Programmatically adding properties to an MVC model at runtime

Question

I am trying to create properties in my model programmatically when the application is run. I\'ve tried to follow the answer by Darin Dimitrov on this post How to create con

Answer 1

You are missing 2 hidden fields in your main view:

@ModelType MyApp.DomainModel.MyTest.MyViewModel

@Using Html.BeginForm()
    For i = 0 To Model.Controls.Length - 1
        @<div> 
            @Html.HiddenFor(Function(model) model.Controls(i).Type) 
            @Html.HiddenFor(Function(model) model.Controls(i).Name) 
            @Html.EditorFor(Function(model) model.Controls(i)) 
        </div> 
    Next
    @<input type="submit" value="OK" /> 
End Using

In your code you only have a single EditorFor call for the Controls property but you never specify the type of the control through a hidden field which is used by the custom model binder.

---

UPDATE:

I have also fixed the original model binder which contained a bug as it is better to override the CreateModel method instead of the BindModel:

Public Class ControlModelBinder
Inherits DefaultModelBinder
Protected Overrides Function CreateModel(controllerContext As ControllerContext, bindingContext As ModelBindingContext, modelType As Type) As Object
    Dim type = bindingContext.ValueProvider.GetValue(Convert.ToString(bindingContext.ModelName) & ".Type")
    If type Is Nothing Then
        Throw New Exception("The type must be specified")
    End If

    Dim model As Object = Nothing
    Select Case type.AttemptedValue
        Case "textbox"
            If True Then
                model = New TextBoxViewModel()
                Exit Select
            End If
        Case "checkbox"
            If True Then
                model = New CheckBoxViewModel()
                Exit Select
            End If
        Case "ddl"
            If True Then
                model = New DropDownListViewModel()
                Exit Select
            End If
        Case Else
            If True Then
                Throw New NotImplementedException()
            End If
    End Select

    bindingContext.ModelMetadata = ModelMetadataProviders.Current.GetMetadataForType(Function() model, model.[GetType]())
    Return model
End Function
End Class