Attribute 'Topic' is not valid on this declaration type. It is valid on 'Method' declarations only.

[LeXaMeN]

Is there an existing issue for this?

• I have searched the existing issues

Product

Hot Chocolate

Describe the bug

Documentation says:

We can even use the Topic attribute on dynamic arguments of the subscription field.
https://chillicream.com/docs/hotchocolate/v13/defining-a-schema/subscriptions#dynamic-topics

Visual Studio says:

Attribute 'Topic' is not valid on this declaration type. It is valid on 'Method' declarations only.

Steps to reproduce

Example:

public class Subscription
{
    [Subscribe]
    public Client ClientUpdated([Topic] int clientId, [EventMessage] Client client) => client;
}

Relevant log output

No response

Additional Context?

No response

Version

13.0.5

[tobias-tengler]

This was a breaking change as part of v13 as detailed here: https://chillicream.com/docs/hotchocolate/v13/migrating/migrate-from-12-to-13/#topicattribute

The documentation needs to be updated.

[williamdenton]

when the docs get updated you might want to note that nameof can be used to get the argument name

public class Subscription
{
    [Subscribe]
    // What's inbetween the curly braces must match an argument name.
    [Topic($"{nameof(author)}")]
    public Book BookPublished(string author, [EventMessage] Book book)
        => book;
}

[aokellermann]

when the docs get updated you might want to note that nameof can be used to get the argument name

public class Subscription
{
    [Subscribe]
    // What's inbetween the curly braces must match an argument name.
    [Topic($"{nameof(author)}")]
    public Book BookPublished(string author, [EventMessage] Book book)
        => book;
}

You need extra curly braces here: [Topic($"{{{nameof(author)}}}")]