How to return two Objects in a Promise using Sails?

问题

I'm using SailsJs v0.11.3 and I want to use Promises to avoid using nested callback but I don't know how to return two objects from one stage (.then()) to another one.

My code looks like this but I got undefined when trying to print start param on the third .then statement.

User.findOneById(userId)
.then(function (result) { // #1
    return result;
}).then( function (result_a) { // #2
    console.log('---------------- ' +  result_a );

    var result_b = User.findOneById(ownerId)
        .then(function (result) {
            console.log(result);
            return result;
        });

    return [result_a, result_b];
}).then( function (start, finish) { // #3
    console.log('***********************', start, finish);
    // do something when is done
}).catch( function (err) {
    // do something when is error
    console.log(err);
    res.json(err.status,
    {
        error: err
    });
})
.done(function () {
    res.json(200);
});

Console result:

---------------- [object Object]
*********************** [ { person_id: '567ab10de51dcf11001b066a',
    email: 'jvilas1993@gmail.com',
    permission_level: 3,
    reset_password_token: null,
    belongs_to: '0',
    signin_count: 3,
    status_active: true,
    last_signin_at: '2016-01-05T17:55:49.595Z',
    last_signin_ip: '0.0.0.0',
    encrypted_password: '$2a$10$tDSUsXm7nn2p4r8FczpCrubbTig/7hJmy3W5u5hrcmMHAiVBXYZ/C',
    id: '567ab10de51dcf11001b0669' },
  Promise {
    _bitField: 0,
    _fulfillmentHandler0: undefined,
    _rejectionHandler0: undefined,
    _progressHandler0: undefined,
    _promise0: undefined,
    _receiver0: undefined,
    _settledValue: undefined } ] undefined
{ person_id: '565f57b7cd451a110063eef9',
  email: 'rswomar@gmail.com',
  permission_level: 1,
  reset_password_token: '353635663537623763643435316131313030363365656638',
  belongs_to: '0',
  signin_count: 1,
  status_active: false,
  last_signin_at: '2015-12-02T20:42:30.434Z',
  last_signin_ip: '0.0.0.0',
  encrypted_password: '$2a$10$37EHaE6oED65gFHqh9sE0OBOTeD.txl8DTNYLxJwgws6NIwNQ73Ky',
  id: '565f57b7cd451a110063eef8' }

So, I'd like to know how can I return two objects or variables in the second .then to the third .then. I mean the result from the first query and another result made on the second query and receive those in the third .then?

I hope to explain my problem in the right way. Thanks in advance!

回答1:

Use bluebird's Promise.join() and Promise.spread() methods

  User.findOneById(userId)
    .then(function (result) { // #1
        return result;
    }).then( function (result_a) { // #2
        console.log('---------------- ' +  result_a );

        var result_b = User.findOneById(ownerId)
            .then(function (result) {
                console.log(result);
                return result;
            });

        return Promise.all([result_a, result_b]);
    }).spread( function (start, finish) { // #3
        console.log('***********************', start, finish);
        // do something when is done
    }).catch( function (err) {
        // do something when is error
        console.log(err);
        res.json(err.status,
        {
            error: err
        });
    })
    .done(function () {
        res.json(200);
    });

来源：https://stackoverflow.com/questions/34641985/how-to-return-two-objects-in-a-promise-using-sails