CODEWITHSUNDEEP
dartflutter
pallav bohara
pallav bohara

Reputation: 6789

Expanded widgets must be placed inside Flex widgets

New to flutter, can some one tells me whats wrong with below codeenter image description here

  class GamePage extends StatelessWidget {
  int _row;
  int _column;

  GamePage(this._row,this._column);

  @override
  Widget build(BuildContext context) {
    return new Material(
      color: Colors.deepPurpleAccent,
      child:new Expanded(
          child:new GridView.count(crossAxisCount: _column,children: new List.generate(_row*_column, (index) {
        return new Center(
            child: new CellWidget()
        );
      }),) )


    );
  }
}

Attaching error screenshot.

Upvotes: 82

Views: 79788

Answers (6)

M Azam Khan
M Azam Khan

Reputation: 380

In my case issue was solved

 Flex(
        direction: Axis.vertical,
        children: [
          Expanded(
            child: Text("Issue was solved"),
       )
     ])

Upvotes: 4

Abdur Rehman
Abdur Rehman

Reputation: 555

sometimes it can also happen if you have an expended widget inside the SingleChildScrollView widget, then it shows the blank screen. If you have any expended widget inside SingleChildScrollView remove it and it will solve the problem.

Before

  body: SingleChildScrollView(
     child: Column(
     children: [
      Container(),
       Expanded(
       child: Container(),
        ),
       ],
      ),
      ),

After

  body: SingleChildScrollView(
     child: Column(
     children: [
      Container(),
      Container(),
       ],
      ),
      ),

Upvotes: 1

josiah mpokera
josiah mpokera

Reputation: 11

You need to try using Flex Widget on that

Upvotes: 1

Adrien Arcuri
Adrien Arcuri

Reputation: 2410

Another simple example related to the error but with Expanded and ConstrainedBox :

The code:

Column(
  children:  [
    ConstrainedBox(
      child: Expanded(
        child: ...
      )
    )
  ]

The error message:

[...] Usually, this means that the Expanded widget has the wrong ancestor RenderObjectWidget. Typically, Expanded widgets are placed directly inside Flex widgets. The offending Expanded is currently placed inside a ConstrainedBox widget.

Why the code is the code not working properly ? In this example, Expanded must have the Column as direct Parent (which is a compatible parent type).

The solution:

Column(
  children:  [
   Expanded(
      child: ConstrainedBox(
        child: ...
      )
    )
  ]

Upvotes: 0

Suragch
Suragch

Reputation: 512416

Crash

This crashes because Expanded is not a descendant of a Flex widget:

Container(
  child: Expanded(
    child: MyWidget(),
  ),
)

Acceptable

Here Expanded is a descendant of Flex:

Flex(
  direction: Axis.horizontal,
  children: [
    Expanded(
      child: MyWidget(),
    ),
  ],
)

Row is also a Flex widget:

Row(
  children: [
    Expanded(
      child: MyWidget(),
    ),
  ],
)

And so is Column:

Column(
  children: [
    Expanded(
      child: MyWidget(),
    ),
  ],
)

Another option is to just get rid of the Expanded widget:

Container(
  child: MyWidget(),
)

Upvotes: 70

Shady Aziza
Shady Aziza

Reputation: 53337

You do not have a Flex ancestor.

An Expanded widget must be a descendant of a Row, Column, or Flex, and the path from the Expanded widget to its enclosing Row, Column, or Flex must contain only StatelessWidgets or StatefulWidgets (not other kinds of widgets, like RenderObjectWidgets).

I am not sure about the need for Expanded in your case. But removing it or wrapping it in a Column should fix the problem.

Upvotes: 85

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