How to allow only Positive decimal value in WPF DataGridTextColumn

Question

I want to allow only positive decimal value in DataGridTextColumn and if user enter .369 the system will show it 0.369 how it possible. I am new in WPF

Answer 1

Try this

XAML:

   <Window x:Class="SandBox.Window4"
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            xmlns:local="clr-namespace:SandBox"
            Title="Window4" Height="300" Width="300">
        <Grid>
            <Grid.RowDefinitions>
                <RowDefinition></RowDefinition>
            </Grid.RowDefinitions>
            <DataGrid x:Name="dg" Grid.Row="0" >
                <DataGrid.Columns>
                    <DataGridTemplateColumn Header="Quantity" Width="100">
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <TextBox Text="{Binding Path=Qty, Mode=TwoWay}" x:Name="tb" TextChanged="tb_TextChanged">

                                </TextBox>
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                </DataGrid.Columns>
            </DataGrid>
        </Grid>
    </Window>

This is the CodeBehind:

   using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Windows;
    using System.Windows.Controls;
    using System.Windows.Data;
    using System.Windows.Documents;
    using System.Windows.Input;
    using System.Windows.Media;
    using System.Windows.Media.Imaging;
    using System.Windows.Shapes;
    using System.Collections.ObjectModel;

    namespace SandBox
    {
        /// <summary>
        /// Interaction logic for Window4.xaml
        /// </summary>
        public partial class Window4 : Window
        {
            public ObservableCollection<ItemClass> Collection = new ObservableCollection<ItemClass>();
            public Window4()
            {
                InitializeComponent();
                //Collection.Add(new ItemClass("123"));
                //Collection.Add(new ItemClass("456"));
                Collection.Add(new ItemClass("123"));
                Collection.Add(new ItemClass("456"));
                dg.ItemsSource = Collection;
            }

            private void tb_TextChanged(object sender, TextChangedEventArgs e)
            {
                int result = 0;
                TextBox txt = sender as TextBox;
                if (txt != null)
                {
                    if (!int.TryParse(txt.Text, out result))
                    {
                        if(result >= 0)
                        {
                            txt.Text = txt.Text.Substring(0, txt.Text.Length - 1);
                            txt.CaretIndex = txt.Text.Length;
                        }
                    }
                }
            }
        }

        public class ItemClass
        {
            public string Qty { get; set; }
            public ItemClass(string qty)
            {
                Qty = qty;
            }
        }
    }

Answer 2

For this you might have to set appropriate StringFormat in TextColumn's Binding.

Try this...

   <Controls:DataGridTextColumn Header="Quantity"
                                Binding="{Binding Quantity, 
                                         StringFormat='{}{0:0.####}'}"/>

So now if user enter .897 and presses enter, the cell value will be shown as "0.897".