Exercise - Implement CRUD operations

  • 10 minutes

Let's continue extending our web API controller to add the ability to create (POST), update (PUT), and delete (DELETE) pizza from our inventory.

Add a pizza

Let's enable a pizza to be added through the web API by using a POST method.

Replace the // POST action comment in Controllers/PizzaController.cs with the following code:

[HttpPost]
public IActionResult Create(Pizza pizza)
{            
    PizzaService.Add(pizza);
    return CreatedAtAction(nameof(Get), new { id = pizza.Id }, pizza);
}

The preceding action:

  • Responds only to the HTTP POST verb, as denoted by the [HttpPost] attribute.
  • Inserts the request body's Pizza object into the in-memory cache.

Note

Because the controller is annotated with the [ApiController] attribute, it's implied that the Pizza parameter will be found in the request body.

The first parameter in the CreatedAtAction method call represents an action name. The nameof keyword is used to avoid hard-coding the action name. CreatedAtAction uses the action name to generate a location HTTP response header with a URL to the newly created pizza, as explained in the previous unit.

Modify a pizza

Now, let's enable a pizza to be updated through the web API by using a PUT method.

Replace the // PUT action comment in Controllers/PizzaController.cs with the following code:

[HttpPut("{id}")]
public IActionResult Update(int id, Pizza pizza)
{
    if (id != pizza.Id)
        return BadRequest();
           
    var existingPizza = PizzaService.Get(id);
    if(existingPizza is null)
        return NotFound();
   
    PizzaService.Update(pizza);           
   
    return NoContent();
}

The preceding action:

  • Responds only to the HTTP PUT verb, as denoted by the [HttpPut] attribute.
  • Requires that the id parameter's value is included in the URL segment after pizza/.
  • Returns IActionResult, because the ActionResult return type isn't known until runtime. The BadRequest, NotFound, and NoContent methods return BadRequestResult, NotFoundResult, and NoContentResult types, respectively.

Note

Because the controller is annotated with the [ApiController] attribute, it's implied that the Pizza parameter will be found in the request body.

Remove a pizza

Finally, let's enable a pizza to be removed through the web API by using a DELETE method.

Replace the // DELETE action comment in Controllers/PizzaController.cs with the following code:

[HttpDelete("{id}")]
public IActionResult Delete(int id)
{
    var pizza = PizzaService.Get(id);
   
    if (pizza is null)
        return NotFound();
       
    PizzaService.Delete(id);
   
    return NoContent();
}

The preceding action:

  • Responds only to the HTTP DELETE verb, as denoted by the [HttpDelete] attribute.
  • Requires that the id parameter's value is included in the URL segment after pizza/.
  • Returns IActionResult because the ActionResult return type isn't known until runtime. The NotFound and NoContent methods return NotFoundResult and NoContentResult types, respectively.
  • Queries the in-memory cache for a pizza that matches the provided id parameter.

Remember to save the Controllers/PizzaController.cs file before proceeding,

Build and run the finished web API

Build and start the web API by running the following command:

dotnet run

Test the finished web API with HTTP files

  1. Reopen the ContosoPizza.http file.

  2. Make a POST request to add a new pizza in HttpRepl by using the following command:

    POST {{ContosoPizza_HostAddress}}/pizza/
Content-Type: application/json

{
    "name": "Hawaii",
    "isGlutenFree": false
}

###

    The preceding command returns the newly created pizza:

    HTTP/1.1 201 Created
Connection: close
Content-Type: application/json; charset=utf-8
Date: Wed, 17 Jan 2024 17:03:02 GMT
Server: Kestrel
Location: http://localhost:5192/Pizza/3
Transfer-Encoding: chunked

{
    "id": 3,
    "name": "Hawaii",
    "isGlutenFree": false
}

  3. Update the new Hawaii pizza to a Hawaiian pizza with a PUT request by using the following command:

    PUT {{ContosoPizza_HostAddress}}/pizza/3
Content-Type: application/json

{
    "id": 3,
    "name": "Hawaiian",
    "isGlutenFree": false
}

###

    The preceding command returns the following output that indicates success:

    HTTP/1.1 204 No Content
Connection: close
Date: Wed, 17 Jan 2024 17:07:30 GMT
Server: Kestrel

    To verify that the pizza was updated, rerun the GET action by using the following command:

    GET {{ContosoPizza_HostAddress}}/pizza/3
Accept: application/json

###

    The preceding command returns the newly updated pizza:

    HTTP/1.1 200 OK
Connection: close
Content-Type: application/json; charset=utf-8
Date: Wed, 17 Jan 2024 17:09:01 GMT
Server: Kestrel
Transfer-Encoding: chunked

{
    "id": 3,
    "name": "Hawaiian",
    "isGlutenFree": false
}

  4. Our API can also delete the newly created pizza through the DELETE action if you run the following command:

    DELETE {{ContosoPizza_HostAddress}}/pizza/3

###

    The preceding command returns a 204 No Content result for success:

    HTTP/1.1 204 No Content
Date: Fri, 02 Apr 2021 23:30:04 GMT
Server: Kestrel

    To verify that the pizza was removed, rerun the GET action by using the following command:

    GET {{ContosoPizza_HostAddress}}/pizza/
Accept: application/json

###

    The preceding command returns the original pizzas as results:

    HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
Date: Fri, 02 Apr 2021 23:31:15 GMT
Server: Kestrel
Transfer-Encoding: chunked

[
    {
        "id": 1,
        "name": "Classic Italian",
        "isGlutenFree": false
    },
    {
        "id": 2,
        "name": "Veggie",
        "isGlutenFree": true
    }
]

You're now finished implementing and testing a newly created web API built with ASP.NET Core.

Optional: Test the finished web API with Command Line HTTPREPL

  1. Reopen the existing httprepl terminal, or open a new integrated terminal from Visual Studio Code by selecting Terminal > New Terminal from the main menu.

  2. If you opened a new terminal, connect to the web API by running the following command:

    httprepl https://localhost:{PORT}

    Alternatively, run the following command at any time while HttpRepl is running:

    connect https://localhost:{PORT}

  3. Go to the Pizza endpoint by running the following command:

    cd Pizza

  4. Run the following command to see the new actions on the Pizza API:

    ls

    The preceding command shows an output of available APIs for the Pizza endpoint:

        https://localhost:{PORT}/Pizza> ls
    .      [GET|POST]
    ..     []
    {id}   [GET|PUT|DELETE]

  5. Make a POST request to add a new pizza in HttpRepl by using the following command:

    post -c "{"name":"Hawaii", "isGlutenFree":false}"

    The preceding command returns the newly created pizza:

    HTTP/1.1 201 Created
Content-Type: application/json; charset=utf-8
Date: Fri, 02 Apr 2021 23:23:09 GMT
Location: https://localhost:{PORT}/Pizza?id=3
Server: Kestrel
Transfer-Encoding: chunked

{
    "id": 3,
    "name": "Hawaii",
    "isGlutenFree": false
}

  6. Update the new Hawaii pizza to a Hawaiian pizza with a PUT request by using the following command:

    put 3 -c  "{"id": 3, "name":"Hawaiian", "isGlutenFree":false}"

    The preceding command returns the following output that indicates success:

    HTTP/1.1 204 No Content
Date: Fri, 02 Apr 2021 23:23:55 GMT
Server: Kestrel

    To verify that the pizza was updated, rerun the GET action by using the following command:

    get 3

    The preceding command returns the newly updated pizza:

    HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
Date: Fri, 02 Apr 2021 23:27:37 GMT
Server: Kestrel
Transfer-Encoding: chunked

{
    "id": 3,
    "name": "Hawaiian",
    "isGlutenFree": false
}

  7. Our API can also delete the newly created pizza through the DELETE action if you run the following command:

    delete 3

    The preceding command returns a 204 No Content result for success:

    HTTP/1.1 204 No Content
Date: Fri, 02 Apr 2021 23:30:04 GMT
Server: Kestrel

    To verify that the pizza was removed, rerun the GET action by using the following command:

    get

    The preceding command returns the original pizzas as results:

    HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
Date: Fri, 02 Apr 2021 23:31:15 GMT
Server: Kestrel
Transfer-Encoding: chunked

[
    {
        "id": 1,
        "name": "Classic Italian",
        "isGlutenFree": false
    },
    {
        "id": 2,
        "name": "Veggie",
        "isGlutenFree": true
    }
]

You're now finished implementing and testing a newly created web API built with ASP.NET Core.