I have a problem with the SelectedItem in my ComboBox.
<ComboBox Name="cbxSalesPeriods"
ItemsSource="{Binding SalesPeriods}"
DisplayMemberPath="displayPeriod"
SelectedItem="{Binding SelectedSalesPeriod}"
SelectedValuePath="displayPeriod"
IsSynchronizedWithCurrentItem="True"/>
If I open the ComboBox, I see the values.
If I select an item, the selected Item won't be shown.
Has anybody an idea?
In my ViewModel I have these two properties:
public ObservableCollection<SalesPeriodVM> SalesPeriods { get; private set; }
private SalesPeriodVM selectedSalesPeriod;
public SalesPeriodVM SelectedSalesPeriod
{
get { return selectedSalesPeriod; }
set
{
if (selectedSalesPeriod != value)
{
selectedSalesPeriod = value;
RaisePropertyChanged("SelectedSalesPeriod");
}
}
}
These are a few properties from the class :
public SalesPeriodVO Vo
{
get { return period; }
}
public int Year
{
get { return period.Year; }
set
{
if (period.Year != value)
{
period.Year = value;
RaisePropertyChanged("Year");
}
}
}
public int Month
{
get { return period.Month; }
set
{
if (period.Month != value)
{
period.Month = value;
RaisePropertyChanged("Month");
}
}
}
public string displayPeriod {
get
{
return this.ToString();
}
}
public override string ToString()
{
return String.Format("{0:D2}.{1}", Month, Year);
}
EDIT: The Following happens If I remove the Property DisplayMemberPath:
This question is related to
c#
wpf
data-binding
mvvm
binding
<!-- xaml code-->
<Grid>
<ComboBox Name="cmbData" SelectedItem="{Binding SelectedstudentInfo, Mode=OneWayToSource}" HorizontalAlignment="Left" Margin="225,150,0,0" VerticalAlignment="Top" Width="120" DisplayMemberPath="name" SelectedValuePath="id" SelectedIndex="0" />
<Button VerticalAlignment="Center" Margin="0,0,150,0" Height="40" Width="70" Click="Button_Click">OK</Button>
</Grid>
//student Class
public class Student
{
public int Id { set; get; }
public string name { set; get; }
}
//set 2 properties in MainWindow.xaml.cs Class
public ObservableCollection<Student> studentInfo { set; get; }
public Student SelectedstudentInfo { set; get; }
//MainWindow.xaml.cs Constructor
public MainWindow()
{
InitializeComponent();
bindCombo();
this.DataContext = this;
cmbData.ItemsSource = studentInfo;
}
//method to bind cobobox or you can fetch data from database in MainWindow.xaml.cs
public void bindCombo()
{
ObservableCollection<Student> studentList = new ObservableCollection<Student>();
studentList.Add(new Student { Id=0 ,name="==Select=="});
studentList.Add(new Student { Id = 1, name = "zoyeb" });
studentList.Add(new Student { Id = 2, name = "siddiq" });
studentList.Add(new Student { Id = 3, name = "James" });
studentInfo=studentList;
}
//button click to get selected student MainWindow.xaml.cs
private void Button_Click(object sender, RoutedEventArgs e)
{
Student student = SelectedstudentInfo;
if(student.Id ==0)
{
MessageBox.Show("select name from dropdown");
}
else
{
MessageBox.Show("Name :"+student.name + "Id :"+student.Id);
}
}
I had a similar problem where the SelectedItem-binding did not update when I selected something in the combobox. My problem was that I had to set UpdateSourceTrigger=PropertyChanged for the binding.
<ComboBox ItemsSource="{Binding SalesPeriods}"
SelectedItem="{Binding SelectedItem, UpdateSourceTrigger=PropertyChanged}" />
Source: Stackoverflow.com