How Dependency Injection Containers Work in C#?

Dependency Injection (DI) containers, such as Unity or DryIoc, help manage the creation and lifetime of object dependencies in C#. They facilitate the Inversion of Control (IoC) principle, allowing you to focus on writing clean, maintainable code without worrying about the complexities of instantiating dependencies manually. How DI Containers Work? Registration:  You define which concrete classes should be used to fulfill specific interface contracts. This allows the DI container to know what to instantiate when a class requests a particular dependency. Resolution:  When an instance of a class is requested, the DI container looks at the registered services, resolves the dependencies, and creates the object with the required dependencies injected. Lifetime Management:  The container manages the lifecycle of the dependencies. You can specify whether instances should be singleton (one instance for the entire application), transient (a new instance each time), or scoped (one ...

Dynamically Creating a TabControl using Prism Region in WPF: A Step-by-Step Guide

In this post, we'll demonstrate how to use Prism Regions to create a dynamic TabControl in WPF, where each tab is loaded with a separate view.

Step 1: Create a new Prism WPF project

To get started, create a new Prism WPF project using the Prism Template Pack.
Open Visual Studio and select "Create a new project". 
In the "New Project" dialog, select "Prism WPF App" under the "Prism" category.

Step 2: Add a TabControl to your main view

In the main view of your application, add a TabControl to the XAML markup. Set its ItemsSource property to a collection of objects that represent each tab item. In this example, we'll use an ObservableCollection<TabItem> property defined in the view model.

<TabControl ItemsSource="{Binding TabItems}">
  <TabControl.ItemTemplate>
    <DataTemplate>
      <TextBlock Text="{Binding Header}" />
    </DataTemplate>
  </TabControl.ItemTemplate>
  <TabControl.ContentTemplate>
    <DataTemplate>
      <ContentControl prism:RegionManager.RegionName="{Binding RegionName}" />
    </DataTemplate>
  </TabControl.ContentTemplate>
</TabControl>


Notice that we're using a ContentControl to load the content of each tab. This is because we want to use Prism Regions to dynamically load and unload views in each tab.

We're also using a DataTemplate for the tab headers, which binds to the Header property of the TabItem object.



Step 3: Define the TabItem objects in your view model

In your view model, define a collection of TabItem objects that correspond to each tab. Each TabItem should have a unique RegionName property that corresponds to the name of the Prism Region that will be loaded in the tab.


public class MainViewModel
{
  public ObservableCollection<TabItem> TabItems { get; set; }
  
  public MainViewModel()
  {
    TabItems = new ObservableCollection<TabItem>();
    TabItems.Add(new TabItem { Header = "Tab 1", RegionName = "Tab1Region" });
    TabItems.Add(new TabItem { Header = "Tab 2", RegionName = "Tab2Region" });
  }
}

public class TabItem
{
  public string Header { get; set; }
  public string RegionName { get; set; }
}


We'll bind the TabControl's ItemsSource property to this collection in the XAML markup.



Step 4: Register the regions in your Prism Bootstrapper

In your Prism Bootstrapper, register the regions that will be loaded in the tabs. We'll use a ContentControlRegionAdapter class to adapt the ContentControl to a Prism Region.

protected override void ConfigureRegionAdapterMappings(RegionAdapterMappings mappings)
{
  base.ConfigureRegionAdapterMappings(mappings);
  mappings.RegisterMapping(typeof(ContentControl), Container.Resolve<ContentControlRegionAdapter>());
}

The ConfigureRegionAdapterMappings method is called when the Prism application is initialized. Here, we're registering a new mapping for the ContentControl type, using an instance of our custom ContentControlRegionAdapter.

Step 5: Create a custom RegionAdapter for the ContentControl

Finally, we need to create our custom ContentControlRegionAdapter class. 

public class ContentControlRegionAdapter : RegionAdapterBase<ContentControl>
{
  public ContentControlRegionAdapter(IRegionBehaviorFactory regionBehaviorFactory) : base(regionBehaviorFactory)
  {
  }

  protected override void Adapt(IRegion region, ContentControl regionTarget)
  {
    region.Views.CollectionChanged += (s, e) =>
    {
      if (e.Action == NotifyCollectionChangedAction.Add)
      {
        foreach (object view in e.NewItems)
        {
          regionTarget.Content = view;
        }
      }
    };
  }

  protected override IRegion CreateRegion()
  {
    return new SingleActiveRegion();
  }
}

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