javascript - 使用下划线获取所有键和每个键的唯一值列表

Question

从对象数组开始，我需要获取所有键以及每个对象的所有唯一值的列表。问题是我事先不知道 key 。如果您知道键，则有很多解决方案，但在这种情况下，每个对象可以有任意数量的键，并且每个键都有一个值数组。下面的代码可以工作，但它相当复杂，必须有一个更简单的解决方案。

Made a working JSBIN here

输入:

[
    {
        key_1: [ attribute_value_1, attribute_value_2, ... ],
        key_2: [ attribute_value_3, attribute_value_4, ... ],
    },
    ...
] 

输出:

[
    {
        label: key_1,
        options: [ attribute_value_1, attribute_value_2, ... ]
    },
    {
        label: key_2,
        options: [ attribute_value_3, attribute_value_4, ... ]
    },
    ...
]

建议的解决方案:

    _.chain(input)
        .map(function (attr) {
            return _.keys(attr).map(function (key) {
                return {
                    key: key,
                    value: attr[key]
                };
            });
        })
        .flatten()
        .groupBy('key')
        .map(function (grouped_values, key) {
            // value = array of { key, value }
            return {
                label: key,
                options: _.chain(grouped_values)
                    .pluck('value')
                    .flatten()
                    .uniq()
                    .value()
            };
        })
        .value();

Answer 1

使用 lodash - 申请 _.mergeWith()输入数组，并使用定制器函数组合数组并获取唯一值。之后_.map()将结果转换为所需格式:

var input = [
  {
    key_1: [ "attribute_value_1", "attribute_value_2" ],
    key_2: [ "attribute_value_3", "attribute_value_4" ]
  },
  {
    key_1: [ "attribute_value_1", "attribute_value_5" ],
    key_2: [ "attribute_value_2", "attribute_value_3" ],
    key_5: [ "attribute_value_2", "attribute_value_3" ]
  }
];


var params = [{}].concat(input).concat(function (objValue, srcValue) { // create the params to apply to mergeWith
  if (_.isArray(objValue)) {
    return _.union(objValue, srcValue); // merge the arrays, and get the unique values
  }
});

var result = _.map(_.mergeWith.apply(_, params), function(value, key) { // merge all objects in the array, and map the results to required format
  return {
    label: key,
    options: value
    };
  });

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.16.2/lodash.min.js"></script>

如果你使用 ES6，你可以清理丑陋的 params 数组:

const input = [
  {
    key_1: [ "attribute_value_1", "attribute_value_2" ],
    key_2: [ "attribute_value_3", "attribute_value_4" ]
  },
  {
    key_1: [ "attribute_value_1", "attribute_value_5" ],
    key_2: [ "attribute_value_2", "attribute_value_3" ],
    key_5: [ "attribute_value_2", "attribute_value_3" ]
  }
];

const customizer = (objValue, srcValue) => {
  if (_.isArray(objValue)) {
    return _.union(objValue, srcValue); // merge the arrays, and get the unique values
  }
};

const result = _.map(_.mergeWith({}, ...input, customizer), (value, key) => ({ // merge all objects in the array, and map the results to required format
  label: key,
  options: value
}));

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.16.2/lodash.min.js"></script>