Refactor ID to add formatter via placeholder

[benmccallum]

Is your feature request related to a problem?

It's currently impossible (AFAIK) to determine whether an argument / input field has been setup as an ID field in cases where the [ID] attribute isn't used (which can be spotted in reflection).

Currently the way that polymorphic ids library does it is to look for the attribute, but we can't support fluent-style setup using .ID()
Code.

The ID descriptor extensions set it up in OnBeforeCompleteType, so I can't look for the GlobalIdInputFormatter on args to know if the arg/field is an ID (and insert mine before it). There's essentially a race condition.

The solution you'd like

On a call Michael said it'd be good to refactor this to use the same technique that some field middleware is added, like UsePaging, by having the extension method insert a placeholder formatter and swapping the real one in later in the type interceptor.

• WellKnownFormatterNames/WellKnownFormatterTypes.GlobalIdInputValueFormatter would mean we could look for it as an external library.

Alternatively, all the ID descriptor extensions could add a flag into the temporary context data I suppose.

Product

Hot Chocolate

[michaelstaib]

We have now named fromatters so you can inspect the configuration for them.