Flutter - Adding Container (widget) in GridView when click a button?

Question

I wanted to add a container widget in the GridView when a button is clicked. I was able to do this with the column widget but could not do it with GridView.

import 'package:flutter/material.dart';

List<Widget> gridChild = [
  Container(
    margin: EdgeInsets.all(8.0),
    width: 30.0,
    height: 50.0,
    color: Colors.green,
  ),
  Container(
    margin: EdgeInsets.all(8.0),
    width: 30.0,
    height: 50.0,
    color: Colors.green,
  ),
  Container(
    margin: EdgeInsets.all(8.0),
    width: 30.0,
    height: 50.0,
    color: Colors.green,
  ),
  Container(
    margin: EdgeInsets.all(8.0),
    width: 30.0,
    height: 50.0,
    color: Colors.green,
  ),
  Container(
    margin: EdgeInsets.all(8.0),
    width: 30.0,
    height: 50.0,
    color: Colors.green,
  ),
];

class Grid extends StatefulWidget {
  @override
  _GridState createState() => _GridState();
}

class _GridState extends State<Grid> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: FloatingActionButton(
        backgroundColor: Colors.red,
        child: Icon(Icons.add),
        onPressed: () {
          setState(() {
            gridChild.add(Container(
              margin: EdgeInsets.all(8.0),
              width: 30.0,
              height: 50.0,
              color: Colors.green,
            ));
            print(gridChild.length);
          });
        },
      ),
      body: Container(
        child: GridView.count(
          crossAxisCount: 2,
          children: gridChild,
        ),
      ),
    );
  }
}

What I did was that I added a container in the widget list. The length of the list increases as I click the botton but the container was not added on the screen. It didn't work even though I put the function inside the setState().

I would really appreciate your help.

Josteve Adekanbi · Accepted Answer · 2020-04-29 15:01:29Z

3

This works...

class Grid extends StatefulWidget {
  @override
  _GridState createState() => _GridState();
}

class _GridState extends State<Grid> {

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: FloatingActionButton(
        backgroundColor: Colors.red,
        child: Icon(Icons.add),
        onPressed: () {
          setState(() {
            gridChild.add(Container(
              margin: EdgeInsets.all(8.0),
              width: 30.0,
              height: 50.0,
              color: Colors.green,
            ));
          });
        },
      ),
      body: Container(
        child: GridView.count(
          crossAxisCount: 2,
          children: List.generate(gridChild.length, (index) => gridChild[index]),
        ),
      ),
    );
  }
}

Output:

answered Apr 29, 2020 at 15:01

Josteve Adekanbi

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1 Comment

Yin Over a year ago

why need List.generate to copy the list ??

aldobaie · Accepted Answer · 2020-04-29 13:23:22Z

0

Use GridView.builder in the body. It should fix your problem. I don't really know why, but I know it works. Hopefully someone can update this answer and provide an explanation.

GridView.builder(
        itemCount: gridChild.length,
        gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
          crossAxisCount: 2,
        ),
        itemBuilder: (BuildContext context, int index){
          return gridChild[index];
        },
      ),

answered Apr 29, 2020 at 13:23

aldobaie

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Comments

DharmanBot · Accepted Answer · 2022-05-01 09:37:59Z

0

You can do it by calling the setstate method.

while clicking on the button just add a widget to the list and use the setstate after adding to the list. Basically setstate will rebuild the screen.

edited May 1, 2022 at 9:37

DharmanBot

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answered May 1, 2022 at 9:31

BC TUBE

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