comment
    final commentData = doc.data() as Map<String, dynamic>;

    //return the comment
    return Comment(
      text: commentData["CommentText"], 
      user: commentData["CommentedBy"], 
      time: formatDate(commentData["CommentTime"]),
    );
  }).toList(),
);

comment.dart file

import 'package:flutter/material.dart';

class Comment extends StatelessWidget {
  final String text;
  final String user;
  final String time;
  const Comment({
    super.key,
    required this.text,
    required this.user,
    required this.time,
  });

  @override
  Widget build(BuildContext context) {
    return Container(
      decoration: BoxDecoration(
        color: Colors.grey[300],
        borderRadius: BorderRadius.circular(4),
      ),
      child: Column(
        children: [
          //comment
          Text(text),

          //user time
          Row(
            children: [
              Text(user),
              Text(" . "),
              Text(time),
            ],
          ),
        ],
      ),
    );
  }
}

Comment() class is not getting recognized by the ListView and to make it work I even put toList() method at the end of the bracket but it still gives the error I have written in the title.

You can also take a look at the comment.dart file which describes the Comment method. I’m confused as to why isn’t it exporting in the main file.

Tags:

2

Answers


  1. 0

    Could you provide detailed error messages and screenshots of the errors? Otherwise, it’s challenging for me to determine the issue you’re encountering. I’ve implemented a test case based on the code snippets you provided, and I didn’t encounter the error you mentioned.

    import 'package:flutter/material.dart';
    
    void main() {
      runApp(MyApp());
    }
    
    class CommentModel{
      final String text;
      final String user;
      final String time;
      const CommentModel({
        required this.text,
        required this.user,
        required this.time,
      });
    
    }
    
    class MyApp extends StatefulWidget {
      const MyApp({super.key});
    
      @override
      State<MyApp> createState() => _MyAppState();
    }
    
    class _MyAppState extends State<MyApp> {
      final List<CommentModel> comments = [
        CommentModel(
          text: "This is a comment",
          user: "User1",
          time: "12:00",
        ),
        CommentModel(
          text: "This is another comment",
          user: "User2",
          time: "12:01",
        ),
      ];
      @override
      Widget build(BuildContext context) {
        return MaterialApp(
          home: Scaffold(
            body: ListView(
              shrinkWrap: true, //for nested lists
              physics: const NeverScrollableScrollPhysics(),
              children:comments.map((doc) {
                //get the comment
                final commentData = doc;
                //return the comment
                return Comment(
                  text: commentData.text,
                  user: commentData.user,
                  time: commentData.time,
                );
              }).toList(),
            ),
          ),
        );
      }
    }
    
    
    class Comment extends StatelessWidget {
      final String text;
      final String user;
      final String time;
      const Comment({
        super.key,
        required this.text,
        required this.user,
        required this.time,
      });
    
      @override
      Widget build(BuildContext context) {
        return Container(
          decoration: BoxDecoration(
            color: Colors.grey[300],
            borderRadius: BorderRadius.circular(4),
          ),
          child: Column(
            children: [
              //comment
              Text(text),
    
              //user time
              Row(
                children: [
                  Text(user),
                  Text(" . "),
                  Text(time),
                ],
              ),
            ],
          ),
        );
      }
    }
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  2. 0

    Try to use listview of comment

    return ListView<Comment>(
  ..
)
    Login or Signup to reply.
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