CODEWITHSUNDEEP
javascriptunderscore.js
dlimes
dlimes

Reputation: 105

Create array of values from a nested object using _Underscore

I've been having a heck of a time trying to figure this out. Still relatively new to _Underscore JS and I'm attempting to create an array of unique values from an array of nested objects. Example data below:

[  
   {  
      "property":"prop1",
      "list":[  
         {  
            "description":"description blah",
            "type":"F",
            "values":{  
               "value1":30.0,
               "value2":0.0
            }
         },
         {  
            "description":"description blah",
            "type":"F",
            "values":{  
               "value1":30.0,
               "value2":0.0
            }
         }
      ]
   },
   {  
      "property":"prop2",
      "list":[  
         {  
            "description":"description blah",
            "type":"Q",
            "values":{  
               "value1":30.0,
               "value2":0.0
            }
         }
      ]
   }
]

What I'm attempting to get back is an array of ALL the UNIQUE nested "type" values. Example of data back below:

["F","Q"]

I've attempted _.pluck and _.map with little success. Would I need to utilize something different, such as chaining them? Appreciate any help I could get on this.

Upvotes: 1

Views: 594

Answers (3)

Gruff Bunny
Gruff Bunny

Reputation: 27986

Here's a solution that uses chaining:

let result = _.chain(data)
    .pluck('list')
    .flatten()
    .pluck('type')
    .uniq()
    .value();

This works by first plucking the lists from the data and flattening them. Then the type is plcuked from the list before finally calling uniq to get the unique types.

Upvotes: 2

adrice727
adrice727

Reputation: 1492

_.unique(_.flatten(_.map(myList, item => _.map(item.list, i => i.type))));

Underscore is not the greatest when it comes to composing functions since it takes data first. lodash-fp and ramda are much better in this regard.

Working fiddle: https://jsfiddle.net/8eLk7t15/

Upvotes: 0

tymeJV
tymeJV

Reputation: 104795

You can do this regular JS and reduce (sorry, I'm not very familiar with underscore, so I figured I'd offer a vanilla solution for now)

var uniqueValues = data.reduce(function(vals, d) {
    return vals.concat(d.list.reduce(function(listVals, l) {
        if (vals.indexOf(l.type) === -1 && listVals.indexOf(l.type) === -1) {
            listVals.push(l.type)
        }

        return listVals;
    }, []))
}, [])

Demo: https://jsfiddle.net/0dsdm7Lu/

Upvotes: 0

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