GraphQL Logger Middleware

graphql-logger.ts

import { isAsyncIterable } from "@n1ru4l/push-pull-async-iterable-iterator";

type MaybePromise<T> = Promise<T> | T;

const map = <T, O>(map: (input: T) => Promise<O> | O) =>
  async function* mapGenerator(asyncIterable: AsyncIterableIterator<T>) {
    for await (const value of asyncIterable) {
      yield map(value);
    }
  };

export const applyGraphQLMiddleware = <T>(apply: (target: T) => MaybePromise<T>) => (
  input: MaybePromise<AsyncIterableIterator<T> | T>
): MaybePromise<AsyncIterableIterator<T> | T> => {
  const handler = (
    result: AsyncIterableIterator<T> | T
  ): AsyncIterableIterator<T> | MaybePromise<T> => {
    if (isAsyncIterable(result)) {
      return AsyncIteratorUtil.map(apply)(result);
    } else {
      return apply(result);
    }
  };
  return input instanceof Promise ? input.then(handler) : handler(input);
};

// Usage
import { flow } from "fp-ts/function";
import { ExecutionResult, execute as originalExecute, subscribe as originalSubscribe } from "graphql";

const graphQLErrorLogger = (result: ExecutionResult): ExecutionResult => {
  if (result.errors) {
    for (const error of result.errors) {
      console.error(error.originalError);
    }
  }

  return result;
};

const execute = flow(
  liveQueryStore.execute,
  applyGraphQLMiddleware(graphQLErrorLogger)
);
  
const subscribe = flow(
  originalSubscribe,
  applyGraphQLMiddleware(graphQLErrorLogger)
);