does a partial view always need a model passed from the top-level view?

Question

Here's a url describing partial views in MVC:

https://learn.microsoft.com/en-us/aspnet/core/mvc/views/partial

Based on this url it looks like partial views are bound to a model that's passed to it from the partial view's top-level/parent view. Is this the standard and expected way to implement partial views?

This seems to indicate that a partial view intended to be used from several different parent views should have some type of associated specialized class that can be used to return its data to multiple different viewmodel builders. Is this the correct interpretation of the MVC partial view architecture?

Answer 1

Yes. By default it uses the parent views (view) model. But you can always pass another model to it explicitly ( as long as the type of the model passing is the same type which the view is strongly typed to).

@Html.Partial("MyPartialView",Model)

Or

 @{ var data = new MyClass { SomeProperty = "SomeValue"};
 @Html.Partial("MyPartialView",data )

Assuming MyPartialView is strongly typed to MyClass

@model MyClass

For example, If your main view is strongly typed to Order class which has a Customer property like this

public class Order
{
  public int OrderId { set;get;}
  public Customer Customer { set;get;}
}
public class Customer
{
  public string Name { set;get;}
} 

You can call the partial view which is strongly typed to the Customer class from your main view by passing the Model.Customer

@model Order
<h2>@Model.OrderId</h2>
@Html.Partial("Customer",Model.Customer)

Assuming your Customer view is strongly typed to Customer type

@model Customer
<h2>@Model.Name</h2>

You can call the Customer partial view from anywhere as long as you have a Customer object to pass to it. ( IF your parent view is strongly typed to Customer class, you do not need to explicitly pass it)