Web API complex parameter properties are all null

Question

I have a Web API service call that updates a user\'s preferences. Unfortunately when I call this POST method from a jQuery ajax call, the request parameter object\'s proper

Answer 1

Maybe it will help, I was having the same problem.

Everything was working well, and suddently, every properties was defaulted.

After some quick test, I found that it was the [Serializable] that was causing the problem :

public IHttpActionResult Post(MyComplexClass myTaskObject)
{
    //MyTaskObject is not null, but every member are (the constructor get called).
}

and here was a snippet of my class :

[Serializable]  <-- have to remove that [if it was added for any reason..]
public class MyComplexClass()
{
     public MyComplexClass ()
     {
        ..initiate my variables..
     }

     public string blabla {get;set;}
     public int intTest {get;set;
}

Answer 2

I came across the same issue. The fix needed was to ensure that all serialize-able properties for your JSON to parameter class have get; set; methods explicitly defined. Don't rely on C# auto property syntax! Hope this gets fixed in later versions of asp.net.

Answer 3

So there are 3 possible issues I'm aware of where the value does not bind:

1. no public parameterless ctor
2. properties are not public settable
3. there's a binding error, which results in a ModelState.Valid == false - typical issues are: non compatible value types (json object to string, non-guid, etc.)

So I'm considering if API calls should have a filter applied that would return an error if the binding results in an error!

Answer 4

A bit late to the party, but I had this same issue and the fix was declaring the contentType in your ajax call:

    var settings = {
        HelpText: $('#help-text').val(),
        BranchId: $("#branch-select").val(),
        Department: $('input[name=departmentRadios]:checked').val()

    };

$.ajax({
        url: 'http://localhost:25131/api/test/updatesettings',
        type: 'POST',
        data: JSON.stringify(settings),
        contentType: "application/json;charset=utf-8",
        success: function (data) {
            alert('Success');
        },
        error: function (x, y, z) {
            alert(x + '\n' + y + '\n' + z);
        }
    });

And your API controller can be set up like this:

    [System.Web.Http.HttpPost]
    public IHttpActionResult UpdateSettings([FromBody()] UserSettings settings)
    {
//do stuff with your UserSettings object now
        return Ok("Successfully updated settings");
    }

Answer 5

In my case problem was solved when i added

get{}set{}

to parameters class definition:

public class PreferenceRequest
{
    public int UserId;
    public bool usePopups {get; set;}
    public bool useTheme {get; set;}
    public int recentCount {get; set;}
    public string[] detailsSections {get;set;}
}

enstead of:

   public class PreferenceRequest
    {
        [Required]
        public int UserId;
        public bool usePopups;
        public bool useTheme;
        public int recentCount;
        public string[] detailsSections;
    }

Answer 6

I guess problem is that your controller is expecting content type of [FromBody],try changing your controller to

public HttpResponseMessage Post(PreferenceRequest request)

and ajax to

$.ajax({
    type: "POST",
    data: JSON.stringify(request);,
    dataType: 'json',
    contentType: "application/json",
    url: "http://localhost:1111/service/User",

By the way creating model in javascript may not be best practice.