如何发出POST请求以按角度保存层次结构中的对象列表 [英] How to make POST requests to save a list of objects in the hierarchical structure in angular

问题描述

我有一个层次结构中的对象列表，这些对象与parentId相关，例如:

I have a list of objects in the hierarchical structure which are related by parentId, for example:

[
  {
    id: 10,
    name: "Parent Unit 1",
    parentId: null, 
    children: 
    [
      {
        id: 11,
        name: "Unit Child 1.1",
        parentId: 10,
        children:
        [
          {
            id: 15,
            name: "Unit Child 1.1.1",
            parentId: 11,
            children: []
        ]   
      }, 
      {
        id: 12,
        name: "Unit Child 1.2",
        parentId: 10,  
        children: []
      }
    ]   
  },
  {
    id: 13,
    name: "Parent Unit 2",
    parentId: null, 
    children: 
    [
      {
        id: 14,
        name: "Unit Child 2.2",
        parentId: 13,
        children: []  
      }
    ]
]

我需要通过调用POST方法六次来通过Web服务一一保存对象.要求是我必须顺序保存它们.我的意思是，当Web服务返回父对象的新ID时，我必须等到保存父单元，然后我才能向Web服务发出另一个POST请求，并为Unit Child对象修改parentID.

I need to save objects one by one through web service by calling POST method six times. The requirement is that I have to save them sequentially. I mean, I have to wait until Parent Unit is saved, when the web service returns new id of the parent object and then I can make another POST request to web service with modified parentId for Unit Child objects.

我使用Observables在我的角度应用程序中制作Web服务.有什么想法我该怎么做?

I use Observables for making web services in my angular app. Any ideas how can I do it?

推荐答案

您可以使用switchMap

这是其工作原理的基本示例

Here's a basic example of how it works

Rx.Observable.of('some_url')
  .switchMap(url => this.http.get(url))

基本上，您会获得第一个ID，将其切换映射以在第二个调用中使用它，等等...

Basically, you get the first id, switchmap it to use it on the 2nd call etc...

在此处了解更多信息: https://www.learnrxjs.io/operators /transformation/switchmap.html

Read more about it here: https://www.learnrxjs.io/operators/transformation/switchmap.html

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