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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 will be displayed:
Install the [Entity Framework Core InMemory](https://docs.microsoft.com/ef/core/providers/in-memory/) database provider. This database provider allows Entity Framework Core to be used with an in-memory database.
Note: You can put model classes anywhere in your project, but the *Models* folder is used by convention.
Add a `TodoItem` class. Right-click the *Models* folder and select **Add > New File > General > Empty Class**. Name the class `TodoItem`, and then select **New**.
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.
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 will be displayed:
```
["value1","value2"]
```
Navigate to the `Todo` controller at`http://localhost:port/api/todo`:
```
[{"key":1,"name":"Item1","isComplete":false}]
```
## Implement the other CRUD operations
We'll add `Create`, `Update`, and `Delete` methods to the controller. These 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.
This is an HTTP POST method, indicated by the [`[HttpPost]`](/aspnet/core/api/microsoft.aspnetcore.mvc.httppostattribute) attribute. The [`[FromBody]`](/aspnet/core/api/microsoft.aspnetcore.mvc.frombodyattribute) attribute tells MVC to get the value of the to-do item from the body of the HTTP request.
The `CreatedAtRoute` method returns a 201 response, which is 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](http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html).
### Use Postman to send a Create request
* Start the app (**Run > Start With Debugging**).
* Start Postman.
* Set the HTTP method to `POST`
* Select the **Body** radio button
* Select the **raw** radio button
* Set the type to JSON
* In the key-value editor, enter a Todo item such as
```json
{
"name":"walk dog",
"isComplete":true
}
```
* Select **Send**
* Select the Headers tab in the lower pane and copy the **Location** header:
You can use the Location header URI to access the resource you just created. Recall the `GetById` method created the `"GetTodo"` named route:
`Update` is similar to `Create`, but uses HTTP PUT. The response is [204 (No Content)](http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html). 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.
```json
{
"key": 1,
"name": "walk dog",
"isComplete": true
}
```
* [View or download sample code](https://github.com/aspnet/Docs/tree/master/aspnetcore/tutorials/first-web-api/sample) ([how to download](xref:tutorials/index#how-to-download-a-sample))
