const Promise = require("bluebird");
const mongoose = require("mongoose");
mongoose.Promise = Promise;
And I want to use Promise.bind to share variable in the promise chain:
function getAutherOfBook(name)
{
return Book.findOne(
{
name: name
}, "-_id auther")
.then(doc =>
{
return doc.auther;
});
};
function geNationalityOfAuther(name)
{
return Auther.findOne(
{
name: name
}, "-_id nationality")
.then(doc =>
{
return doc.nationality;
});
};
getAutherOfBook("The Kite Runner")
.bind({})
.then(auther =>
{
this.auther = auther;
return geNationalityOfAuther(auther);
})
.then(nationality =>
{
console.log("auther: ", this.auther);
console.log("nationality: ", nationality);
})
.bind()
But I got the error: getAutherOfBook(...).bind is not a function
Maybe bluebird is not working for mongoose?
The problem you are having is that mongoose queries does not return full fledge promises -- directly quoting http://mongoosejs.com/docs/promises.html (v4.7.6)
// A query is not a fully-fledged promise, but it does have a `.then()`.
query.then(function (doc) {
// use doc
});
// `.exec()` gives you a fully-fledged promise
var promise = query.exec();
assert.ok(promise instanceof require('mpromise'));
In other words, the then function is syntax sugar and not a promise which is why the bind and other promise functions does not work.
To make it work, you either wrap it up in a full promise or use the exec function as suggested in the docs