Problem mit UpdateSourceTrigger = PropertyChanged und StringFormat in WPF

Ich habe ein Textfeld in meiner Anwendung, das Daten enthält, die an ein Dezimalfeld in meiner Klasse gebunden sind, und der Bindungsmodus ist wechselseitig. Ich verwende StringFormat = {0: c} zur Währungsformatierung.

Dies funktioniert einwandfrei, solange ich 'UpdateSourceTrigger' nicht berühre. Wenn ich UpdateSourceTrigger = PropertyChanged setze, wird die Formatierung des eingegebenen Texts abgebrochen.

hier ist mein Codebeispiel

Employee.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel;

namespace Converter
{
    public class Employee : INotifyPropertyChanged
    {
        int _employeeNumber;
        string _firstName;
        string _lastName;
        string _department;
        string _title;
        decimal _salary;

        public Employee()
        {
            _employeeNumber = 0;
            _firstName =
                _lastName =
                _department =
                _title = null;
        }
        public int EmployeeNumber
        {
            get { return _employeeNumber; }
            set 
            { 
                _employeeNumber = value;
                OnPropertyChanged("EmployeeNumber");
            }
        }
        public string FirstName
        {
            get { return _firstName; }
            set 
            { 
                _firstName = value;
                OnPropertyChanged("FirstName");
            }
        }

        public string LastName
        {
            get { return _lastName; }
            set 
            { 
                _lastName = value;
                OnPropertyChanged("LastName");
            }
        }

        public string Department
        {
            get { return _department; }
            set 
            { 
                _department = value;
                OnPropertyChanged("Department");
            }
        }

        public string Title
        {
            get { return _title + " salary: " + _salary.ToString(); }
            set 
            { 
                _title = value;
                OnPropertyChanged("Title");
            }
        }

        public decimal Salary
        {
            get { return _salary; }
            set
            {
                _salary = value;                
                OnPropertyChanged("Salary");
                OnPropertyChanged("Title");
            }
        }

        public override string ToString()
        {
            return String.Format("{0} {1} ({2})", FirstName, LastName, EmployeeNumber);
        }


        protected void OnPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChangedEventArgs args = new PropertyChangedEventArgs(propertyName);
                this.PropertyChanged(this, args);
            }
        }

        #region INotifyPropertyChanged Members

        public event PropertyChangedEventHandler PropertyChanged;

        #endregion
    }
}

EmployeeList.cs:

using System.Collections.ObjectModel;

namespace Converter
{
    public class EmployeeList : ObservableCollection<Employee>
    {
    }
}

Window1.xaml:

<Window x:Class="Converter.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:Converter"
    Title="Window1" Height="500" Width="500">
    <Window.Resources>
        <local:EmployeeList x:Key="myEmployeeList">
            <local:Employee EmployeeNumber="1" FirstName="John" LastName="Dow" Title="Accountant" Department="Payroll" Salary="25000.00" />
            <local:Employee EmployeeNumber="2" FirstName="Jane" LastName="Austin" Title="Account Executive" Department="Customer Management" Salary="25000.00" />
            <local:Employee EmployeeNumber="3" FirstName="Ralph" LastName="Emmerson" Title="QA Manager" Department="Product Development" Salary="25000.00" />
            <local:Employee EmployeeNumber="4" FirstName="Patrick" LastName="Fitzgerald" Title="QA Manager" Department="Product Development" Salary="25000.00" />
            <local:Employee EmployeeNumber="5" FirstName="Charles" LastName="Dickens" Title="QA Manager" Department="Product Development" Salary="25000.00" />            
        </local:EmployeeList>
        <local:StringToDecimalCurrencyConverter x:Key="StringToDecimalCurrencyConverter"></local:StringToDecimalCurrencyConverter>
    </Window.Resources>
    <Grid DataContext="{StaticResource myEmployeeList}">
        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="240" />
            <RowDefinition Height="45" />
        </Grid.RowDefinitions>
        <ListBox Name="employeeListBox"  ItemsSource="{Binding Path=., Mode=TwoWay}" Grid.Row="0" />
        <Grid Grid.Row="1"  DataContext="{Binding ElementName=employeeListBox, Path=SelectedItem, Mode=TwoWay}">
            <Grid.RowDefinitions>
                <RowDefinition Height="40" />
                <RowDefinition Height="40" />
                <RowDefinition Height="40" />
                <RowDefinition Height="40" />
                <RowDefinition Height="40" />
                <RowDefinition Height="40" />
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="80" />
                <ColumnDefinition Width="*" />
            </Grid.ColumnDefinitions>
            <Label Grid.Row="0" Grid.Column="0">First Name</Label>
            <Label Grid.Row="1" Grid.Column="0">Last Name</Label>
            <Label Grid.Row="2" Grid.Column="0">Title</Label>
            <Label Grid.Row="3" Grid.Column="0">Department</Label>
            <Label Grid.Row="4" Grid.Column="0">Salary</Label>

            <TextBox Grid.Row="0" Grid.Column="1" Text="{Binding Mode=TwoWay, Path=FirstName}" />
            <TextBox Grid.Row="1" Grid.Column="1" Text="{Binding Mode=TwoWay, Path=LastName}" />
            <TextBox Grid.Row="2" Grid.Column="1" Text="{Binding Mode=TwoWay, Path=Title}" />
            <TextBox Grid.Row="3" Grid.Column="1" Text="{Binding Mode=TwoWay,  Path=Department}" />
            <TextBox Grid.Row="4" Grid.Column="1"  Text="{Binding Mode=TwoWay, StringFormat=\{0:c\}, UpdateSourceTrigger=PropertyChanged, Path=Salary}" />
            <TextBlock Grid.Row="5" Grid.Column="1"  Text="{Binding Mode=OneWay, Converter={StaticResource StringToDecimalCurrencyConverter}, Path=Salary}" />
        </Grid>        
    </Grid>
</Window>

Wenn Sie 'UpdateSourceTrigger = PropertyChanged' aus dem obigen Code entfernen, funktioniert dies einwandfrei.

Ich habe auch versucht, Converter anstelle von StringFormat zu verwenden, und das Problem ist immer noch nicht gelöst.

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