How can I get unique array from a collection of nested objects with lodash? - angularjs

Question

I have the following collection:
"items": [{
"id": 1,
"title": "Montrachet",
"imageUrl": "http://winebuff.com.hk/products_image/3376-Ramonet-ChassagneMontrachetBlanc.jpg",
"imageUrls": [
"http://winebuff.com.hk/products_image/3376-Ramonet-ChassagneMontrachetBlanc.jpg",
"http://media.riepenau.com/wines/17973_b.jpg",
"http://lorempixel.com/400/400/food/3"
],
"properties": [
{"description" : "Kırmızı Şaraplar Desc"},
{"region" :"Bordeaux"},
{"age": "16"},
{"producer" :"Kayra"},
{"grapeType":"Espadeiro"}
],
"priceGlass": "1",
"priceBottle": "2",
"year": "1999"
},
{
"id": 2,
"title": "Montrachet2",
"imageUrl": "http://winebuff.com.hk/products_image/3376-Ramonet-ChassagneMontrachetBlanc.jpg",
"imageUrls": [
"http://winebuff.com.hk/products_image/3376-Ramonet-ChassagneMontrachetBlanc.jpg",
"http://media.riepenau.com/wines/17973_b.jpg",
"http://lorempixel.com/400/400/food/3"
],
"properties": [
{"description" : "Kırmızı Şaraplar Desc"},
{"region" :"Bordeaux"},
{"age": "16"},
{"producer" :"Kayra"},
{"grapeType":"Chardonnay"}
],
"priceGlass": "1",
"priceBottle": "2",
"year": "1999",
}
]
I want to grab unique grapeTypes from that collection. The returning array shold be ["Chardonnay","Espadeiro"]
What is the best way to do it with lodash?

Answer 1

I think this combination of pluck, map and filter should do it:
var result = _.chain(obj.items).pluck('properties').map(function(obj) {
return _.filter(obj, function(prop) {
return prop.grapeType;
})[0].grapeType;
}).uniq().value();
console.log(result);
Check the demo run below.
// Code goes here
var obj = {
items: [{
"id": 1,
"title": "Montrachet",
"imageUrl": "http://winebuff.com.hk/products_image/3376-Ramonet-ChassagneMontrachetBlanc.jpg",
"imageUrls": [
"http://winebuff.com.hk/products_image/3376-Ramonet-ChassagneMontrachetBlanc.jpg",
"http://media.riepenau.com/wines/17973_b.jpg",
"http://lorempixel.com/400/400/food/3"
],
"properties": [{
"description": "Kırmızı Şaraplar Desc"
}, {
"region": "Bordeaux"
}, {
"age": "16"
}, {
"producer": "Kayra"
}, {
"grapeType": "Espadeiro"
}
],
"priceGlass": "1",
"priceBottle": "2",
"year": "1999"
},
{
"id": 2,
"title": "Montrachet2",
"imageUrl": "http://winebuff.com.hk/products_image/3376-Ramonet-ChassagneMontrachetBlanc.jpg",
"imageUrls": [
"http://winebuff.com.hk/products_image/3376-Ramonet-ChassagneMontrachetBlanc.jpg",
"http://media.riepenau.com/wines/17973_b.jpg",
"http://lorempixel.com/400/400/food/3"
],
"properties": [{
"description": "Kırmızı Şaraplar Desc"
}, {
"region": "Bordeaux"
}, {
"age": "16"
}, {
"producer": "Kayra"
}, {
"grapeType": "Chardonnay"
}
],
"priceGlass": "1",
"priceBottle": "2",
"year": "1999",
}
]
};
var result = _.chain(obj.items).pluck('properties').map(function(obj) {
return _.filter(obj, function(prop) {
return prop.grapeType;
})[0].grapeType;
}).uniq().value();
document.write(JSON.stringify(result));
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/3.8.0/lodash.js"></script>
UPD. If grapeType can be missing from properties then the script should be
var result = _.chain(obj.items).pluck('properties').map(function(obj) {
return (_.filter(obj, function(prop) {
return prop.grapeType;
})[0] || {}).grapeType;
}).compact().uniq().value();

Answer 2

Here's one way to do it with lodash:
_(items)
.pluck('properties')
.map(function(item) {
return _.find(item, _.ary(_.partialRight(_.has, 'grapeType'), 1));
})
.pluck('grapeType')
.uniq()
.value();
First, you get the properties arrays using pluck(). Next, you use find() to get the first object in this array that has a grapeType property. This is done using has(), and partially-applying the argument to build the callback function.
Next, you use pluck() again to get the actual property values. Finally, uniq() ensures there are no duplicates.