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使用路径从对象提取数据-包括数组中的所有数据

flatmap lodash javascript

sixtyfootersdude · 技术社区 · 6 年前

我正试图用火山灰来解决以下问题。我知道如何使用for循环来解决问题,但是我正在寻找解决问题的现代函数方法。

我有以下数据:

const data = {
    people: [
        {
            name: "Bob",
            vehicles: [
                {
                    model: "Mazda"
                    tires: [
                        { pressure: 20 },
                        { pressure: 22 },
                        { pressure: 23 },
                        { pressure: 21 },
                    ]
                },
                {
                    model: "Harley Davidson"
                    tires: [
                        { pressure: 20 }
                        { pressure: 25 }
                    ]
                }
            ]
        },
        {...},
        {...},
        {...},
    ]
}

从中,我想提取每个人的轮胎气压列表。所以像这样:

[20, 22, 23, 21, 20, 25, ... ]

我要找的是一个我可以这样调用的方法:

const path = 'people.vehicles[*].tires[*].pressure';
const tirePressure = _.methodName(data, path);

我知道Lodash支持一些类似的功能,比如 _.at(object, ['a[0].b.c', 'a[1]']); (link) 但据我所知,它不支持折叠整个数组。

4 回复 | 直到 6 年前

jannis Anjali 6 年前

Lodash's flatMap flatMapDeep

const data = {
    people: [
        {
            name: "Bob",
            vehicles: [
                {
                    model: "Mazda",
                    tires: [
                        { pressure: 20 },
                        { pressure: 22 },
                        { pressure: 23 },
                        { pressure: 21 },
                    ]
                },
                {
                    model: "Harley Davidson",
                    tires: [
                        { pressure: 20 },
                        { pressure: 25 }
                    ]
                }
            ]
        }
    ]
};


const pressures = _(data.people)
  .flatMap(_.property('vehicles'))
  .flatMap(_.property('tires'))
  .map(_.property('pressure'))
  .value();

console.log(pressures);

<script src="https://cdn.jsdelivr.net/npm/lodash@4.17.10/lodash.min.js"></script>

Muhammad Usman 6 年前

JS

.map

const data = {
    people: [
        {
            name: "Bob",
            vehicles: [
                {
                    model: "Mazda",
                    tires: [
                        { pressure: 20 },
                        { pressure: 22 },
                        { pressure: 23 },
                        { pressure: 21 },
                    ]
                },
                {
                    model: "Harley Davidson",
                    tires: [
                        { pressure: 20 },
                        { pressure: 25 }
                    ]
                }
            ]
        }
    ]
}
var x=  data.people[0].vehicles.map(o=> o.tires.map(i=> i.pressure))

console.log(x.join(",").split(","))

Leonid Pyrlia 6 年前

reduce

const data={people:[{name:"Bob",vehicles:[{model:"Mazda",tires:[{pressure:20},{pressure:22},{pressure:23},{pressure:21}]},{model:"Harley Davidson",tires:[{pressure:20},{pressure:25}]}]}]};

const result = data.people.reduce((all, {name, vehicles}) => {

  const pressures  = vehicles.reduce((total, {tires}) => {
    tires.forEach(({pressure}) => total.push(pressure));
    return total;
  }, []);

  all[name] = pressures;

  return all;

}, {});

console.log(result);

Nina Scholz 6 年前

pressure

function getPressures(o) {
    return [].concat(...Object.entries(o).map(([key, value]) =>
        key === 'pressure'
            ? value
            : value && typeof value === 'object'
                ? getPressures(value)
                : []
    ));
}

var data = { people: [{ name: "Bob", vehicles: [{ model: "Mazda", tires: [{ pressure: 20 }, { pressure: 22 }, { pressure: 23 }, { pressure: 21 }] }, { model: "Harley Davidson", tires: [{ pressure: 20 }, { pressure: 25 }] }] }] };

console.log(getPressures(data));

.as-console-wrapper { max-height: 100% !important; top: 0; }

function get(object, path) {

    function iter(o, p, i) {
        if (i === parts.length) {
            result[p.join('.')] = o;
            return;
        }
        if (!o || typeof o !== 'object') {
            return;
        }
        if (parts[i] === '*') {
            Object
                .entries(o)
                .forEach(([k, v]) => iter(v, p.concat(k), i + 1));
            return;
        }
        if (parts[i] in o) {
            iter(o[parts[i]], p.concat(parts[i]), i + 1);
        }
    }

    var result = {},
        parts = path.split('.');

    iter(object, [], 0);
    return result;
}

var data = { people: [{ name: "Bob", vehicles: [{ model: "Mazda", tires: [{ pressure: 20 }, { pressure: 22 }, { pressure: 23 }, { pressure: 21 }] }, { model: "Harley Davidson", tires: [{ pressure: 20 }, { pressure: 25 }] }] }] },
    result = get(data, 'people.*.vehicles.*.tires.*.pressure'),
    values = Object.values(result);

console.log(result);
console.log(values);