javascript - How do I reduce multiple Promise.all?

问题

I am trying to use a Promise.all inside of a reduce and cannot get my function to work, unless there is only one user in my array. The starting object of the reduce is a Promise. The first time through the reduce, the Promise has .all available on it. The second time through, the .all is not available.

return UserQueries.addUsersOnCasefileCreate(input).then(users => {
  return users.reduce((promise, user) => {
    return promise.all([
      AddressQueries.addAddress(user.address, user.userId, input.orgId),
      EmailQueries.addEmail(user.emails, user.userId, input.orgId),
      PhoneQueries.addPhones(user.phones, user.userId, input.orgId)
    ])
    .then(() => Promise.resolve(user))
  }, Promise);
})

How could I perform this operation?

回答1:

You initialize with Promise which is a function, though return a resolved Promise object, where the two are not the same.

You can initialize with Promise.resolve(), call promise.then(), then return Promise.all() with .then() chained within first .then(), which passes Promise object to next iteration at .reduce().

return UserQueries.addUsersOnCasefileCreate(input).then(users => {
  return users.reduce((promise, user) => {
    return promise.then(() => Promise.all([
      AddressQueries.addAddress(user.address, user.userId, input.orgId),
      EmailQueries.addEmail(user.emails, user.userId, input.orgId),
      PhoneQueries.addPhones(user.phones, user.userId, input.orgId)
    ]))
    .then(() => user))
  }, Promise.resolve());
})

回答2:

There's no need to use reduce(). Just map the things and wait them all.

return UserQueries.addUsersOnCasefileCreate(input).then(users => {
  return Promise.all(users.map((user) => {
    return Promise.all([
      AddressQueries.addAddress(user.address, user.userId, input.orgId),
      EmailQueries.addEmail(user.emails, user.userId, input.orgId),
      PhoneQueries.addPhones(user.phones, user.userId, input.orgId)
    ]);
  }));
});

来源：https://stackoverflow.com/questions/43433643/javascript-how-do-i-reduce-multiple-promise-all

标签

javascript

promise

reduce