44 lines
1.3 KiB
Markdown
44 lines
1.3 KiB
Markdown
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---
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title: "ASP0016: Do not return a value from RequestDelegate"
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description: "Learn about analysis rule ASP0016: Do not return a value from RequestDelegate"
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author: tdykstra
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monikerRange: '>= aspnetcore-8.0'
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ms.author: tdykstra
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ms.date: 11/22/2022
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uid: diagnostics/asp0016
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---
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# ASP0016: Do not return a value from RequestDelegate
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| | Value |
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| **Rule ID** |ASP0016|
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| **Category** |Usage|
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| **Fix is breaking or non-breaking** |Non-breaking|
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## Cause
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A method used to create a <xref:Microsoft.AspNetCore.Http.RequestDelegate> returns `Task<T>`. `RequestDelegate` discards this value.
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## Rule description
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Do not return a value `Delegate`s provided to APIs that expect `RequestDelegate`. For example, the following sample returns a `Task<string>` where the `string` value of the `Task` will be discarded.
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```csharp
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var app = WebApplication.Create();
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app.Use(next =>
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{
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return new RequestDelegate((HttpContext context) =>
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{
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return Task.FromResult(""hello world"");
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});
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});
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```
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## How to fix violations
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To fix a violation of this rule, change the return type to non-generic `Task` or, if the delegate is a route handler, cast it to `Delegate` so the return value is written to the response.
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## When to suppress warnings
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Do not suppress a warning from this rule.
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