Prism loading dependent views
De Banane Atomic
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Description
When a view is injected into a region, trigger the load of other views in other regions and pass them the same DataContext.
Region behavior and Attribute
| DependentViewRegionBehavior.cs |
public class DependentViewRegionBehavior : RegionBehavior
{
private readonly Dictionary<object, List<DependentViewInfo>> _dependentViewCache = new Dictionary<object, List<DependentViewInfo>>();
protected override void OnAttach()
{
Region.ActiveViews.CollectionChanged += ActiveViewsOnCollectionChanged;
}
private void ActiveViewsOnCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
if (e.Action == NotifyCollectionChangedAction.Add)
{
foreach (var view in e.NewItems)
{
if (!_dependentViewCache.TryGetValue(view, out var viewInfoList))
{
viewInfoList = new List<DependentViewInfo>();
foreach (var attribute in GetCustomAttribute<DependentViewAttribute>(view.GetType()))
{
var viewInfo = CreateDependentView(attribute);
if (viewInfo.View is FrameworkElement viewToInject &&
view is FrameworkElement viewTrigger)
{
viewToInject.DataContext = viewTrigger.DataContext;
}
viewInfoList.Add(viewInfo);
}
if (!_dependentViewCache.ContainsKey(view))
{
_dependentViewCache.Add(view, viewInfoList);
}
}
viewInfoList.ForEach(x => Region.RegionManager.Regions[x.TargetRegionName].Add(x.View));
}
}
if (e.Action == NotifyCollectionChangedAction.Remove)
{
foreach (var view in e.OldItems)
{
if (_dependentViewCache.TryGetValue(view, out var viewInfoList))
{
viewInfoList.ForEach(x => Region.RegionManager.Regions[x.TargetRegionName].Remove(x.View));
}
}
}
}
private DependentViewInfo CreateDependentView(DependentViewAttribute attribute)
{
return new DependentViewInfo
{
View = attribute.Type != null ? Activator.CreateInstance(attribute.Type) : null,
TargetRegionName = attribute.TargetRegionName
};
}
private static IEnumerable<T> GetCustomAttribute<T>(Type type) => type.GetCustomAttributes(typeof(T), true).OfType<T>();
}
internal class DependentViewInfo
{
public object View { get; set; }
public string TargetRegionName { get; set; }
}
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