If i got view which inherits from:
System.Web.Mvc.ViewPage<Foo>
Where Foo has a property Bar with a type string
And view wants to render strongly typed partial view which inherits from:
System.Web.Mvc.ViewUserControl<string>
like this:
Html.RenderPartial("_Bar", Model.Bar);%>
Then why it will throw this:
The model item passed into the dictionary is of type 'Foo'
but this dictionary requires a model item of type 'System.String'.
when bar is not initialized?
More specific: why it passes Foo, where it should pass null?
Best Answer
As @Dennis points out, if the model value is null, it will use the existing model from the view. The reason for this is to support the ability to call a partial view using a signature that contains only the partial view name and have it reuse the existing model. Internally, all of the RenderPartial helpers defer to a single RenderPartialInternal method. The way you get that method to reuse the existing model is to pass in a null value for the model (which the signature that takes only a view name does). When you pass a null value to the signature containing both a view name and a model object, you are essentially replicating the behavior of the method that takes only the view name.
This should fix your issue: