AspNetCore.Docs/aspnetcore/web-api/advanced/analyzers.md

---
title: Use web API analyzers
author: pranavkm
description: Learn about the web API analyzers in Microsoft.AspNetCore.Mvc.Api.Analyzers.
monikerRange: '>= aspnetcore-2.2'
ms.author: pranavkm
ms.custom: mvc
ms.date: 12/14/2018
uid: web-api/advanced/analyzers
---
# Use web API analyzers

ASP.NET Core 2.2 and later includes the [Microsoft.AspNetCore.Mvc.Api.Analyzers](https://www.nuget.org/packages/Microsoft.AspNetCore.Mvc.Api.Analyzers) NuGet package containing analyzers for web APIs. The analyzers work with controllers annotated with <xref:Microsoft.AspNetCore.Mvc.ApiControllerAttribute>, while building on [API conventions](xref:web-api/advanced/conventions).

## Package installation

`Microsoft.AspNetCore.Mvc.Api.Analyzers` can be added with one of the following approaches:

### [Visual Studio](#tab/visual-studio)

* From the **Package Manager Console** window:
  * Go to **View** > **Other Windows** > **Package Manager Console**.
  * Navigate to the directory in which the *ApiConventions.csproj* file exists.
  * Execute the following command:

    ```powershell
    Install-Package Microsoft.AspNetCore.Mvc.Api.Analyzers
    ```

* From the **Manage NuGet Packages** dialog:
  * Right-click the project in **Solution Explorer** > **Manage NuGet Packages**.
  * Set the **Package source** to "nuget.org".
  * Enter "Microsoft.AspNetCore.Mvc.Api.Analyzers" in the search box.
  * Select the "Microsoft.AspNetCore.Mvc.Api.Analyzers" package from the **Browse** tab and click **Install**.

### [Visual Studio for Mac](#tab/visual-studio-mac)

* Right-click the *Packages* folder in **Solution Pad** > **Add Packages...**.
* Set the **Add Packages** window's **Source** drop-down to "nuget.org".
* Enter "Microsoft.AspNetCore.Mvc.Api.Analyzers" in the search box.
* Select the "Microsoft.AspNetCore.Mvc.Api.Analyzers" package from the results pane and click **Add Package**.

### [Visual Studio Code](#tab/visual-studio-code)

Run the following command from the **Integrated Terminal**:

```console
dotnet add ApiConventions.csproj package Microsoft.AspNetCore.Mvc.Api.Analyzers
```

### [.NET Core CLI](#tab/netcore-cli)

Run the following command:

```console
dotnet add ApiConventions.csproj package Microsoft.AspNetCore.Mvc.Api.Analyzers
```

---

## Analyzers for API conventions

OpenAPI documents contain status codes and response types that an action may return. In ASP.NET Core MVC, attributes such as <xref:Microsoft.AspNetCore.Mvc.ProducesResponseTypeAttribute> and <xref:Microsoft.AspNetCore.Mvc.ProducesAttribute> are used to document an action. <xref:tutorials/web-api-help-pages-using-swagger> goes into further detail on documenting your API.

One of the analyzers in the package inspects controllers annotated with <xref:Microsoft.AspNetCore.Mvc.ApiControllerAttribute> and identifies actions that don't entirely document their responses. Consider the following example:

[!code-csharp[](conventions/sample/Controllers/ContactsController.cs?name=missing404docs&highlight=9)]

The preceding action documents the HTTP 200 success return type but doesn't document the HTTP 404 failure status code. The analyzer reports the missing documentation for the HTTP 404 status code as a warning. An option to fix the problem is provided.

## Additional resources

* <xref:web-api/advanced/conventions>
* <xref:tutorials/web-api-help-pages-using-swagger>
* [Annotation with ApiController attribute](xref:web-api/index#annotation-with-apicontroller-attribute)