Module query_function 

Resolution of a function-backed root query field (#1329).

The engine half of the request:query trigger. A query that declares function = "<name>" is answered by a sandboxed function instead of by reading a relation, and this is the seam through which the engine reaches one — parallel to BeforeMutationGate, and for the same reason: fraiseql-core knows nothing about function runtimes, so it holds a trait object the application supplies. In fraiseql-server that object dispatches into the compiled schema’s functions section.

What the engine keeps

Everything except the value. The resolver is asked for the field’s data; the engine still:

• enforces requires_role and requires_actor, before asking;
• applies field-level RBAC to what comes back, so a function-backed field is not a hole in the scope gates every other field passes through;
• projects the selection set, recases, and stamps __typename with the same projector the SQL path uses.

That list is the argument for option A in #1329. A field that resolved outside the engine would have to re-implement every one of them, and would be wrong about one of them within a release.

Root fields only

There is no nested-field equivalent and there will not be one. A nested resolver runs once per row, so a function there is an N+1 measured in V8 isolates — ~5–8 ms each, against a documented cold read of ~5–15 ms for the whole query. Root-only makes “one invocation per query” a property of the shape, and the compiler refuses the nested spelling rather than documenting against it.

Structs

QueryFunctionRequest

The field a QueryFunctionResolver is being asked to answer.

Traits

QueryFunctionResolver

Answers a function-backed root query field.