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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 System.Diagnostics;
using System.Diagnostics.Metrics;
using Microsoft.AspNetCore.Diagnostics;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
namespace Microsoft.AspNetCore.Builder;
/// <summary>
/// Extension methods for enabling <see cref="ExceptionHandlerExtensions"/>.
/// </summary>
public static class ExceptionHandlerExtensions
{
/// <summary>
/// Adds a middleware to the pipeline that will catch exceptions, log them, and re-execute the request in an alternate pipeline.
/// The request will not be re-executed if the response has already started.
/// </summary>
/// <param name="app"></param>
/// <returns></returns>
public static IApplicationBuilder UseExceptionHandler(this IApplicationBuilder app)
{
ArgumentNullException.ThrowIfNull(app);
return SetExceptionHandlerMiddleware(app, options: null);
}
/// <summary>
/// Adds a middleware to the pipeline that will catch exceptions, log them, reset the request path, and re-execute the request.
/// The request will not be re-executed if the response has already started.
/// </summary>
/// <param name="app"></param>
/// <param name="errorHandlingPath"></param>
/// <returns></returns>
public static IApplicationBuilder UseExceptionHandler(this IApplicationBuilder app, string errorHandlingPath)
{
ArgumentNullException.ThrowIfNull(app);
return app.UseExceptionHandler(new ExceptionHandlerOptions
{
ExceptionHandlingPath = new PathString(errorHandlingPath)
});
}
/// <summary>
/// Adds a middleware to the pipeline that will catch exceptions, log them, reset the request path, and re-execute the request.
/// The request will not be re-executed if the response has already started.
/// </summary>
/// <param name="app">The <see cref="IApplicationBuilder"/>.</param>
/// <param name="errorHandlingPath">The <see cref="string"/> path to the endpoint that will handle the exception.</param>
/// <param name="createScopeForErrors">Whether or not to create a new <see cref="IServiceProvider"/> scope.</param>
/// <returns></returns>
public static IApplicationBuilder UseExceptionHandler(this IApplicationBuilder app, string errorHandlingPath, bool createScopeForErrors)
{
ArgumentNullException.ThrowIfNull(app);
return app.UseExceptionHandler(new ExceptionHandlerOptions
{
ExceptionHandlingPath = new PathString(errorHandlingPath),
CreateScopeForErrors = createScopeForErrors
});
}
/// <summary>
/// Adds a middleware to the pipeline that will catch exceptions, log them, and re-execute the request in an alternate pipeline.
/// The request will not be re-executed if the response has already started.
/// </summary>
/// <param name="app"></param>
/// <param name="configure"></param>
/// <returns></returns>
public static IApplicationBuilder UseExceptionHandler(this IApplicationBuilder app, Action<IApplicationBuilder> configure)
{
ArgumentNullException.ThrowIfNull(app);
ArgumentNullException.ThrowIfNull(configure);
var subAppBuilder = app.New();
configure(subAppBuilder);
var exceptionHandlerPipeline = subAppBuilder.Build();
return app.UseExceptionHandler(new ExceptionHandlerOptions
{
ExceptionHandler = exceptionHandlerPipeline
});
}
/// <summary>
/// Adds a middleware to the pipeline that will catch exceptions, log them, and re-execute the request in an alternate pipeline.
/// The request will not be re-executed if the response has already started.
/// </summary>
/// <param name="app"></param>
/// <param name="options"></param>
/// <returns></returns>
public static IApplicationBuilder UseExceptionHandler(this IApplicationBuilder app, ExceptionHandlerOptions options)
{
ArgumentNullException.ThrowIfNull(app);
ArgumentNullException.ThrowIfNull(options);
var iOptions = Options.Create(options);
return SetExceptionHandlerMiddleware(app, iOptions);
}
private static IApplicationBuilder SetExceptionHandlerMiddleware(IApplicationBuilder app, IOptions<ExceptionHandlerOptions>? options)
{
var problemDetailsService = app.ApplicationServices.GetService<IProblemDetailsService>();
app.Properties["analysis.NextMiddlewareName"] = "Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware";
// Only use this path if there's a global router (in the 'WebApplication' case).
if (app.Properties.TryGetValue(RerouteHelper.GlobalRouteBuilderKey, out var routeBuilder) && routeBuilder is not null)
{
return app.Use(next =>
{
var loggerFactory = app.ApplicationServices.GetRequiredService<ILoggerFactory>();
var diagnosticListener = app.ApplicationServices.GetRequiredService<DiagnosticListener>();
var exceptionHandlers = app.ApplicationServices.GetRequiredService<IEnumerable<IExceptionHandler>>();
var meterFactory = app.ApplicationServices.GetRequiredService<IMeterFactory>();
if (options is null)
{
options = app.ApplicationServices.GetRequiredService<IOptions<ExceptionHandlerOptions>>();
}
if (!string.IsNullOrEmpty(options.Value.ExceptionHandlingPath) && options.Value.ExceptionHandler is null)
{
var newNext = RerouteHelper.Reroute(app, routeBuilder, next);
// store the pipeline for the error case
options.Value.ExceptionHandler = newNext;
}
return new ExceptionHandlerMiddlewareImpl(next, loggerFactory, options, diagnosticListener, exceptionHandlers, meterFactory, problemDetailsService).Invoke;
});
}
if (options is null)
{
return app.UseMiddleware<ExceptionHandlerMiddlewareImpl>();
}
return app.UseMiddleware<ExceptionHandlerMiddlewareImpl>(options);
}
}
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