使用 lodash 将 Typescript 中的项目分组 [英] Group items in Typescript with lodash
本文介绍了使用 lodash 将 Typescript 中的项目分组的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我需要按日期对一组对象进行分组:
I need to group a collection of objects by date:
var meetings =
[
{date:"2001-01-01 13:00", place:"park"},
{date:"2001-01-01 14:00", place:"school"},
{date:"2001-01-02 11:00", place:"house"}
];
因此它变为:
var groupedMeetings =
[
{
day:"2001-01-01",
meetings:
[
{date:"2001-01-01 13:00", place:"park"},
{date:"2001-01-01 14:00", place:"school"}
]
},
{
day:"2001-01-02",
meetings:
[
{date:"2001-01-02 11:00", place:"house"}
]
}
]
我能够将它们与_.groupBy和_.map分组
I was able to group them with _.groupBy and _.map
var g = _.groupBy(meetings, function(i){return getDatePart(i.date);});
var groupedMeetings = _.map(g, function(items,key){return {day:key, meetings:items};});
首先,我宣布了自己的课程:
First, I declared my classes:
class Meeting
{
date: Date,
place: Meeting[]
}
class GroupedMeeting
{
constructor(private day: Date, private meetings: Meeting[]) {}
}
现在我不知道要使用groupBy的哪个重载?以及如何将其映射到分组项目列表?
Now I dont know which overload of groupBy to use? And how to map it to list of grouped items?
var grouped: _.Dictionary<Meeting[]> = _.groupBy(meetings, (i: Meeting) => { return this.getDatePart(i.date); });
var groupedMeetings : GroupedMeeting[] = _.map(grouped, (items: Meeting[], key: Date) => { return new GroupedMeeting (key, items); });
推荐答案
您可以使用 _.groupBy()
方法并添加一个回调,该回调返回您需要将其分组的值,该值是日期的年,月,日部分.然后,您可以使用 _.map()
来设置所需的值.
You can make use of the _.groupBy()
method and add a callback that returns the value you need to group it with, which is the year, month, day part of the date. You can then set the values needed by using _.map()
.
下面的示例使用ES6:
The example below uses ES6:
var meetings =
[
{date:"2001-01-01 13:00", place:"park"},
{date:"2001-01-01 14:00", place:"school"},
{date:"2001-01-02 11:00", place:"house"}
];
var result = _(meetings)
.groupBy(meeting => meeting.date.split(' ').shift())
.map((meetings, day) => ({ day, meetings }))
.value();
document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');
<script src="https://cdn.jsdelivr.net/lodash/4.11.2/lodash.min.js"></script>
这是ES5版本:
var meetings =
[
{date:"2001-01-01 13:00", place:"park"},
{date:"2001-01-01 14:00", place:"school"},
{date:"2001-01-02 11:00", place:"house"}
];
var result = _(meetings)
.groupBy(function(meeting) { return meeting.date.split(' ').shift(); })
.map(function(meetings, day) { return { day: day, meetings: meetings }; })
.value();
document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');
<script src="https://cdn.jsdelivr.net/lodash/4.11.2/lodash.min.js"></script>
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