website/versioned_docs/version-v20.0.0/guides/relay-resolvers/enabling.md
When using Relay Resolvers, we recommend configuring a fieldLogger in your Relay Enviornment in order to track errors which have been thrown within Relay resolver functions.
import { Environment, RecordSource, RelayFeatureFlags } from "relay-runtime";
import RelayModernStore from "relay-runtime/lib/store/RelayModernStore";
// It is recommended to log errors thrown by Resolvers
function fieldLogger(event) {
if(event.kind === "relay_resolver.error") {
// Log this somewhere!
console.warn(`Resolver error encountered in ${event.owner}.${event.fieldPath}`)
console.warn(event.error)
}
}
const environment = new Environment({
network: Network.create(/* your fetch function here */),
store: new RelayModernStore(new RecordSource()),
relayFieldLogger: fieldLogger
});
// ... create your Relay context with your environment
To opt-in the new syntax in a file, add //relay:enable-new-relay-resolver to the file
To convert files to the new syntax, run codemode: flow-runner codemod relay/migrateResolver <path>. The codemod doesn't support all cases, so you might need to modify some files manually after it runs.