How to retrieve the key/value object in Json with Javascript?

Question

I have a weird problem.

First I retrieve several calls at the same time. And save the returned data in a variable called "values"

  function PrefsService($resource,PrefsResource,$q) {

    var initialize = function() {

      return $q
        .all(
          [PrefsResource.get({key:"TwentyFourHourTime"}),
          PrefsResource.get({key:"DecimalTime"}),
          PrefsResource.get({key:"startDayOfWeek"}),
          PrefsResource.get({key:"RoundingIncrement"}),
          PrefsResource.get({key:"RoundingOption"})
        ]
        )
        .then(function(values) {

          return values
        })

I use this piece of code in controller to see the returned value:

PrefsService
.initialize()
.then(function(values) {
console.log("values",values);
console.log("values[0]",values[0]);
console.log("values[0].result",values[0].result);
})

I want to use "values[0].result" get the result object. But it always gives me a value of "undefined".

Why?

Thx

At what point are you attempting to use `values[0].result`? [This may be related](http://stackoverflow.com/questions/14220321/how-to-return-the-response-from-an-asynchronous-call). — James Thorpe, Dec 09 '15 at 16:34
What you are explaining should work. I'm guessing there's more to it than your explanation. — Kevin B, Dec 09 '15 at 16:36
The return from initialize will be a promise. Are you calling initialize.then(...)? — Amy Blankenship, Dec 09 '15 at 16:39
With what you have shown, values[0].result is the correct way of getting it..May be you are accessing it before it resolves — Saurabh Tiwari, Dec 09 '15 at 16:39
You've updated it, but you appear to be logging `values.values` and `values.values.result`? And have strange syntax as pointed out by Jamiec - please ensure this is a true representation of your actual code. — James Thorpe, Dec 09 '15 at 16:47
@Bluesea - then you should do the work on the promises inside the `then` callback in the `PrefsService` so that you return the actual values to whatever calls `PrefsService.initialize()` instead of returning the promises, which is what it's doing right now. — Adam Jenkins, Dec 09 '15 at 17:04

score 0 · Answer 1 · answered Dec 09 '15 at 16:46

This syntax looks weird:

return {
    values
}

Its basically an object literal with a property name, but no value. In any case what you are tagging on to the initial all is unnecessary:

.then(function(values) {

      return {
        values
      }
    })

Just remove that part.

score 0 · Answer 2 · answered Dec 09 '15 at 16:47

0

The returned values are promises, use them as promises like you are supposed to:

PrefsService
.initialize()
.then(function(values) {
    values.map(function(valuePromise) {
       valuePromise.then(function(value) {
           console.log(value);
       });
    });
 });

answered Dec 09 '15 at 16:47

R. Salisbury

1,954
16
17

Because you're wrapping `values` in an object. Just return `values` not `{values}` and you will get an array, which will have the `map()` function. – R. Salisbury Dec 09 '15 at 16:57
1

That's because your doing this `return { values };` What you should be doing is `return values;` – Adam Jenkins Dec 09 '15 at 16:57

score 0 · Answer 3 · answered Dec 09 '15 at 17:01

The most straightforward way would be to return the actual values, not the promises:

  function PrefsService($resource,PrefsResource,$q) {

    var initialize = function() {

      return $q
        .all([
          PrefsResource.get({key:"TwentyFourHourTime"}),
          PrefsResource.get({key:"DecimalTime"}),
          PrefsResource.get({key:"startDayOfWeek"}),
          PrefsResource.get({key:"RoundingIncrement"}),
          PrefsResource.get({key:"RoundingOption"})
        ])
        .then(function(values) {
          var returnValues = [];
          values.forEach(function(v) { 
              v.then(function(a) { 
                  returnValues.push(a); 
              })
          });
          return returnValues;
        })
    };

    return {
        initialize:initalize;
    }
}


PrefsService
   .initialize()
   .then(function(values) {
      console.log(values); //an array of the actual values, not the promises
   })

TypeError: v.then is not a function at http://localhost/services/prefsService.js:27:13 at Array.forEach (native) — Bluesea, Dec 09 '15 at 17:09

How to retrieve the key/value object in Json with Javascript?

3 Answers3

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