wpf Combobox Itemssource not binding within Listbox Data Template - wpf

Question

Please help to fix the below issue.
I have Combobox inside listbox item datatemplate so that I can load multiple combobox but same itemsource
<StackPanel>
<ListBox Width="400" Name="lstFiles" ItemsSource="{Binding}">
<ListBox.ItemTemplate>
<DataTemplate>
<Grid Name="dataGrid">
<Grid.RowDefinitions>
<RowDefinition/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<TextBox Name="dragFileName"
Margin="5,0,0,0"
Text="{Binding fileName, UpdateSourceTrigger=Default}" />
<ComboBox Grid.Row="0"
Grid.Column="1"
Margin="5,0,0,0"
Name="cboDragDocType"
ItemsSource="{Binding dragDocType, UpdateSourceTrigger=LostFocus, Mode=TwoWay}"
Text="{Binding dragDocTypeText}"
IsEditable="True"
IsReadOnly="True" />
<Button Name="dragDelBtn"
Grid.Column="2"
Height="20">X</Button>
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</StackPanel>
Data is loading in comboBox by using ObservableCollection property. In Initialize method i do for loop method to get multiple items.
Problem scenario: Select item from the dropdown1 --> then Select item from the dropdown2 -->Again click dropdown1, Now dropdown1 itemssource is empty.

Answer 1

You don't have a binding to the SelectedItem (or SelectedValue) property of the ComboBox. Therefore the value cannot be saved (or retrieved).
You need to add a property in your class that acts as the DataContext to hold the selected item of the ComboBox, for example:
<ComboBox Grid.Row="0"
...
SelectedItem="{Binding Path=SelectedDragDocType, UpdateSourceTrigger=LostFocus}" />
As a side-note having both IsEditable and IsReadOnly properties on the ComboBox set to true is pretty restrictive. Are you sure it is the intended behavior?