从json中检索唯一值

Question

I know this should very easy, but I simply cannot get this thing to work. I have an object which has the following structure:

"name": "Machine 1",
"categories": [
  {
    "name": "Planned",
    "days": [
      {
        "id": 0,
        "date": "2015-09-14T00:00:00",
        "time": 768
      },
      {
        "id": 0,
        "date": "2015-09-15T00:00:00",
        "time": 1100
      },
      {
        "id": 0,
        "date": "2015-09-16T00:00:00",
        "time": 356
      }
    ]
  },
  {
    "name": "Item 1",
    "days": [
      {
        "id": 0,
        "date": "2015-09-14T00:00:00",
        "time": 1323
      },
      {
        "id": 0,
        "date": "2015-09-15T00:00:00",
        "time": 1475
      },
      {
        "id": 0,
        "date": "2015-09-16T00:00:00",
        "time": 668
      }
    ]
  },

So if I want to show it in a tree like structure, the returned object would look like this

• Array of machines
  • Each machine has array of categories
    • each category has a list of days

What I am trying to do instead of my current approach (manual iteration)

            angular.forEach(machine.categories, function (category, index) {
                angular.forEach(category.days, function (day, index) {
                    newData.labels.push(day.date);
                });
            });

is to use a already existing library (based on my research, underscore.js should be a perfect fit for this) and to do it properly (I am trying to learn, how to work with it).

So what I am trying to achieve is to get list of unique days in the date format. So my resulting object would look like this:

var result = ["2015-09-14", "2015-09-15", "2015-09-16"] (this one would be better)

Is there a way how to do it using the library (meaning without manual iteration)?

Answer 1

You could use Set for unique values

 var data = { "name": "Machine 1", "categories": [{ "name": "Planned", "days": [{ "id": 0, "date": "2015-09-14T00:00:00", "time": 768 }, { "id": 0, "date": "2015-09-15T00:00:00", "time": 1100 }, { "id": 0, "date": "2015-09-16T00:00:00", "time": 356 }] }, { "name": "Item 1", "days": [{ "id": 0, "date": "2015-09-14T00:00:00", "time": 1323 }, { "id": 0, "date": "2015-09-15T00:00:00", "time": 1475 }, { "id": 0, "date": "2015-09-16T00:00:00", "time": 668 }] }] }; var set = new Set(); data.categories.forEach(e => e.days.forEach(e => set.add(e.date))); document.write('<pre>' + JSON.stringify(Array.from(set)) + '</pre>'); 

Answer 2

Using underscore (bit verbose, assuming you parsed your JSON in a variable called data ):

var result = _.uniq(
               _.flatten(
                 _.map(data.categories, function(category) {
                   return _.map(_.pluck(category.days, 'date'), function(date) {
                     return date.replace(/T\d+:\d+:\d+$/, '');
                });
             })));