POST JSON with MVC 4 API Controller

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 
}

Try this:

$.ajax({
    type: "POST",
    url: "/api/slide",
    data: { Title: "fghfdhgfdgfd" }
});

It is the quotes around the data attribute which are causing this:

i.e >> data: { Title: "fghfdhgfdgfd" }
not >> data: '{ Title: "fghfdhgfdgfd" }'

UPDATE:
Also your controller seems a little strange, although it is hard to tell without seeing your routing, etc.

I would expect to see something more like this:

public class SlideController : ApiController
{
    public HttpResponseMessage PostSlide(string Title)
    {
        // Do your insert slide stuff here....

        string uri = Url.Link("DefaultApi", new { id = item.Id });
        response.Headers.Location = new Uri(uri);
        return response;
    }
}

Clearly, you will also need to update the URL in your jQuery too.

Take a look here:

http://www.asp.net/web-api/overview/getting-started-with-aspnet-web-api/tutorial-your-first-web-api

ANOTHER UPDATE:

It would be usual to create a CLR object to match your Json and use the MVC model binder to bind directly to that. If you don't want to do that you can bind to an object and deserialize into a Dictionary:

// POST api/values
public void Post(object json)
{
    Dictionary<string, string> values = JsonConvert.DeserializeObject<Dictionary<string, string>>(json.ToString());
    var x = values["Title"];
}

Cast the action parameter to FromBody i.e:

public class SlideController : ApiController
{

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

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

Controller is

public class SlideController : ApiController
{

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

Your url is not valid, url must address the action Post in Slide controller

edit your url to url:"~/ControllerName/ActionName" in this context must be Url:"~/Slide/Post"