Method handleFederationQuery

core/federation.go:290–314

handleFederationQuery checks if the request is a federation built-in (`_service` or `_entities`) and produces a JSON response. Returns handled=false when the query is a regular GraphQL document and should flow through the normal pipeline. Detection is intentionally a substring scan over the raw que

(r GraphqlReq)

// literal "_service" or "_entities" inside a string variable, which is
// vanishingly rare and acceptable for an opt-in mode.
func (gj *graphjinEngine) handleFederationQuery(r GraphqlReq) (handled bool, data []byte, err error) {
	q := r.query
	if len(q) == 0 {
		return false, nil, nil
	}
	hasService := bytesContainsToken(q, []byte("_service"))
	hasEntities := bytesContainsToken(q, []byte("_entities"))
	if !hasService && !hasEntities {
		return false, nil, nil
	}

	if hasEntities {
		return true, nil, errFederationEntitiesNotImplemented
	}

	sdl, err := gj.getFederationSDL()
	if err != nil {
		return true, nil, err
	}
	resp, err := jsonMarshalServiceSDL(sdl)
	if err != nil {
		return true, nil, err
	}
	return true, resp, nil
}

// getFederationSDL returns the cached SDL, building it on first use.
func (gj *graphjinEngine) getFederationSDL() (string, error) {