Cascade @typeparam in Blazor

Question

Can you somehow cascade the @typeparam ?

For instance in this scenario, pass the TItem to the Child without specifying it

Expected behavior:

<Parent TItem="User">
  <Child>
</Parent>

Current:

<Parent TItem="User">
  <Child TItem="User">
</Parent>

Answer 1

Not yet, but it is supposed to be coming with .NET 6.

From the docs:

In .NET 6 Preview 2, Blazor can now infer generic type parameters from ancestor components. Ancestor components must opt in to this behavior. An ancestor component can cascade a type parameter by name to descendants using the [CascadingTypeParameter] attribute. This attribute allows generic type inference to use the specified type parameter automatically with descendants that have a type parameter with the same name.

Answer 2

as of .NET 6.0 and later, you can use the [CascadingTypeParameter] attribute

Parent.razor

@attribute [CascadingTypeParameter(nameof(T))]
@typeparam T

Child.razor

@typeparam T // will be cascaded down from the parent