80 lines
3.3 KiB
C#
80 lines
3.3 KiB
C#
using System;
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using System.Diagnostics;
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using System.Reflection;
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using System.Threading.Tasks;
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using Tapeti.Annotations;
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using Tapeti.Config;
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using Tapeti.Helpers;
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namespace Tapeti.Default
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{
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/// <inheritdoc />
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/// <summary>
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/// Attempts to publish a return value for Controller methods as a response to the incoming message.
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/// </summary>
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public class PublishResultBinding : IControllerBindingMiddleware
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{
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/// <inheritdoc />
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public void Handle(IControllerBindingContext context, Action next)
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{
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next();
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if (context.Result.HasHandler)
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return;
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var hasClassResult = context.Result.Info.ParameterType.IsTypeOrTaskOf(t => t.IsClass, out var isTaskOf, out var actualType);
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var request = context.MessageClass?.GetCustomAttribute<RequestAttribute>();
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var expectedClassResult = request?.Response;
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// Verify the return type matches with the Request attribute of the message class. This is a backwards incompatible change in
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// Tapeti 1.2: if you just want to publish another message as a result of the incoming message, explicitly call IPublisher.Publish.
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// ReSharper disable once ConvertIfStatementToSwitchStatement
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if (!hasClassResult && expectedClassResult != null || hasClassResult && expectedClassResult != actualType)
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throw new ArgumentException($"Message handler must return type {expectedClassResult?.FullName ?? "void"} in controller {context.Method.DeclaringType?.FullName}, method {context.Method.Name}, found: {actualType?.FullName ?? "void"}");
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if (!hasClassResult)
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return;
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if (isTaskOf)
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{
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var handler = GetType().GetMethod("PublishGenericTaskResult", BindingFlags.NonPublic | BindingFlags.Static)?.MakeGenericMethod(actualType);
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Debug.Assert(handler != null, nameof(handler) + " != null");
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context.Result.SetHandler(async (messageContext, value) => { await (Task) handler.Invoke(null, new[] {messageContext, value }); });
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}
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else
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context.Result.SetHandler((messageContext, value) => Reply(value, messageContext));
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}
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// ReSharper disable once UnusedMember.Local - used implicitly above
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private static async Task PublishGenericTaskResult<T>(IMessageContext messageContext, object value) where T : class
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{
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var message = await (Task<T>)value;
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await Reply(message, messageContext);
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}
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private static Task Reply(object message, IMessageContext messageContext)
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{
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if (message == null)
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throw new ArgumentException("Return value of a request message handler must not be null");
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var publisher = (IInternalPublisher)messageContext.Config.DependencyResolver.Resolve<IPublisher>();
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var properties = new MessageProperties
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{
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CorrelationId = messageContext.Properties.CorrelationId
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};
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return !string.IsNullOrEmpty(messageContext.Properties.ReplyTo)
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? publisher.PublishDirect(message, messageContext.Properties.ReplyTo, properties, messageContext.Properties.Persistent.GetValueOrDefault(true))
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: publisher.Publish(message, properties, false);
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}
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}
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}
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