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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using Microsoft.Extensions.DependencyInjection;
namespace Microsoft.AspNetCore.Components;
/// <summary>
/// A base class that creates a service provider scope.
/// </summary>
/// <remarks>
/// Use the <see cref="OwningComponentBase"/> class as a base class to author components that control
/// the lifetime of a service provider scope. This is useful when using a transient or scoped service that
/// requires disposal such as a repository or database abstraction. Using <see cref="OwningComponentBase"/>
/// as a base class ensures that the service provider scope is disposed with the component.
/// </remarks>
public abstract class OwningComponentBase : ComponentBase, IDisposable, IAsyncDisposable
{
private AsyncServiceScope? _scope;
[Inject] IServiceScopeFactory ScopeFactory { get; set; } = default!;
/// <summary>
/// Gets a value determining if the component and associated services have been disposed.
/// </summary>
protected bool IsDisposed { get; private set; }
/// <summary>
/// Gets the scoped <see cref="IServiceProvider"/> that is associated with this component.
/// </summary>
protected IServiceProvider ScopedServices
{
get
{
if (ScopeFactory == null)
{
throw new InvalidOperationException("Services cannot be accessed before the component is initialized.");
}
ObjectDisposedException.ThrowIf(IsDisposed, this);
_scope ??= ScopeFactory.CreateAsyncScope();
return _scope.Value.ServiceProvider;
}
}
/// <inhertidoc />
void IDisposable.Dispose()
{
Dispose(disposing: true);
GC.SuppressFinalize(this);
}
/// <summary>
/// Releases the service scope used by the component.
/// </summary>
/// <param name="disposing">true to release both managed and unmanaged resources; false to release only unmanaged resources.</param>
protected virtual void Dispose(bool disposing)
{
if (!IsDisposed)
{
if (disposing && _scope.HasValue && _scope.Value is IDisposable disposable)
{
disposable.Dispose();
_scope = null;
}
IsDisposed = true;
}
}
/// <inhertidoc />
async ValueTask IAsyncDisposable.DisposeAsync()
{
await DisposeAsyncCore().ConfigureAwait(false);
Dispose(disposing: false);
GC.SuppressFinalize(this);
}
/// <summary>
/// Asynchronously releases the service scope used by the component.
/// </summary>
/// <returns>A task that represents the asynchronous dispose operation.</returns>
protected virtual async ValueTask DisposeAsyncCore()
{
if (!IsDisposed && _scope.HasValue)
{
await _scope.Value.DisposeAsync().ConfigureAwait(false);
_scope = null;
}
IsDisposed = true;
}
}
/// <summary>
/// A base class that creates a service provider scope, and resolves a service of type <typeparamref name="TService"/>.
/// </summary>
/// <typeparam name="TService">The service type.</typeparam>
/// <remarks>
/// Use the <see cref="OwningComponentBase{TService}"/> class as a base class to author components that control
/// the lifetime of a service or multiple services. This is useful when using a transient or scoped service that
/// requires disposal such as a repository or database abstraction. Using <see cref="OwningComponentBase{TService}"/>
/// as a base class ensures that the service and relates services that share its scope are disposed with the component.
/// </remarks>
public abstract class OwningComponentBase<TService> : OwningComponentBase, IDisposable where TService : notnull
{
private TService _item = default!;
/// <summary>
/// Gets the <typeparamref name="TService"/> that is associated with this component.
/// </summary>
protected TService Service
{
get
{
ObjectDisposedException.ThrowIf(IsDisposed, this);
// We cache this because we don't know the lifetime. We have to assume that it could be transient.
_item ??= ScopedServices.GetRequiredService<TService>();
return _item;
}
}
}
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