How to refactor the following code to use q? [duplicate]

Question

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How do I convert an existing callback API to promises? (24 answers)

Closed 9 years ago.

New to q, I got a sample code as follow, what it does is, get an order, then get the owner of the order, append the name of the owner to the order so that the complete order can be displayed, how to change this to using Q (kriskowal/q)? Thanks,

db.get_order(order_id, function(err, order) {
users.get_user(order.user_id, function(err, user) {
    order['$user_name'] = user.name
    console.log(order)
  })
})

Answer 1

I am assuming that get_order function depends on the db object and also get_user depends on user object. If that is the case, then you need to invoke those methods with Q.ninvoke, like this

Q.ninvoke(db, "get_order", order_id)
.then(function(order) {
    return Q.ninvoke(user, "get_user", order.user_id);
})
.then(function(user) {
    console.log(user.name);
})
.catch(function(err) {
    console.error(err);
});