WPF Tabcontrol: How to load multiple Tabitem from different view

Question

Suppose this code:

<TabControl>
            <TabItem>
                <Label Content="tab1"/>
            </TabItem>
            <TabItem>
                <Label Content="tab2"/>
            </TabItem>
            <TabItem>
                <Label Content="tab3"/>
            </TabItem>
</TabControl>

How can I extract tab2 and tab3 to a different xaml file and the result be something like this:

<TabControl>
            <TabItem>
                <Label Content="tab1"/>
            </TabItem>
            <views:MyView/>
</TabControl>

where MyView is something like:

<UserControl x:Class="WpfApp3.MyView"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:WpfApp3"
             mc:Ignorable="d" 
             d:DesignHeight="450" d:DesignWidth="800">

    <TabItem>
        <Label Content="tab2"/>
    </TabItem>
    <TabItem>
        <Label Content="tab3"/>
    </TabItem>

</UserControl>

Answer 1

It's difficult to set multiple TabItems in a single xaml.
If you just want to make your code more manageable, then I recommend defining the data for each tab in the user control, but still have the TabItem in the main tab control.
You could decompose the tab content into UserControl:

<UserControl x:Class="TabControlItemFromDifferentView.View1"  
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"  
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"  
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"   
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"   
             xmlns:local="clr-namespace:TabControlItemFromDifferentView"  
             mc:Ignorable="d"   
             d:DesignHeight="450" d:DesignWidth="800">  
    <Grid>  
        <Label Content="tab1"/>  
    </Grid>  
</UserControl>  

If you want to include a TabItem in a user control, you can do so by first creating the user control and then changing the type of the user control to the TabItem type (make sure in the xaml root node and in the code behind).
The "User Control" for each TabItem1 is TabItem type:

<TabItem x:Class="TabControlItemFromDifferentView.View2"  
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"  
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"  
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"   
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"   
             xmlns:local="clr-namespace:TabControlItemFromDifferentView"  
             mc:Ignorable="d"   
             d:DesignHeight="450" d:DesignWidth="800">  
    <Grid>  
        <TextBlock Text="Tab Data" />  
    </Grid>  
</TabItem>  

Code behind:

 public partial class View2 : TabItem  
  {  
    public View2()  
    {  
      InitializeComponent();  
    }  
  }  

MainWindow.xaml:

<Grid>  
        <TabControl>  
            <TabItem >  
                <local:View1/>  
            </TabItem>  
            <local:View2 Header="tab2"/>  
             
            <TabItem >  
                <Label Content="tab3"/>  
            </TabItem>  
        </TabControl>  
          
    </Grid>  

Or you can see if the solution here works for you.

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Answer 2

Hi,
try following demo. You can add TabItem via code or from XAML-file.

MainWindow

<Window x:Class="WpfApp1.Window019"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp019"
        mc:Ignorable="d"
        Title="Window019" Height="450" Width="800">
  <Window.DataContext>
    <local:ViewModel/>
  </Window.DataContext>
  <Grid>
    <TabControl ItemsSource="{Binding TabItems}"/>
  </Grid>
</Window>

ViewModel

using System.Collections.Generic;
using System.IO;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Markup;

namespace WpfApp019
{
  public class ViewModel
  {
    public ViewModel() => AddTabItems();

    public List<TabItem> TabItems { get; set; } = new List<TabItem>();

    private void AddTabItems()
    {
      TabItems.Add(new TabItem() { Header = "tab1", Content = new TextBlock() { Text = "Tab Data 1" } });
      using (Stream rdr = new FileStream("Window019TabItem.xaml", FileMode.Open)) TabItems.Add((TabItem)XamlReader.Load(rdr));
    }
  }
}

XAML TabItem

<TabItem xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         xmlns:local="clr-namespace:WpfApp1"
         mc:Ignorable="d" 
         d:DesignHeight="450" d:DesignWidth="800"
         Header="tab2"             >
  <Grid>
    <TextBlock Text="Tab Data 2" />
  </Grid>
</TabItem>