Promise.all(…).spread is not a function when running promises in parallel

问题

I'm trying to run 2 promises in paralel with sequelize, and then render the results in a .ejs template, but I'm receiving this error:

 Promise.all(...).spread is not a function

This is my code:

var environment_hash = req.session.passport.user.environment_hash;
var Template  = require('../models/index').Template;
var List      = require('../models/index').List;

var values = { 
    where: { environment_hash: environment_hash,
             is_deleted: 0 
        }                    
};

template = Template.findAll(values);
list = List.findAll(values);


Promise.all([template,list]).spread(function(templates,lists) {

    res.render('campaign/create.ejs', {
        templates: templates,
        lists: lists
    });

});

How can I solve thhis?

回答1:

I'll make my comment into an answer since it solved your issue.

.spread() is not a standard promise method. It is available in the Bluebird promise library. Your code you included does not show that. Three possible solutions:

Access array values directly

You can just use .then(results => {...}) and access the results as results[0] and results[1].

Include the Bluebird Promise library

You can include the Bluebird promise library so you have access to .spread().

var Promise = require('bluebird');

Use destructuring in the callback arguments

In the latest versions of nodejs, you could also use destructuring assignment which kind of removes the need for .spread() like this:

Promise.all([template,list]).then(function([templates,lists]) {
    res.render('campaign/create.ejs', {templates, lists});
});

回答2:

You can write it without non-standard Bluebird features and keep less dependencies as well.

Promise.all([template,list])
  .then(function([templates,lists]) {
  };

ES6 Destructuring assignment

Promise.all([
  Promise.resolve(1),
  Promise.resolve(2),
]).then(([one, two]) => console.log(one, two));

回答3:

This is a Bluebird Promise feature and you can access it via Sequelize.Promise without installing Bluebird module itself

Sequelize.Promise.all(promises).spread(...)

回答4:

I needed to install BlueBird.

npm install bluebird

Then:

var Promise = require("bluebird");

来源：https://stackoverflow.com/questions/42750254/promise-all-spread-is-not-a-function-when-running-promises-in-parallel

标签

javascript

node.js

promise

sequelize.js