Introduced v15 changes w.r.t. providers

README.md

@@ -544,6 +544,26 @@ To dynamically change / refresh your components when the language change you'll
 
 This way, your components will always remain up-to-date and render the right translations.
 
+## Provider Components
+
+Sometimes Blazor components require some global components (or "providers") to be added. To accomplish this you can create components marked with the `PiralProviderAttribute` attribute.
+
+Example:
+
+
+```razor
+@attribute [PiralProvider]
+<MudThemeProvider/>
+<MudDialogProvider/>
+<MudSnackbarProvider/>
+```
+
+Providers will *never* receive any parameters - they are rendered only once and will remain active for the whole lifecycle of the application. There can be more than one provider.
+
+Provider components are adjacent to your other components, which may come and go and will be - in general - somewhere else in the DOM. As such they are not ideal for providing some cascading value or other properties. They are ideal, however, when you need something running all the time.
+
+In contrast, Piral also has the concept of a root component, which comes with another set of constraints.
+
 ### Root Component
 
 By default, the Blazor pilets run in a dedicated Blazor application with no root component. If you need a root component, e.g., to provide some common values from a `CascadingValue` component such as `CascadingAuthenticationState` from the `Microsoft.AspNetCore.Components.Authorization` package, you can actually override the default root component:
@@ -582,7 +602,7 @@ You can also provide your own providers here (or nest them as you want):
 
 **Note**: There is always just one `PiralAppRoot` component. If you did not supply one then the default `PiralAppRoot` will be used. If you already provided one, no other `PiralAppRoot` can be used.
 
-It is critical to understand that each attached pilet component starts its own Blazor rendering tree. Therefore, while there is just a single `PiralAppRoot` component there might be multiple instances active at a given point in time.
+It is critical to understand that each attached pilet component starts its own Blazor rendering tree. Therefore, while there is just a single `PiralAppRoot` component there might be multiple instances active at a given point in time. This is a crucial difference to `PiralProvider` components, which are essentially singletons from a rendering perspective.
 
 ## Running and Debugging the Pilet :rocket:
 

src/Piral.Blazor.Core/App.razor

@@ -1,6 +1,7 @@
 @inject IComponentActivationService Activation
 @implements IDisposable
 
+<PiralProviders />
 <RenderView Type="@Activation.Root" Parameters="@parameters" />
 
 @code {

src/Piral.Blazor.Core/ComponentActivationService.cs

@@ -11,31 +11,38 @@ namespace Piral.Blazor.Core;
 
 public class ComponentActivationService : IComponentActivationService
 {
-    private static readonly string appRoot = "approot";
+    private static readonly string appRoot = "#approot";
 
     private readonly Dictionary<string, Type> _components = new();
 
     private readonly Dictionary<string, PiralElement> _elements = new();
 
     private readonly List<ActiveComponent> _active = new();
 
+    private readonly List<Type> _provider = new();
+
     private readonly ILogger<ComponentActivationService> _logger;
 
     private readonly IModuleContainerService _container;
-    
+
     private readonly NavigationManager _navigationManager;
 
     public event EventHandler ComponentsChanged;
 
+    public event EventHandler ProvidersChanged;
+
     public event EventHandler RootChanged;
 
     public IEnumerable<ActiveComponent> Components => _active;
 
+    public IEnumerable<Type> Providers => _provider;
+
     public Type Root => GetComponent(appRoot) ?? typeof(DefaultRoot);
 
     private static readonly IReadOnlyCollection<Type> AttributeTypes = new List<Type>
     {
         typeof(PiralAppRootAttribute),
+        typeof(PiralProviderAttribute),
         typeof(PiralComponentAttribute),
         typeof(PiralExtensionAttribute),
         typeof(RouteAttribute),
@@ -55,6 +62,11 @@ public void Register(string componentName, Type componentType)
         {
             _logger.LogWarning("The provided component name has already been registered.");
         }
+        else if (componentName.StartsWith("provider-"))
+        {
+            _provider.Add(componentType);
+            ProvidersChanged?.Invoke(this, EventArgs.Empty);
+        }
         else
         {
             _components.Add(componentName, componentType);
@@ -70,12 +82,21 @@ public void Unregister(string componentName)
     {
         if (_components.TryGetValue(componentName, out var componentType))
         {
-            DeactivateComponent(componentName);
-            _components.Remove(componentName);
-
-            if (componentName == appRoot)
+            if (componentName.StartsWith("provider-"))
             {
                 RootChanged?.Invoke(this, EventArgs.Empty);
+                _provider.Remove(componentType);
+                ProvidersChanged?.Invoke(this, EventArgs.Empty);
+            }
+            else
+            {
+                DeactivateComponent(componentName);
+                _components.Remove(componentName);
+
+                if (componentName == appRoot)
+                {
+                    RootChanged?.Invoke(this, EventArgs.Empty);
+                }
             }
         }
         else
@@ -303,6 +324,8 @@ private static IEnumerable<string> GetComponentNameToRegister(Type member, Type
                     $"{((PiralComponentAttribute)attribute).Name ?? member.FullName}",
                 Type _ when attributeType == typeof(PiralAppRootAttribute) =>
                     appRoot,
+                Type _ when attributeType == typeof(PiralProviderAttribute) =>
+                    $"provider-{member.FullName}",
                 _ => null
             });
         }

src/Piral.Blazor.Core/ComponentView.razor

@@ -3,7 +3,7 @@
 
 @foreach (var active in Activation.Components)
 {
-    <div id="@active.ReferenceId">
+    <div id="@active.ReferenceId" style="display: none">
         <div style="display: contents">
             <RenderView Type="@active.Component" Parameters="@active.Args" />
         </div>

src/Piral.Blazor.Core/IComponentActivationService.cs

@@ -9,6 +9,11 @@ public interface IComponentActivationService
     /// The handler to monitor when the active components changed.
     /// </summary>
     event EventHandler ComponentsChanged;
+
+    /// <summary>
+    /// The handler to monitor when the available providers changed.
+    /// </summary>
+    event EventHandler ProvidersChanged;
 
     /// <summary>
     /// The handler to monitor when the root component changed.
@@ -20,6 +25,11 @@ public interface IComponentActivationService
     /// </summary>
     IEnumerable<ActiveComponent> Components { get; }
 
+    /// <summary>
+    /// Gets the currently available providers.
+    /// </summary>
+    IEnumerable<Type> Providers { get; }
+
     /// <summary>
     /// Gets a mounted element using its reference ID.
     /// </summary>
@@ -29,4 +39,4 @@ public interface IComponentActivationService
     /// Gets the configured root component.
     /// </summary>
     Type Root { get; }
-}
+}

src/Piral.Blazor.Core/PiralProviders.razor

@@ -0,0 +1,25 @@
+@inject IComponentActivationService Activation
+@implements IDisposable
+
+@foreach (var provider in Activation.Providers)
+{
+    <DynamicComponent Type="@provider" />
+}
+
+@code {
+private void ProvidersChanged(object sender, EventArgs e)
+{
+    this.StateHasChanged();
+}
+
+public void Dispose()
+{
+    Activation.ProvidersChanged -= ProvidersChanged;
+}
+
+protected override Task OnInitializedAsync()
+{
+    Activation.ProvidersChanged += ProvidersChanged;
+    return base.OnInitializedAsync();
+}
+}

src/Piral.Blazor.Utils/PiralProviderAttribute.cs

@@ -0,0 +1,12 @@
+using System;
+
+namespace Piral.Blazor.Utils;
+
+[AttributeUsage(AttributeTargets.Class, Inherited = true)]
+public class PiralProviderAttribute : Attribute
+{
+    /// <summary>
+    /// Registers a Piral provider component.
+    /// </summary>
+    public PiralProviderAttribute() { }
+}