是否有可能对过滤器进行“过滤"按打字稿中的值映射? [英] Is it possible to "filter" a Map by value in Typescript?

问题描述

我正在寻找一种通过值而不是键来过滤地图的方法.我的Angular应用程序中有一个数据模型如下:

I am looking for a way to filter a map by value instead of key. I have a data set that is modeled as follows in my Angular application:

{
  "85d55e6b-f4bf-47bb-a988-78fdb9650ef0": {
    is_deleted: false,
    public_email: "[e-mail]",
    id: "85d55e6b-f4bf-47bb-a988-78fdb9650ef0",
    modified_at: "2017-09-26T15:35:06.853492Z",
    social_url: "https://facebook.com/jamesbond007",
    event_id: "213b01de-da9e-4d19-8e9c-c0dae63e019c",
    visitor_id: "c3c232ff-1381-4776-a7f2-46c177ecde1c",
  },
}

这些条目上的键与条目值上的id字段相同.

The keys on these entries are the same as the id field on the entries values.

给出几个这样的条目，我想过滤并返回一个new Map()，该new Map()仅包含具有给定event_id的那些条目.如果这是一个数组，我将执行以下操作:

Given several of these entries, I would like to filter and return a new Map() that contains only those entries with a given event_id. Were this an array I would just do the following:

function example(eventId: string): Event[] {
  return array.filter((item: Event) => item.event_id === eventId);
}

本质上，我试图复制Array.prototype.map()的功能-仅在Map而不是Array上.

Essentially, I am attempting to replicate the functionality of Array.prototype.map() - just on a Map instead of an Array.

我愿意使用Lodash，因为它可以帮助我以更简洁的方式实现此目的，因为它已经在我的项目中提供了.

I am willing to use Lodash if it will help achieve this in a more succinct way as it is already available in my project.

推荐答案

是

Array.from(map.values()).filter((item: Event) => item.event_id === eventId);

或者对于TypeScript downlevelIteration 选项

Or for TypeScript downlevelIteration option,

[...map.values()].filter((item: Event) => item.event_id === eventId);

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