Flutter DataTable - how set column width?

Question

I use DataTable in my Flutter app. This is simple example of my code:

    DataTable(
          columns: [
            DataColumn(label: Text('Column1')),
            DataColumn(label: Text('Column2')),
            DataColumn(label: Text('Column3')),
          ],
          rows: [
            DataRow(cells: [
              DataCell(Text('1')),
              DataCell(Text('2')),
              DataCell(Text('6')),
            ]),
            DataRow(cells: [
              DataCell(Text('12')),
              DataCell(Text('John')),
              DataCell(Text('9')),
            ]),
          
          ],
        )

I need to:

-column1 to be 20% of the available width

-column1 to be 40% of the available width

-column1 to be 40% of the available width

How can I do this? Is it possible for DataTable?

Answer 1

By the above method it is possible to calculate the Column size with MediaQuery but most of the times the DataTable will not have the full screen width, so we cannot calculate.

You can use this package to set individual column widths.
https://pub.dev/packages/data_table_2

        DataColumn2(
            label: Text('#'),
            size: ColumnSize.S, // Small column
          ),

There is predefined sizes for Column like ColumnSize.M for medium, ColumnSize.L for Large. smRatio and lmRatio can be used to adjust the width if you wish to modify the default.

Answer 2

You can try something like this :

import 'package:flutter/material.dart';

void main() {
  runApp(MaterialApp(home: MyApp()));
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final double width = MediaQuery.of(context).size.width;
    return Scaffold(
      appBar: AppBar(
        title: const Text("Flutter Demo"),
      ),
      body: Container(
        width: width,
        child: DataTable(
          columnSpacing: 0,
          horizontalMargin: 0,
          columns: [
            DataColumn(
              label: Container(
                width: width * .2,
                child: Text('Column1'),
              ),
            ),
            DataColumn(
              label: Container(
                width: width * .4,
                child: Text('Column2'),
              ),
            ),
            DataColumn(
              label: Container(
                width: width * .4,
                child: Text('Column3'),
              ),
            ),
          ],
          rows: [
            DataRow(cells: [
              DataCell(Text('1')),
              DataCell(Text('2')),
              DataCell(Text('6')),
            ]),
            DataRow(cells: [
              DataCell(Text('12')),
              DataCell(Text('John')),
              DataCell(Text('9')),
            ]),
          ],
        ),
      ),
    );
  }
}