Is OnDeactivate only called when explicit call Conductor.DeactivateItem?

[GF-Huang]

My TabControl is manual define items rather than ItemsSource binding. If I want my TabItem's view model OnDeactivate get called when the another TabItem selected, how can I do?

[canton7]

The Conductor classes all have special logic to activate and deactivate their children when appropriate. If you're not using this, you'll have to write that logic yourself.

One thing you might be able to do is:

public class ParentViewModel : Conductor.Collections.OneActive<IScreen>
{
    public AViewModel A { get; }
    public BViewModel B { get; }

    public ParentViewModel()
    {
        A = ...
        B = ...

        this.Items.AddRange(A, B);
    }
}

<TabControl SelectedItem="{Binding ActiveItem}" .....
    <TabItem><ContentControl s:View.Model="{Binding A"}/></TabItem>
    <TabItem><ContentControl s:View.Model="{Binding B"}/></TabItem>
</TabControl>

(Untested).

So, your ViewModels exist as properties of the parent (which you bind to from your TabControl), but the parent is a conductor and those ViewModels are also added to the conductor's items. The TabControl's SelectedItem is bound to the conductor's ActiveItem. When the current tab changes, the TabControl will set the ActiveItem on the conductor, which will activate/deactive its children as appropriate.

[canton7]

What do you mean exactly, "but not works"? What makes you think that it isn't working?

Are there any binding errors in the Output window?

What is the RootViewModel in your code? For all I know, RootViewModel could be the expected value of that property.

[GF-Huang]

No binding errors, "not works" means OnDeactivate not called.

public class RootViewModel : Conductor<IScreen>.Collection.OneActive { 
   ...
   public RootViewModel(AViewModel avm, BViewModel bvm) {
        Items.AddRange(new IScreen[] { avm, bvm });
   }
}

<TabControl SelectedValue="{Binding ActiveItem}"
            SelectedValuePath="DataContext">
    <TabItem s:View.Model="{Binding AViewModel}" />
    <TabItem s:View.Model="{Binding BViewModel}" />
</TabControl>

[canton7]

Note, you don't have any code to set the AViewModel and BViewModel properties there.

Ah, the s:View.Model isn't setting the DataContext of your TabItem, just of its content. You might have to do <TabItem DataContext="{Binding AViewModel}" s:View.Model="{Binding AViewModel}"/>

[GF-Huang]

Note, you don't have any code to set the AViewModel and BViewModel properties there.

I had set, but it is omitted here.

Ah, the s:View.Model isn't setting the DataContext of your TabItem, just of its content. You might have to do

The DataContext="{Binding AViewModel}" will breaking the s:View.Model="{Binding AViewModel}" because the TabItem.DataContext pointing to AViewModel rather than RootViewModel.

[GF-Huang]

This works, thank you!

s:View.Model="{Binding DataContext.AViewModel, RelativeSource={RelativeSource AncestorType=TabControl}}"