Leveraging async/await in conjunction with callback functions

Question

Leveraging async/await in conjunction with callback functions

I am in the process of creating a service layer on top of mongoDB. I have a User object that contains an array of referenced Achievements.

Once the user is authenticated using JWT or another method, I go into the service layer and retrieve the relationship in the following way.

findForUser(userId: string | Types.ObjectId): Promise<Achievement[]> {
  return new Promise((resolve) => {
    UserSchema.findOne({ _id: userId },
      async (err: any, user: User) => {
        const AchievementMap: Achievement[] = [];

        if (err) throw new Error(err);
        user.achievements?.forEach((a) => {
          // @ts-ignore
          AchievementMap.push(a);
        });
        resolve(AchievementMap);
      });
  });
}

How can I implement the async/await approach to handle the callback function passed to UserSchema.findOne?

javascript typescript async-await

Answer 1

Answer №1

findOne provides an awaitable result, eliminating the need for a callback function. Avoid mixing callbacks with async/await as it can lead to confusion. The best way to retrieve data from a promise is by utilizing resolve within the promise executor.

Consider refactoring your code to be entirely async for a cleaner and more streamlined approach:

async fetchAchievementsForUser(userId: string | Types.ObjectId): Promise<Achievement[]> {
    const user = await UserSchema.findOne({ _id: userId });

    const achievementList: Achievement[] = [];
    user.achievements?.forEach(achievement => {
        achievementList.push(achievement);
    });
    return achievementList;
}

Answer 2

findOne provides an awaitable result, eliminating the need for a callback function. Avoid mixing callbacks with async/await as it can lead to confusion. The best way to retrieve data from a promise is by utilizing resolve within the promise executor.

Consider refactoring your code to be entirely async for a cleaner and more streamlined approach:

async fetchAchievementsForUser(userId: string | Types.ObjectId): Promise<Achievement[]> {
    const user = await UserSchema.findOne({ _id: userId });

    const achievementList: Achievement[] = [];
    user.achievements?.forEach(achievement => {
        achievementList.push(achievement);
    });
    return achievementList;
}

Answer 3

Answer №2

What is the async/await method for handling callback results?

Using the async and await keywords allows for better management of promises, not callbacks.

The goal of the code provided is to incorporate a promise-based approach into a function that originally used callbacks.

Now with a promise in place, you can easily await the output of the findForUser function.

It's important to note that using async and await does not replace the need to create a promise.

Answer 4

What is the async/await method for handling callback results?

Using the async and await keywords allows for better management of promises, not callbacks.

The goal of the code provided is to incorporate a promise-based approach into a function that originally used callbacks.

Now with a promise in place, you can easily await the output of the findForUser function.

It's important to note that using async and await does not replace the need to create a promise.

Leveraging async/await in conjunction with callback functions

Answer №1

Answer №2

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