Show result in data grid depend on combo box selected value

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hi,
i am facing a problem i can not solve i searched a lot but it doesn't work, i using mvvm i successfully loaded all the employee details in my datagrid and i have a combobox loading it with gender to filter the datagrid rows with the gender but datagrid does not update to show the new list , i used Inotifychangedproperty but it is useless i showing my code to advice me

What I have tried:

C#

public EditaEmployeesViewModel()
{



	SelectionChangedCommand = new RelayCommand(cbGenderSelectedChanged);

	_EmployeeList = new ObservableCollection<Model.Employees> 
	(DataAccess.EmplyeeDatabaseLayer.GetEmployeeFromDataBase());

	_GenderList = new ObservableCollection<Model.Gender> 
	(DataAccess.GenderDataBaseLayer.GetGenderFromDataBase());
}

ObservableCollection<Model.Employees> _EmployeeList;
ObservableCollection<Model.Gender> _GenderList;

public RelayCommand SelectionChangedCommand { get; set; }

void cbGenderSelectedChanged(object parameter)
{
	_EmployeeList = new ObservableCollection<model.employees> 
	(DataAccess.EmplyeeDatabaseLayer.GetEmployeesWithGenderID(SelectedGenderID));
}

public ObservableCollection<model.employees> EmployeeList
{
	get
	{
		return _EmployeeList;
	}
	set
	{
		_EmployeeList = value;
		Notifypropertychange("EmployeeList");
	}
}

public ObservableCollection<model.gender> GenderList
{
	get
	{
		return _GenderList;
	}
	set
	{
		_GenderList = value;
		Notifypropertychange("GenderList");
	}
}

public event PropertyChangedEventHandler PropertyChanged;

private void Notifypropertychange(string propertyName)
{
	if (PropertyChanged != null)
	{
		PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
	}
}

here is my combobox and datagrid

XML

<ComboBox ItemsSource="{Binding GenderList,UpdateSourceTrigger=Explicit}" 
          DisplayMemberPath="GenderName" SelectedValuePath="ID"
          Grid.Column="1" Name="cbGender"  SelectedValue="{Binding 
          SelectedGenderID}"  IsSynchronizedWithCurrentItem="True" >
			<i:Interaction.Triggers>
				<i:EventTrigger EventName="SelectionChanged">
					<i:InvokeCommandAction  Command="{Binding 
					 SelectionChangedCommand}"/>
				</i:EventTrigger>
			</i:Interaction.Triggers>
		</ComboBox>

<DataGrid Grid.Row="2" AutoGenerateColumns="False" CanUserAddRows="False" 
          SelectedItem="{Binding SelectedEmployee}"
          ItemsSource="{Binding EmployeeList,UpdateSourceTrigger=PropertyChanged}"
          SelectionMode="Single" SelectedIndex="{Binding SelectedIndex}"
		  IsSynchronizedWithCurrentItem="True">

Posted 13-Dec-18 10:40am

Ramy82

Updated 13-Dec-18 20:05pm

Graeme_Grant

v4

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Graeme_Grant · Accepted Answer · 2018-12-13T20:06:00

You're breaking Data Binding rules when you select an item in your ComboBox.

C#

void cbGenderSelectedChanged(object parameter)
{
    _EmployeeList = new ObservableCollection<model.employees> 
    (DataAccess.EmplyeeDatabaseLayer.GetEmployeesWithGenderID(SelectedGenderID));
}

If you have a collection object bound to the UI via Data Binding, Recreating the collection will break the binding.

So to fix, you need to do something like:

C#

void cbGenderSelectedChanged(object parameter)
{
    _EmployeeList.Clear();
    for each (var item in DataAccess.EmplyeeDatabaseLayer
                                    .GetEmployeesWithGenderID(SelectedGenderID))
    {
        _EmployeeList.add(item);
    }
}