POST JSON with MVC 4 API Controller

Question

I have this code:

   $.ajax({


        type: "POST",
        url: "/api/slide",
        cache: false,
        contentType: "application/json; charset=utf-8",
        data: '{"Title":"fghfdhgfdgfd"}',
        dataType: "json",

An this is my controler:

public class SlideController : ApiController
{

    // POST /api/Slide
    public void Post(string Title)
    {
    }

When I run the code and call the /api/Slide, the [Title] has no data and is null.

How do I post JSON to the API controller?

POST http://127.0.0.2:81/api/slide HTTP/1.1
Host: 127.0.0.2:81
Connection: keep-alive
Content-Length: 18
Origin: http://127.0.0.2:81
X-Requested-With: XMLHttpRequest
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1
Content-Type: application/json; charset=UTF-8
Accept: application/json, text/javascript, */*; q=0.01
Referer: http://127.0.0.2:81/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3

Title=fghfdhgfdgfd

Answer 1

Define a view model:

public class SlideViewModel
{
    public string Title { get; set; }
}

then have your controller action take this view model as argument:

public class SlideController : ApiController
{
    // POST /api/Slide
    public void Post(SlideViewModel model)
    {
        ...
    }
}

finally invoke the action:

$.ajax({
    type: 'POST',
    url: '/api/slide',
    cache: false,
    contentType: 'application/json; charset=utf-8',
    data: JSON.stringify({ title: "fghfdhgfdgfd" }),
    success: function() {
        ...    
    }
});

The reason for that is that simple types such as strings are bound from the URI. I also invite you to read the following article about model binding in the Web API.

Answer 2

Ensure the object you are trying to convert to has a default (empty) constructor.

Rule of thumb: If you want to deserialize to an object, you need to make it simple for the objects to be created. These guidelines can help:

• All properties that are to be passed around must be public

• the object needs to able to be constructed without any parameters.

This JSON string/object for example:

{ Name: "John Doe", Phone: "123-456-7890", Pets: [ "dog", "cat", "snake" ] }

can be converted to an object from the following class:

 public class Person {

     public string Name { get; set; }
     public string Phone { get; set; }
     public string[] Pets { get; set; }

  }

or this one:

public class Person {

   public string Name { get; set; }
   public string Phone { get; set; }
   public string[] Pets { get; set; }
   public Person() {}
   public Person(string name, string phone) {
      Name = name;
      Phone = phone;
   }

}

or this one:

public class Person {

    public string Name { get; set; }
    public string Phone { get; set; }
    public string[] Pets { get; set; }
    public Person() {}


 }

but not this one

public class Person {

    public string Name { get; set; }
    public string Phone { get; set; }
    public string[] Pets { get; set; }
    public Person(string name, string phone) {
      Name = name;
      Phone = phone;
    }

}

Now let ASP.NET MVC 4 do the rest

public class PersonController : ApiController
{
        // .. other actions 
        public HttpResponseMessage PostPerson(Person person)
        {
            if ( null != person)
                // CELEBRATE by doing something with your object
            else 
                // BE SAD and throw and exception or pass an error message

        }
        // .. other actions 
}

If your class cannot have a default constructor or if you don't have access to the source code for the class, you can create an adapter class that

• has a default constructor
• exposes those properties that need to be public

Using the Person class above with no default constructor, an adapter could look like

public class PersonAdapter {

    public Person personAdaptee;

    public string Name {
        get { return personAdaptee.Name; }
        set { personAdaptee.Name = value }
    }

    public string Phone {
        get { return personModel.Phone; }
        set { personModel.Phone = value; }
    }

    public string[] Pets {
        get { return personAdaptee.Pets; }
        set {personAdaptee.Pets = value }
    }

    public PersonAdapter() {

        personAdaptee = new Person("", "", null);

    }

}

Now let ASP.NET MVC 4 do the rest

public class PersonController : ApiController
{
        // .. other actions 
        public HttpResponseMessage PostPerson(PersonAdapter person)
        {
            if ( null != person)
                // CELEBRATE by doing something with your object
            else 
                // BE SAD and throw and exception or pass an error message

        }
        // .. other actions 
}