Receiving complex data via WebAPI action

Question

I'm needing a way to convert a complex web request into .Net objects. I understand that WebAPI uses a default model binder, and that for complicated data, a custom model binder is needed.

Objects

Public Class LapMobileModel
    Public Property Type As Integer
    Public Property EndTime As String
    Public Property StartTime As String
End Class

Public Class RaceMobileModel
    Public Property RaceName As String
    Public Property UserId As Integer
    Public Property Laps As IEnumerable(Of LapMobileModel)
    Public Property numberOfRacers As String
    Public Property PreRacePosition As String
    Public Property PostRacePosition As String
End Class

Public Class RaceListMobileModel
    Public Property RaceList As IEnumerable(Of RaceMobileModel)
End Class

Action (in an ApiController)

Public Function SyncLapData(ByVal raceList As RaceListMobileModel) As String
    'stuff
    Return "OK"
End Function

And I have the skeleton of a custom model binder:

Imports System.Web.Http
Imports System.Web.Http.ModelBinding
Imports System.Web.Http.Controllers


Public Class EventDataModelBinder
    Implements IModelBinder

    Public Function BindModel(actionContext As HttpActionContext, 
                              bindingContext As ModelBindingContext) 
                              As Boolean Implements IModelBinder.BindModel
    End Function
End Class

Questions:

How do I use the actionContext to get to the data I need to build the RaceListMobileModel?

How do I properly store it in the bindingContext?

Right now, the data is being sent via a POST with JSON content.

Answer 1

Web api doesn't use model binding to bind data from request body. You should take a look of parameter binding instead. http://blogs.msdn.com/b/jmstall/archive/2012/05/11/webapi-parameter-binding-under-the-hood.aspx

For the json content, web api uses json.net serializer as default to bind the model. It supports nested models or collections. So I don't see anything unsupported in your models. Did you encounter any issue when deserializing a json? Or you have some special logic when binding the data?