Unique Array Of Objects And Merge Duplications Using Lodash Or Underscore

I have an array of objects that can contain duplicates, but I'd like uniquify the array by a property, and then I want to merge properties of the duplicates conditionally. For exam

Solution 1:

You could do it using _.uniqWith, but it would require you to mutate one of the parameters before returning the boolean value of whether they are equal, so I don't recommend it.

A better option is to use _.groupBy followed by _.map in order to group the unique names, and then customize how you combine them. In your case, you can combine the same-named objects using _.assignWith and then give a logical or || operation as the combining function.

With ES6, it becomes nearly a one-liner:

var array = [{"name":"object1","propertyA":true,"propertyB":false,"propertyC":false},{"name":"object2","propertyA":false,"propertyB":true,"propertyC":false},{"name":"object1","propertyA":false,"propertyB":true,"propertyC":false}];
    
var updatedArray =
  _(array)
    .groupBy('name')
    .map(objs => _.assignWith({}, ...objs, (val1, val2) => val1 || val2))
    .value();
    
console.log(updatedArray);

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<scriptsrc="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>

Solution 2:

With plain Javascript, you could use a hash table as reference to unique objects with the same name and collect the values in a loop over the keys and update with logical OR.

var array = [{ name: 'object1', propertyA: true, propertyB: false, propertyC: false }, { name: 'object2', propertyA: false, propertyB: true, propertyC: false }, { name: 'object1', propertyA: false, propertyB: true, propertyC: false }],
    unique = array.reduce(function (hash) {
        returnfunction (r, a) {
            if (!hash[a.name]) {
                hash[a.name] = { name: a.name };
                r.push(hash[a.name]);
            }
            Object.keys(a).forEach(function (k) {
                if (k !== 'name') {
                    hash[a.name][k] = hash[a.name][k] || a[k];
                }
            });
            return r;
        };
    }(Object.create(null)), []);

console.log(unique);

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