AspNetCore.Docs/aspnetcore/tutorials/first-web-api-mac.md

title	author	description	ms.author	ms.custom	ms.date	uid
Create a Web API with ASP.NET Core and Visual Studio for Mac	rick-anderson	Create a Web API with ASP.NET Core MVC and Visual Studio for Mac	riande	mvc	05/08/2018	tutorials/first-web-api-mac

Create a Web API with ASP.NET Core and Visual Studio for Mac

By Rick Anderson and Mike Wasson

In this tutorial, build a web API for managing a list of "to-do" items. The UI isn't constructed.

There are three versions of this tutorial:

• macOS: Web API with Visual Studio for Mac (This tutorial)
• Windows: Web API with Visual Studio for Windows
• macOS, Linux, Windows: Web API with Visual Studio Code

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See Introduction to ASP.NET Core MVC on macOS or Linux for an example that uses a persistent database.

Prerequisites

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Create the project

From Visual Studio, select File > New Solution.

Select .NET Core App > ASP.NET Core Web API > Next.

Enter TodoApi for the Project Name, and then click Create.

Launch the app

In Visual Studio, select Run > Start With Debugging to launch the app. Visual Studio launches a browser and navigates to http://localhost:5000. You get an HTTP 404 (Not Found) error. Change the URL to http://localhost:<port>/api/values. The ValuesController data is displayed:

["value1","value2"]

Add support for Entity Framework Core

Install the Entity Framework Core InMemory database provider. This database provider allows Entity Framework Core to be used with an in-memory database.

• From the Project menu, select Add NuGet Packages.

  • Alternatively, you can right-click Dependencies, and then select Add Packages.

• Enter EntityFrameworkCore.InMemory in the search box.

• Select Microsoft.EntityFrameworkCore.InMemory, and then select Add Package.

Add a model class

A model is an object representing the data in your app. In this case, the only model is a to-do item.

In Solution Explorer, right-click the project. Select Add > New Folder. Name the folder Models.

[!NOTE] You can put model classes anywhere in your project, but the Models folder is used by convention.

Right-click the Models folder, and select Add > New File > General > Empty Class. Name the class TodoItem, and then click New.

Replace the generated code with:

[!code-csharp]

The database generates the Id when a TodoItem is created.

Create the database context

The database context is the main class that coordinates Entity Framework functionality for a given data model. You create this class by deriving from the Microsoft.EntityFrameworkCore.DbContext class.

Add a TodoContext class to the Models folder.

[!code-csharp]

[!INCLUDERegister the database context]

Add a controller

In Solution Explorer, in the Controllers folder, add the class TodoController.

Replace the generated code with the following:

[!INCLUDEcode and get todo items]

Launch the app

In Visual Studio, select Run > Start With Debugging to launch the app. Visual Studio launches a browser and navigates to http://localhost:<port>, where <port> is a randomly chosen port number. You get an HTTP 404 (Not Found) error. Change the URL to http://localhost:<port>/api/values. The ValuesController data is displayed:

["value1","value2"]

Navigate to the Todo controller at http://localhost:<port>/api/todo. The following JSON is returned:

[{"key":1,"name":"Item1","isComplete":false}]

Implement the other CRUD operations

We'll add Create, Update, and Delete methods to the controller. These methods are variations on a theme, so I'll just show the code and highlight the main differences. Build the project after adding or changing code.

Create

::: moniker range="<= aspnetcore-2.0"

[!code-csharp]

The preceding method responds to an HTTP POST, as indicated by the [HttpPost] attribute. The [FromBody] attribute tells MVC to get the value of the to-do item from the body of the HTTP request.

::: moniker-end

::: moniker range=">= aspnetcore-2.1"

[!code-csharp]

The preceding method responds to an HTTP POST, as indicated by the [HttpPost] attribute. MVC gets the value of the to-do item from the body of the HTTP request.

::: moniker-end

The CreatedAtRoute method returns a 201 response. It's the standard response for an HTTP POST method that creates a new resource on the server. CreatedAtRoute also adds a Location header to the response. The Location header specifies the URI of the newly created to-do item. See 10.2.2 201 Created.

Use Postman to send a Create request

• Start the app (Run > Start With Debugging).
• Open Postman.

• Update the port number in the localhost URL.
• Set the HTTP method to POST.
• Click the Body tab.
• Select the raw radio button.
• Set the type to JSON (application/json).
• Enter a request body with a to-do item resembling the following JSON:

{
  "name":"walk dog",
  "isComplete":true
}

• Click the Send button.

::: moniker range=">= aspnetcore-2.1"

[!TIP] If no response displays after clicking Send, disable the SSL certification verification option. This is found under File > Settings. Click the Send button again after disabling the setting.

::: moniker-end

Click the Headers tab in the Response pane and copy the Location header value:

You can use the Location header URI to access the resource you created. The Create method returns CreatedAtRoute. The first parameter passed to CreatedAtRoute represents the named route to use for generating the URL. Recall that the GetById method created the "GetTodo" named route:

[HttpGet("{id}", Name = "GetTodo")]

Update

::: moniker range="<= aspnetcore-2.0"

[!code-csharp]

::: moniker-end

::: moniker range=">= aspnetcore-2.1"

[!code-csharp]

::: moniker-end

Update is similar to Create, but uses HTTP PUT. The response is 204 (No Content). According to the HTTP spec, a PUT request requires the client to send the entire updated entity, not just the deltas. To support partial updates, use HTTP PATCH.

{
  "key": 1,
  "name": "walk dog",
  "isComplete": true
}

Delete

[!code-csharp]

The response is 204 (No Content).

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