如何使用一个绑定多个文本框来分隔 WPF XAML 中的三位数字？

Question

I use C# WPF in Visual Studio 2019

I want to display my TextBoxes values as Thousands decimal separated like this 1500.9 => 1,500.9

I Choose Validation Rules and Binding for this problem because I don't want to use C# Code Behind and Another point is that this option alone does nothing for a text box

 StringFormat="0,0.0" 

What is My Problem :

I thought Binding in Validation Rule uses this type of property for formatting, I did bind all of my textboxes to my property and now all text boxes have the same value even when I change one of them enter image description here

My Project :

here is my Model name as Validator.cs :

namespace WpfApp5
{
    public class Validator
    {
        public double dbl_numeric { get; set; }
    }
}

My window for binding textboxes:

<Window x:Class="WpfApp5.Budget_Default"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:gif="http://wpfanimatedgif.codeplex.com"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp5"
        mc:Ignorable="d"
        xmlns:xctk="http://schemas.xceed.com/wpf/xaml/toolkit"
          
           xmlns:validate="clr-namespace:WpfApp5.Validation"
             
        AllowDrop="True"
        Height="550" Width="1033" >
    <Grid x:Name="mygrid">   
                 
         <TextBox x:Name="TextBox1"  >
            <Binding Path = "dbl_numeric" UpdateSourceTrigger = "PropertyChanged" StringFormat="0,0.0">
                <Binding.ValidationRules>
                    <ExceptionValidationRule ValidatesOnTargetUpdated = "True"/>
                    <validate:RequeredViladation/>
                </Binding.ValidationRules>
            </Binding>
        </TextBox>
        
         <TextBox x:Name="TextBox2"  >
            <Binding Path = "dbl_numeric" UpdateSourceTrigger = "PropertyChanged" StringFormat="0,0.0">
                <Binding.ValidationRules>
                    <ExceptionValidationRule ValidatesOnTargetUpdated = "True"/>
                    <validate:RequeredViladation/>
                </Binding.ValidationRules>
            </Binding>
        </TextBox>
        
          <TextBox x:Name="TextBox3"  >
            <Binding Path = "dbl_numeric" UpdateSourceTrigger = "PropertyChanged" StringFormat="0,0.0">
                <Binding.ValidationRules>
                    <ExceptionValidationRule ValidatesOnTargetUpdated = "True"/>
                    <validate:RequeredViladation/>
                </Binding.ValidationRules>
            </Binding>
        </TextBox>
</Grid>

What I need :

How to use Validation Rule or something to Display Thousands of Separated decimal numbers to use strings format for my textboxes

long story short: Each textbox should be separated into 3 digits, 3 digits for its own value only

1500.9 => 1,500.9

Answer 1

If all you want is to format the value bound to the textbox, this would suffice:

<TextBox Text="{Binding Path=dbl_numeric,StringFormat={}{0:N2}}" />

This will give you a culture specific separator for thousands, and two decimal places.

Validation is another topic. Note that out of the box, WPF will check if a value can be parsed as a double, and put a red border around a textbox if, for example, you input text. You may want to set UpdateSourceTrigger to LostFocus if you want to allow a user to type in a complete value before validating. If you have other validation needs, you will have to manually add this.

You three text boxes are currently all bound to the same value in the model (which typically would be a view model in WPF).