Remember, that HTTP requests can include a content body
In ASP.NET, this content is assigned to a variable with the [FromBody] attribute:
[HttpPost]
public string[] Post([FromBody] string someContent)
{
// someContent holds the content of the request body
return new string[] { text };
}
Note that the [FromBody] attribute can only be used on one parameter
However, nothing prevents you from using a custom type variable
# Handling HttpPost Requests (continued)
ASP.NET deserializes the request content body into an object:
## Contents
public class Student
- [HTTP methods for RESTful APIs](#http-methods-for-restful-apis)
- [HTTP `POST` method](#http-post-method)
- [HTTP `PUT` method](#http-put-method)
- [HTTP `DELETE` method](#http-delete-method)
- [HTTP `PATCH` method](#http-patch-method)
{
## HTTP methods for RESTful APIs
public int Id { get; set; }
### RESTful API
public string Name { get; set; }
* We'll be extending our Web API into a full-blown ***RESTful API***
* More about REST in [Frontend Basics Lecture 3: REST Architecture](https://gitea.buutti.com/education/frontend-basics/src/branch/main/3-rest-architecture.md)
}
* A good idea to also check out [Frontend Basics Lecture 2: HTTP methods](https://gitea.buutti.com/education/frontend-basics/src/branch/main/2-http.md)
* We have so far implemented `GET` and `POST` methods for reading resources from the API and creating new ones to it, respectively
// In controller class:
* All the primary methods for following the uniform interface requirement are `GET`, `POST`, `PUT`, `PATCH` and `DELETE`
* Others exist, but these are by far most commonly used
[HttpPost]
* These methods correspond to ***CRUD*** operations *__Create__*, *__Read__*, *__Update__* and *__Delete__*
* CRUD describes what is done to a resource after a request is sent
public Contact Put(int id, [FromBody] Contact contact)
{
// Contacts = list of Contact objects, fetched from some repository
Contacts.Add(contact);
### Primary HTTP request methods
return contact;
The primary HTTP request methods with descriptions:
* ASP.NET knows to deserialize the content if the content type is set to JSON in the HTTP requests __headers__
## HTTP `POST` method
### Handling `HttpPost` Requests
* Remember that HTTP requests can include a content body
* In ASP.NET, this content is assigned to a variable with the `[FromBody]` attribute:
```csharp
[HttpPost]
public string[] Post([FromBody] string someContent)
{
// someContent holds the content of the request body
return new string[] { text };
}
```
* Note that the `[FromBody]` attribute can only be used on one parameter
* However, nothing prevents you from using a custom type variable
---
* ASP.NET deserializes the request content body into an object:
```csharp
// Models/Contact.cs
public class Contact
{
public int Id { get; set; }
public string Name { get; set; }
}
```
* ```csharp
// Controllers/ContactsController.cs
[HttpPost]
public Contact Put(int id, [FromBody] Contact contact)
{
// Contacts is a list of Contact objects, fetched from some repository
Contacts.Add(contact);
return contact;
}
```
### Creating a POST Request with Postman
#### Request headers
* ASP.NET knows to deserialize the content if the content type is set to JSON in the HTTP requests *__headers__*
* Headers are optional parameters that can be included in every HTTP request
* Headers are optional parameters that can be included in every HTTP request
* Headers are set in Key-Value format
* Headers are set in a Key-Value format
* When creating a request in Postman, to inform the server what type of content was just sent, add a new key "Content-Type" and set its value to "application/json" in the _Headers _ tab:
* When creating a request in Postman, to inform the server what type of content was just sent, add a new key `Content-Type` and set its value to `application/json` in the _Headers_ tab:
<divclass='centered'>
# Creating a POST Request with Postman (continued)
After setting the header,
</div>
select the Body tab,
#### Request body
change the content type to raw,
After setting the header,
1) select the Body tab,
select JSON from the dropdown menu, and
2) change the content type to raw,
3) select JSON from the dropdown menu, and
insert the content in JSON format
4) insert the content in JSON format
# Creating a POST Request with Postman - Example
Suppose the Post method from before is routed at http://localhost:54106/api/students:
# Exercise 1: Creating a POST Endpoint
Continue working on CourseAPI.
<divclass='centered'>
Create a Post method and endpoint which adds a new course to the list in the repository, with a running ID. Content and Author values are obtained from the request body:
</div>
# HTTP PUT
Use PUT to replace an existing resource, e.g. an element in a list, with a new one
#### Sending the request
The ID of the resource to be replaced should be in the request URI
* If the `POST` method is routed at `http://localhost:54106/api/contacts`:
The information about the new resource should be in the request body like in POST requests
<divclass='centered'>
# Handling HttpPut Requests
</div>
The ID is fetched from the URI and the contents from the request body
### Exercise 1: Creating a `POST` Endpoint
<!--_class: "exercise invert" -->
Filtering is used to copy all objects from the original list except for the new contact object, which comes from body
Continue working on the CourseAPI.
[HttpPut("{id}")]
1) Create a `POST` method and endpoint which adds a new course to the list in the repository with a running ID. Content and Author values are obtained from the request body:
public List<Contact> Put(int id, [FromBody] Contact contact)
## HTTP `PUT` method
{
* Use `PUT` to replace an existing resource, e.g. an element in a list, with a new one
* The ID of the resource to be replaced should be in the request URI
* The information about the new resource should be in the request body like in `POST` requests
// Contacts = list of Contact objects, fetched from some repository
<divclass='centered'>
List<Contact> updatedList = Contacts.Select(c => c.Id != id ? c : contact).ToList();
Contacts = updatedList;
</div>
return updatedList;
### Handling `HttpPut` requests
}
* The ID is fetched from the URI and the contents from the request body
* Filtering is used to copy all objects from the original list except for the new `contact` object, which comes from body
```csharp
// Controllers/ContactsController.cs
[HttpPut("{id}")]
public List<Contact> Put(int id, [FromBody] Contact contact)
{
// Contacts is a list of Contact objects, fetched from some repository
List<Contact> updatedList = Contacts.Select(c => c.Id != id ? c : contact).ToList();
Contacts = updatedList;
return updatedList;
}
```
# Exercise 2: Creating a PUT Endpoint
### Exercise 2: Creating a `PUT` Endpoint
* In CoursesController class, create a method for PUT requests with the URI api/courses/{id}
* In CoursesController class, create a method for PUT requests with the URI api/courses/{id}
* The ID of the course to be replaced with should be in the request URI and the contents of the new course should be in the request body.
* The ID of the course to be replaced with should be in the request URI and the contents of the new course should be in the request body.
@ -152,105 +170,103 @@ return updatedList;
* Return a 404 status code if a course with the corresponding ID does not exist
* Return a 404 status code if a course with the corresponding ID does not exist
* Test with Swagger/Postman
* Test with Swagger/Postman
# HTTP DELETE
## HTTP `DELETE` method
Use DELETE to delete an existing resource, e.g. an element in a list
* Use `DELETE` to delete an existing resource, e.g. an element in a list
* The ID of the resource to be deleted should be in the request URI
* As with the `GET` method, a body is not needed
The ID of the resource to be deleted should be in the request URI
### Handling `HttpDelete` Requests
As with GET method, a body is not needed
* The ID is fetched from the URI
```csharp
// Controllers/ContactsController.cs
[HttpDelete("{id}")]
public List<Contact> Delete(int id)
{
// Contacts = list of contact objects, fetched from some repository
* Create an endpoint for DELETE requests with the URI api/courses/{id}
* The ID of the course should be fetched from the URI
* The corresponding course should be removed from the list of courses in the repository
* The method should return the updated Courses list (for testing purposes)
* Return a 404 status code if a course with the corresponding ID does not exist
* Test with Postman
# HTTP PATCH
* Use PATCH to partially update a resource
* I.e. update some value inside of a resource
* This saves some resources as only a part of a resource has to be sent instead of an entire document (as opposed to PUT requests)
* Sending and handling PATCH requests with ASP.NET requires some extra work and the use of a third party package: [http://jsonpatch.com/](http://jsonpatch.com/)
# HTTP PATCH (continued)
* To handle PATCH requests in a standardized way, install and add the following NuGet packages to your project:
* Microsoft.AspNetCore.JsonPatch
* Microsoft.AspNetCore.Mvc.NewtonsoftJson
* Then, change the following line in Program.cs (ASP.NET 5: Startup.cs)...
borb
4 weeks ago
