CODEWITHSUNDEEP
wpfmvvmbindingtabitem
user2029929
user2029929

Reputation: 18

Multiple TabItems bound to same ViewModel are not updating the first time a tab is selected

I have a tabcontrol with 3 tabs on it. Each tabitem contains a different contentcontrol, all of which are bound to the same ViewModel, and there are some items in all 3 contentcontrols that are bound to the same property.

My problem is, if I change a comboBox on the initial tab, that change is not reflected on the other tabs, they still have their SelectedItem set to the default value. This only happens the first time I switch to that tab. After I have selected a tab once, everything works as expected; changes made on one tab are reflected on the other tab.

I am trying to avoid too much code-behind, and I have searched and tried all of the solutions regarding delaying of the binding, or updating the binding when the tab is selected, but I have had no luck.

Here is my TabControl:

<TabControl Grid.Row="1" Margin="0,10">
    <TabItem Header="Tab1" IsSelected="True">
        <ContentControl Content="{Binding}" ContentTemplate="{StaticResource Tab1}" />
    </TabItem>
    <TabItem Header="Tab2">
        <ContentControl Content="{Binding}" ContentTemplate="{StaticResource Tab2}" />
    </TabItem>
    <TabItem Header="Tab3">
        <ContentControl Content="{Binding}" ContentTemplate="{StaticResource Tab}" />
    </TabItem>
</TabControl>

And here is one of the ContentControls:

<DataTemplate x:Key="Tab3" DataType="{x:Type vm:MainViewModel}">
<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition />
        <ColumnDefinition />
        <ColumnDefinition />
    </Grid.ColumnDefinitions>
    <Grid.RowDefinitions>
        <RowDefinition />
        <RowDefinition />
        <RowDefinition />
        <RowDefinition />
        <RowDefinition />
    </Grid.RowDefinitions>
    <Label Grid.Column="0" Grid.Row="0" Content="Flow" Style="{StaticResource tabLabel}" />
    <TextBox Grid.Column="1" Grid.Row="0" Style="{StaticResource tabTextBox}" />
    <ComboBox Grid.Column="2" Grid.Row="0" Style="{StaticResource tabUnitComboBox}" ItemsSource="{Binding DataList1}" DisplayMemberPath="Name" SelectedItem="{Binding SelectedData1}" />
    <ComboBox Grid.Column="0" Grid.Row="1" Style="{StaticResource tabComboBox}" ItemsSource="{Binding DataList2}" DisplayMemberPath="Name" SelectedItem="{Binding SelectedData2}" />
    <TextBox Grid.Column="1" Grid.Row="1" Style="{StaticResource tabTextBox}" />
    <Label Grid.Column="2" Grid.Row="1" Content="m³/h" Style="{StaticResource tabUnitLabel}" Visibility="{Binding SelectedData2, Converter={StaticResource VisibilityConverter}}" />
    <ComboBox Grid.Column="0" Grid.Row="2" Style="{StaticResource tabComboBox}" ItemsSource="{Binding DataList3}" SelectedItem="{Binding SelectedData3}" />
    <TextBox Grid.Column="1" Grid.Row="2" Style="{StaticResource tabTextBox}" />
    <ComboBox Grid.Column="2" Grid.Row="2" Style="{StaticResource tabUnitComboBox}" ItemsSource="{Binding DataList4}" DisplayMemberPath="Name" SelectedItem="{Binding SelectedData4}" />
    <Label Grid.Column="0" Grid.Row="3" Content="Temperature" Style="{StaticResource tabLabel}" />
    <TextBox Grid.Column="1" Grid.Row="3" Style="{StaticResource tabTextBox}" />
    <ComboBox Grid.Column="2" Grid.Row="3" Style="{StaticResource tabUnitComboBox}" ItemsSource="{Binding DataList5}" DisplayMemberPath="Name" SelectedItem="{Binding SelectedData5}" />
</Grid>
</DataTemplate>

The ViewModel is pretty much standard, inheriting from ObservableObject and implementing OnPropertyChanged. As I said, everything works perfectly after selecting a tab once, but I would really like to get it working from the start.

Any suggestions would be greatly appreciated. Thanks.

Upvotes: 0

Views: 449

Answers (1)

paparazzo
paparazzo

Reputation: 45096

In case you want to use that comment as and answer

Are you by any chance just starting with assigning the backing field.
Not firing INPC on the initial load.

Upvotes: 1

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