Flutter RenderFlex children have non-zero flex but incoming height constraints are unbounded error

Question

I am trying to create this layout (avoid the erased part in blue background). Attaching my code too.

 class TasksScreen extends StatelessWidget { const TasksScreen({ Key ? key }): super(key: key); @override Widget build(BuildContext context) { return Scaffold( backgroundColor: Colors.lightBlueAccent, floatingActionButton: FloatingActionButton( backgroundColor: Colors.lightBlueAccent, onPressed: () {}, child: const Icon(Icons.add), ), body: Column( crossAxisAlignment: CrossAxisAlignment.start, children: [ Container( padding: const EdgeInsets.only( top: 60.0, bottom: 30.0, right: 30.0, left: 30.0), child: Column( crossAxisAlignment: CrossAxisAlignment.start, children: < Widget > [ const CircleAvatar( backgroundColor: Colors.white, child: Icon( Icons.list, color: Colors.lightBlueAccent, size: 30.0, ), radius: 30.0, ), const SizedBox( height: 10.0, ), const Text( 'TodoList', style: TextStyle( color: Colors.white, fontWeight: FontWeight.w700, fontSize: 50.0, ), ), const Text( '12 items', style: TextStyle( color: Colors.white, fontSize: 18.0, ), ), Expanded( child: Container( padding: const EdgeInsets.symmetric(horizontal: 20.0), decoration: const BoxDecoration( color: Colors.white, borderRadius: BorderRadius.only( topLeft: Radius.circular(20.0), topRight: Radius.circular(20.0)), ), ), ), ]), ), ], )); } }

I am getting the error "RenderFlex children have non-zero flex but incoming height constraints are unbounded error". I replaced the Expanded widget with Flexible . The app builds and I get the icons and text with the floating action button but I don't get the white container area. If I keep the Expanded , I get the full light blue screen.

How can i do this?

Answer 1

Do this instead! Containers are dumb, they will not know to what extend to fill up the space until you provide a width and a height!

In my case I used media query to determine the height of the container(white part)

Here is the code:

import 'package:flutter/material.dart';
import 'package:flutter/cupertino.dart';
class TasksScreen extends StatelessWidget {
  const TasksScreen({
    Key ? key
  }): super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        backgroundColor: Colors.lightBlueAccent,
        floatingActionButton: FloatingActionButton(
          backgroundColor: Colors.lightBlueAccent,
          onPressed: () {},
          child: const Icon(Icons.add),
        ),
        body: SingleChildScrollView(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              const  SizedBox(height: 50,),
              Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: < Widget > [
                    Padding(
                      padding: const EdgeInsets.only(left:30.0),
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: const[
                           CircleAvatar(
                            backgroundColor: Colors.white,
                            child: Icon(
                              Icons.list,
                              color: Colors.lightBlueAccent,
                              size: 30.0,
                            ),
                            radius: 30.0,
                          ),
                           SizedBox(
                            height: 10.0,
                          ),
                           Text(
                            'TodoList',
                            style: TextStyle(
                              color: Colors.white,
                              fontWeight: FontWeight.w700,
                              fontSize: 50.0,
                            ),
                          ),
                           Text(
                            '12 items',
                            style: TextStyle(
                              color: Colors.white,
                              fontSize: 18.0,
                            ),
                          ),
                        ],
                      ),
                    ),
                    Container(
                        height: MediaQuery.of(context).size.height,
                        decoration: const BoxDecoration(
                    color: Colors.white,
                    borderRadius: BorderRadius.only(
                        topLeft: Radius.circular(20.0),
                        topRight: Radius.circular(20.0)),
                        ),
                      ),
                  ]),
            ],
          ),
        ));
  }
}

And also I grouped the top part inside a column so that I could generalize the the paddings.

Cheers:)