使用 Observables 合并子数组 [英] Merge subarrays using Observables

问题描述

我有这个数据结构:

[{
    id : 1,
    name : "Item 1",
    subItems : [{
            id : 1,
            name : "SubItem 1"
        },{
            id : 2,
            name : "SubItem 2"
        }
    ]
}, {
    id : 2,
    name : "Item 2",
    subItems : [{
            id : 3,
            name : "SubItem 3"
        }, {
            id : 4,
            name : "SubItem 4"
        }
    ]
}]

我对网络服务进行以下调用以获取项目:this.dataService.get("items")

I make the following call to a web service to get the items: this.dataService.get("items")

返回的是一个 Observable.我可以使用哪些 Observable 运算符来仅获取子项的串联列表?我想以这样的方式结束:

Returned is an Observable<Item[]>. What Observable operators can I use to only get a concatenated list of SubItems? I would like to end up with something like this:

[{
    id : 1,
    name : "SubItem 1"
}, {
    id : 2,
    name : "SubItem 2"
},
{
    id : 3,
    name : "SubItem 3"
}, {
    id : 4,
    name : "SubItem 4"
}]

我应该使用 flatMap 或 concat 之类的东西吗?

Should I use something like flatMap or concat?

推荐答案

假设它是一个错字并且第二个元素也有 subItems(而不是 searchProfiles)，您不需要 flatMap 或任何类似的东西，您可以使用 js 数组运算符在普通地图中完成它:

Provided it is a typo and the second element has subItems as well (and not searchProfiles), you don't need flatMap or any thing of the sort, you can do it in a plain map using js array operators:

var transformed = [].concat(...result.map(item => item.subItems));

或者你的情况

httpResult$.map(result => [].concat(...result.map(item => item.subItems))

如果故意使用不同的键，您的内部映射将需要更多的逻辑，但映射将完全相同

if the use of different keys is deliberate, your internal map will require a bit more logic but the mapping will be quite the same

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