i'm working with Angular 9 and rxjs 6, and i'm trying to get a list of Nodes :

NodeService.ts

`public getList(): Observable<Nodes[]> { return this.http.get<Nodes[]>(URL); }`

Nodes Entity:

```
export class Nodes {
     public id: number;
     public name: string;
     public site_id: number;
     public site: Site;
}

```

nodes.component.ts:

```
public getAllNodes() {
  this.dataSource.data = [];
  this.nodeService.getList()
    .subscribe(
      nodes => {
        nodes.map(
          (node) => {
            this.siteService.getSiteById(node.site_id).subscribe(site => {
              node.site = site;
            })
          });
        this.dataSource.data = nodes;
        console.log(nodes);
      },
      error => {
        console.log(error);
      },
      () => {
      }
    );
}

```

=> By default, node.site = null, so i use node.site\_id to get the complete "Site" object in the subscribe method.
But i have almost 6000 call to "siteService.getSiteById()" and i have error like: Insufficient resources.

Do you have any better way to do it,

Thank you