按多个值分组Undercore.JS，但保留键和值

Group by multiple values Underscore.JS but keep the keys and values

本文关键字：JS 保留 键和值 Undercore      更新时间：2023-09-26

我正在尝试用对象对以下数组进行分组：

[ { user_id: 301, alert_id: 199, deal_id: 32243 },
  { user_id: 301, alert_id: 200, deal_id: 32243 },
  { user_id: 301, alert_id: 200, deal_id: 107293 },
  { user_id: 301, alert_id: 200, deal_id: 277470 } ]

正如您所看到的，它包含user_id和alert_id组合，我喜欢将它们分组。所以我想要以下数组：

[ { user_id: 301, alert_id: 199, deals: [32243] },
  { user_id: 301, alert_id: 200, deals: [32243,107293,277470]}]

有人知道解决这个问题的办法吗？使用下划线的GroupBy，我可以根据一个键对值进行分组。但我需要根据user_id和alert_id的组合对它们进行分组，正如您所看到的。

我看了undercore.nest，但问题是它创建了自己的密钥。

将groupBy与使用user_id和alert_id创建复合密钥的函数一起使用。然后绘制分组以获得您想要的：

    var list = [ { user_id: 301, alert_id: 199, deal_id: 32243 },
      { user_id: 301, alert_id: 200, deal_id: 32243 },
      { user_id: 301, alert_id: 200, deal_id: 107293 },
      { user_id: 301, alert_id: 200, deal_id: 277470 } ];
    var groups = _.groupBy(list, function(value){
        return value.user_id + '#' + value.alert_id;
    });
    var data = _.map(groups, function(group){
        return {
            user_id: group[0].user_id,
            alert_id: group[0].alert_id,
            deals: _.pluck(group, 'deal_id')
        }
    });

我想贡献一个整洁的打字脚本ES6组。
我真的不知道如何加强返回值的键入。这里需要一些技巧，但这对我来说相当有效

/**
 * group the supplied list by a set of keys.
 * @param list the list of items to group.
 * @param children the key for the array of child items.
 * @param components the components to group by.
 */
groupByMultipleFields<T, K extends keyof T>(
    list: T[],
    children: string,
    ...components: K[]): any[] {
    var grouping = [...list.reduce((r, o) => {
        const key = components.map(_ => `${o[_]}`).join(" :: ");
        var keyed = r.get(key) || components.reduce((x, y) => { x[y] = o[y]; return x; }, <T>{});
        keyed[children] = keyed[children] || [];
        keyed[children].push(o);
        return r.set(key, keyed);
    }, new Map).values()];
    return grouping;
}

您需要打开typescript编译器选项"downlevelIteration": true，以允许new Map迭代并返回values()。

对于某些特定的任务，我必须为其保护密钥和值所以我制作了这个变体（使用干净的js）：

/**
 * Group your items in array by multiple keys!
 *
 * @param collection
 * @param retrieveFunctions
 * @param compareFunctions
 * @returns {Array}
 */
function groupify(
    collection,
    retrieveFunctions = {attribute: value => value},
    compareFunctions = {attribute: (groupValue, value) => groupValue === value}
) {
    let groups = [];
    let keyValues = {};
    collection.forEach(item => {
        for (let attribute in retrieveFunctions) {
            keyValues[attribute] = retrieveFunctions.hasOwnProperty(attribute) ? retrieveFunctions[attribute](item[attribute]) : undefined;
        }
        let group = groups.find(group => {
            for (let key in retrieveFunctions) {
                if (!group && !group.keys[key]) {
                    return false;
                }
                if (compareFunctions[key] instanceof Function) {
                    if (!compareFunctions[key](group.keys[key], keyValues[key])) {
                        return false;
                    }
                } else if (group.keys[key] !== keyValues[key]) {
                    return false;
                }
            }
            return true;
        });
        !group ? groups.push({keys: keyValues, items: [item]}) : group.items.push(item);
        keyValues = {};
    });
    return groups;
}

以下是要点链接：groupify.js

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