递归http-api调用后的消息订阅者 [英] Message Subscribers after recursive http-api calls

问题描述

我想获取节点列表以创建所述节点对象的数组以显示层次结构.基于的数据/结构如下所示:

I want to fetch a list of nodes to create an array of said node objects in order to display an hierarchy. The based data/structure looks like this:

ROOT (ID=1)
|--NODE (ID=2)
|  └--NODE (ID=4)
|     └--NODE (ID=11)
└--NODE (ID=3)
   |--NODE (ID=5)
   |--NODE (ID=6)
   |--NODE (ID=7)
   └--NODE (ID=8)
      |--NODE (ID=9)
      └--NODE (ID=10)  

您有一个根节点，其中的子节点也包含子节点.包括ROOT节点在内，树中包含3个阶段.我创建了一个REST-API，该API返回给定节点内的子级.我还尝试在REST结构中对该层次结构进行建模，因此调用看起来像这样:

You have a Root Node, with child nodes which also contain childs. Inclucing the ROOT node, there are 3 stages in the tree. I created an REST-API which returns the children inside the given node. I also tried to model this hierarchy inside my REST structure, so the calls look like this:

TYPE        PATH                      RESULT CHILD IDs
GET         /1/nodes                  2, 3
GET         /1/nodes/2/nodes          4
GET         /1/nodes/3/nodes          5, 6, 7, 8
GET         /1/nodes/3/nodes/8/nodes  9, 10 

为了构建树，我尝试使用递归模式，如下所示:

In order to build a tree I tried to use a recursive pattern, something like this:

    this.subject.next(this.getNodes('/1/nodes'); /*root-uri*/

    getNodes(uri) {
      const nodeList: Node[] = [];
      http.get(path).subscribe(data => {
        for(const obj of data.json()) {
            let node = new Node();
            //map data to Node e.g node.is = data.id

            //get the children with the nested call
            node.children = getNodes(uri + '/' + node.id + '/nodes'); 
            nodeList.push(node);
        }
    }
    return nodeList;
}  

所以我的问题是:
如何通过递归http调用创建节点对象数组并将消息发送给订阅者，以便订阅者仅接收正确结构的完整节点数组

编辑

这是节点模型的样子

export class Node {
  uuid: string;
  label: string;
  parentID: string;
  version: number;
  addableFlag: boolean;
  sectionFlag: boolean;
  children: Node[];
}

推荐答案

您将需要在 subscribe()范围内设置 this.subject 值.因此，在设置值之前，它具有正确结构的完整列表.

You will need to set the this.subject value with in the subscribe() scope. So that way it has a complete list in correct structure before setting the values.

this.getChildren('/1/nodes'); /*root-uri*/

getNodes(uri) {
    const nodeList: Node[] = [];
    http.get(path).subscribe(data => {
        for (const obj of data.json()) {
          let node = new Node();
          //map data to Node e.g node.is = data.id

          //get the children with the nested call
          node.children = getNodes(uri + '/' + node.id + '/nodes');
          nodeList.push(node);
        }
        this.subject.next(nodeList); /*root-uri*/
    }
      // Return would send empty data as this line get executed before data arrives
      // return nodeList;
}

这将起作用，因为它会在有数据时设置主题的值.

That will work as it sets the value of the subject when it has data.

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