Which Keywords are Valid for CRUD Calls in ASP.NET Core?

I am going through the tutorial found at https://learn.microsoft.com/en-gb/training/modules/build-web-api-aspnet-core/7-crud.

One of the paragraphs state

> The [HttpPost] attribute will map HTTP POST requests sent to http://localhost:5000/pizza by using the Create() method.

Now i read somewhere that using the Get, Post, Delete as the name in the Controller Action would automatically map that keyword to the appropriate action (I may have confused myself on this so maybe a little clarity in case im getting mixed up with Entity Framework) for example

• public IActionResult Get() .. would get the records
• public IActionResult Post(Pizza pizza) .. would post a record (insert into the DB)

But i dont see anywhere in the documentation to support the Create method so im confused how this code

[HttpPost]
public IActionResult Create(Pizza pizza)
{            
    // This code will save the pizza and return a result
}

would create a new pizza when it calls http://localhost:5000/pizza? How does /pizza map to Create?

I am going through the tutorial found at https://learn.microsoft.com/en-gb/training/modules/build-web-api-aspnet-core/7-crud

Also viewed the help file at https://learn.microsoft.com/en-us/aspnet/core/mvc/controllers/routing?view=aspnetcore-7.0 which didnt answer my question.

This is the workflow explaining the map of Action() in the controller.

1. Searches for verb name in the controller. For example: a GET HTTP
   request looks for a Get() action defined in the controller. If it
   exists executes otherwise the following happens.
2. Searches for an action starting with Get. For example if Get() does
   not exist in the controller then it looks for an action that starts
   with GetWHATEVERNAME() for example GetData(). If there is no action
   that starts with even Get(). If it exists executes otherwise the
   following happens.
3. Searches for an action attribute. We can set
   [HttpGet],[HttpPost],[HttpPut],etc over an action that will map that
   specific action with a HTTP verb.

Straight to your question, the create action has a HttpPost verb attribute. So theres a map between create and post. Thus http://localhost:5000/pizza will add a pizza to the DB
NOTE: make the route plural since it is a standard.

There is also further info here

It is an API controller. The section that describes this is on MS Learn: Routing to controller actions in ASP.NET Core: Attribute routing with Http verb attributes:

> When building a REST API, it's rare that you'll need to use [Route(...)] on an action method because the action accepts all HTTP methods. It's better to use the more specific HTTP verb attribute to be precise about what your API supports. Clients of REST APIs are expected to know what paths and HTTP verbs map to specific logical operations.
>
> REST APIs should use attribute routing to model the app's functionality as a set of resources where operations are represented by HTTP verbs. This means that many operations, for example, GET and POST on the same logical resource use the same URL. Attribute routing provides a level of control that's needed to carefully design an API's public endpoint layout.

So it doesn't matter how you name the methods. It's the attributes that make it accept a certain verb.

So it'll take your controller name (Pizza from PizzaController) and match the POST from the request to the Create method, as that's annotated with [HttpPost].

Now to further address the comments on your question:

> You have a controller which can either be at client or server. Most cases it is at server.

In the context of ASP.NET Core, controllers always run on the server.

> A HTTP request has 5 parts 1) Client sends a request which can either be a Get or Post. Post means the body of the request contains data. 2) Server receives the request. 3) Server processes the request 4) Server sends a response which can be a Get or Post. Get means there is no body. In this case it usually just a 200 OK. Post means there is a body 5) Client receives the response.

There are many more verbs. Most verbs can have a body, or omit one. You can POST without a body. You can GET with a body. The request has a verb (GET, POST, DELETE, ...), the response doesn't.

> The IActionResult is the data in the body of the request/response.

Well no. You can return an IActionResult with or without a body, but it has nothing to do with the request.

> The create method in this case is a Microsoft invention.

No, the "Create" mentioned here is from the C of CRUD.

> The body of the request/response is serialized/deserialized to the IActionResult.

What?

> The URL (route) determines what method is used to process the body of the message.

The URL and the verb.

> The actual data in the body is the IActionResult.

What?