Underscore.js: Map an array of objects to remove and combine duplicate data

Question

I'm new to the underscore js library and I am trying to reorganize some of my data so that it suits my application needs better. I have the following data coming in from my API:

{
    "id": "123456",
    "first_name": "John",
    "last_name": "Doe",
    "behaviours": [
        {
            "id": 17,
            "name": "Following Too Closely",
            "event_id": "01234-01234-01234",
            "event_number": "ABG4482",
        },
        {
            "id": 19,
            "name": "Not Looking Far Ahead",
            "event_id": "01234-01234-01234",
            "event_number": "ABG4482",
        },
        {
            "id": 19,
            "name": "Not Looking Far Ahead",
            "event_id": "01234-01234-01234",
            "event_number": "ABG4481",
        }
    ]
},
{
    "id": "123456",
    "first_name": "Jane",
    "last_name": "Doe",
    "behaviours": [
        {
            "id": 17,
            "name": "Following Too Closely",
            "event_id": "01234-01234-01234",
            "event_number": "ABG4482",
        },
        {
            "id": 19,
            "name": "Not Looking Far Ahead",
            "event_id": "01234-01234-01234",
            "event_number": "ABG4482",
        },
        {
            "id": 19,
            "name": "Not Looking Far Ahead",
            "event_id": "01234-01234-01234",
            "event_number": "ABG4481",
        }
    ]
}

I want to map the data so that I can pluck out the unique behaviour names, and create a new array that has the behaviours grouped. So my data would look like this:

{
    "id": "123456",
    "first_name": "John",
    "last_name": "Doe",
    "behaviours": [
        {
            "id": 17
            "name": "Following Too Closely",
            "events": [
                { 
                    "event_id": "01234-01234-01234",
                    "event_number": "ABG4482" 
                }
            ]
        },
        {
            "id": 19,
            "name": "Not Looking Far Ahead",
            "events": [
                {
                    "event_id": "01234-01234-01234",
                    "event_number": "ABG4482"
                },
                {
                    "event_id": "01234-01234-01234",
                    "event_number": "ABG4481"
                }
            ]
        }
    ]
},
{
    "id": "123456",
    "first_name": "Jane",
    "last_name": "Doe",
    "behaviours": [
        {
            "id": 17
            "name": "Following Too Closely",
            "events": [
                { 
                    "event_id": "01234-01234-01234",
                    "event_number": "ABG4482" 
                }
            ]
        },
        {
            "id": 19,
            "name": "Not Looking Far Ahead",
            "events": [
                {
                    "event_id": "01234-01234-01234",
                    "event_number": "ABG4482"
                },
                {
                    "event_id": "01234-01234-01234",
                    "event_number": "ABG4481"
                }
            ]
        }
    ]
}

I've currently got the following code which isn't doing a whole lot, I am stuck on this problem and I'm not sure how to go about it efficiently.

for (var i = $scope.eventData.drivers.length - 1; i >= 0; i--) {

    // Create an array containing only the unique behavior names
    var behaviourArray = _.uniq(_.pluck($scope.eventData.drivers[i].behaviours, 'name'));

    // Create a property containing a joined array of the behavior names
    $scope.eventData.drivers[i].behaviourNames = behaviourArray.join(', ');

    behaviourArray = _.map(behaviourArray, function(name) {
        return {
            'name': name,
            'events': []
        };
    });
};

I'm not sure how to push the event objects {event_id, and event_number} into the events array while matching the name of the behavior object with the new array's behavior object. Any help is appreciated.

salek · Accepted Answer · 2013-11-11 04:51:32Z

The following produces the exact structure you need your data in.

here's your original thing

var data = [{
  "id": "123456",
  "first_name": "John",
  "last_name": "Doe",
  "behaviours": [{
    "id": 17,
    "name": "Following Too Closely",
    "event_id": "01234-01234-01234",
    "event_number": "ABG4482",
  }, {
    "id": 19,
    "name": "Not Looking Far Ahead",
    "event_id": "01234-01234-01234",
    "event_number": "ABG4482",
  }, {
    "id": 19,
    "name": "Not Looking Far Ahead",
    "event_id": "01234-01234-01234",
    "event_number": "ABG4481",
  }]
}, {
  "id": "123456",
  "first_name": "Jane",
  "last_name": "Doe",
  "behaviours": [{
    "id": 17,
    "name": "Following Too Closely",
    "event_id": "01234-01234-01234",
    "event_number": "ABG4482",
  }, {
    "id": 19,
    "name": "Not Looking Far Ahead",
    "event_id": "01234-01234-01234",
    "event_number": "ABG4482",
  }, {
    "id": 19,
    "name": "Not Looking Far Ahead",
    "event_id": "01234-01234-01234",
    "event_number": "ABG4481",
  }]
}];

the cream!!!

_.each(data, function (driver) {
  driver.behaviours = _(driver.behaviours)
    .chain()
    .groupBy(function (x) {
      return x.id;
    })
    .map(function (g) {
      return {
        id: g[0].id,
        name: g[0].name,
        events: _.map(g, function (x) {
          return {
            event_id: x.event_id,
            event_number: x.event_number
          }
        })
      };
    })
    .value();
});

do a log

console.log(JSON.stringify(data));

the following is the output

[{
  "id": "123456",
  "first_name": "John",
  "last_name": "Doe",
  "behaviours": [{
    "id": 17,
    "name": "Following Too Closely",
    "events": [{
      "event_id": "01234-01234-01234",
      "event_number": "ABG4482"
    }]
  }, {
    "id": 19,
    "name": "Not Looking Far Ahead",
    "events": [{
      "event_id ": "01234-01234-01234",
      "event_number": "ABG4482"
    }, {
      "event_id": "01234-01234-01234",
      "event_number": "ABG4481"
    }]
  }]
}, {
  "id": "123 456",
  "first_name": "Jane",
  "last_name": "Doe",
  "behaviours": [{
    "id": 17,
    "name": "Following Too Closely",
    "events": [{
      "event_id": "01234-01234-01234",
      "event_number": "ABG4482"
    }]
  }, {
    "id": 19,
    "name": "Not Looking Far Ahead",
    "events": [{
      "event_id": "01234-0123 4-01234",
      "event_number": "ABG4482"
    }, {
      "event_id": "01234-01234-01234",
      "event_number": "ABG4481"
    }]
  }]
}]

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