CODEWITHSUNDEEP
flutterdart
Paul Rangger
Paul Rangger

Reputation: 97

What is causing the error "Return Type 'TableRow' isn't a 'Widget', as defined by method 'build'"

I'm creating an App in Flutter/Dart and I'm currently working on the layout of the App. I'm trying to create a standart Table Layout, which works perfectly, up until I want to outsource the code into different files. At this point I created a class extending StatelessWidget which overrides the built method returning a TableRow. At this point my IDE claims that 'TableRow' is not of type 'Widget'.

I tried using different approaches like Grid Layout and some tricks with Rows/Columns, but not a single one is actually the solution I'm searching for. I'm just trying to refactor the code into multiple files.

This code is now in a seperate file. While the TableRow was a direct child in the Table() it worked perfectly fine.

import 'package:flutter/material.dart';

class Test extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
        return TableRow(
            children: [
                TableCell(
                    child: Text("test"),
                ),
            ]
        )
    }
}

The file I'd call the method from would somewhat look like this:

Container(
     constraints: BoxConstraints(minWidth: 250, maxWidth: 300, maxHeight: 300),
     child: Table(
         children: [
             Test(),
             Test(),
             Test(),
             Test(),
         ],
     ),
 ),

I simply expected the TableRow to be recognized as a normal Widget as everything else is. TableCell for example is recognized as Widget. The error Message I get is "error: The return type 'TableRow' isn't a 'Widget', as defined by the method 'build'. (return_of_invalid_type at [projectname] lib/widgets/auth/shared/test.dart:12)". The error happens before compiling and gets marked by Android Studio.

Edit: Added code call

Upvotes: 4

Views: 4924

Answers (1)

jamesdlin
jamesdlin

Reputation: 89946

The error message tells you what's wrong: TableRow isn't a Widget.

If you look at the TableRow documentation, note that there is no "Inheritance" section that shows that it derives from Widget.

If you look at the Table documentation, note that children is a List<TableRow> and not a List<Widget>.

"Everything is a widget" is a hyperbole meant to get people to think of decomposing their UIs into composable widgets. Obviously there are some things that aren't Widgets (int, String, Function, Element, RenderObject, ...).

Upvotes: 8

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