从承诺返回数据然后链接

Question

I have a class method (for 'apollo-datasource-rest' that is supposed to fetch a plan from a plan_id . I need to hit two endpoints and combine the data. This works with Promise.all([promise1, promise2]) and then passes the user_ids on to the next Promise.all method that calls the GET /users endpoint multiple times. If I console.log out the usersArray that is returned, I get the array of users, but if I try to return that array, it doesn't get assigned to the objToReturn variable. I also need to add data from snapshot2 to the objToReturn but that is secondary.

  getPlanById = async ( planId ) => {
    const promise1 = new Promise((resolve) => {
      return resolve(this.get('/url1'))
    });
    const promise2 = new Promise((resolve) => {
      return resolve(this.get('/url2'))
    });    

    const objToReturn = await Promise.all([promise1, promise2])
      .then(([snapshot1, snapshot2]) => {
        return snapshot1.user_ids
      })
      .then((userIds) => {
        this.getUsersFromUserIds(userIds).then((usersArray) => {
          console.log(usersArray)
          // return usersArray doesn't assign to objToReturn
        })
      })
    return objToReturn
  }

  getUsersFromUserIds(userIds) {
    let userPromises = []
    userIds.forEach((uid) => {
      const promise = this.get(`/users/${uid}`)
      .then((response) => {
        if (response.status === 'success') {
          return response.data.user
        } else {
          return null
        }
      })
      userPromises.push(promise)
    })
    return Promise.all(userPromises).
      then((userPromiseData) => {
        return userPromiseData
      })
  }

Answer 1

You need to return the promise of this.getUsersFromUserIds(userIds) . So that the promise chain can work.

Eg

index.js :

class UserAPI {
  async getPlanById(planId) {
    const promise1 = Promise.resolve({ user_ids: [1, 2] });
    const promise2 = Promise.resolve();

    const objToReturn = await Promise.all([promise1, promise2])
      .then(([snapshot1, snapshot2]) => {
        return snapshot1.user_ids;
      })
      .then((userIds) => {
        // You need to return here
        return this.getUsersFromUserIds(userIds).then((usersArray) => {
          return usersArray;
        });
      });
    return objToReturn;
  }

  async getUsersFromUserIds(userIds) {
    return [
      { id: 1, name: 'a' },
      { id: 2, name: 'b' },
    ];
  }
}

const userAPI = new UserAPI();
userAPI.getPlanById(1).then((objToReturn) => {
  console.log('objToReturn: ', objToReturn);
});

The output in the console:

objToReturn:  [ { id: 1, name: 'a' }, { id: 2, name: 'b' } ]