title: Assign array of JSON objects to array of interface Angular/Typescript
body: <p>Currently, this works and doesn't give my error while running but my text editor is giving me an error that says property 'categories' does not exist on type 'CategoryInterface[]' (on the line where response.categories is assigned to variable) so I'm not sure if I'm doing things right. </p>
  
  <pre><code>    public categories: CategoryInterface[];
  
            .subscribe((response: CategoryInterface[]) =&gt; {
            this.categories = response.categories;
            console.log(this.categories);
        });
  </code></pre>
  
  <p>My backend returns this:</p>
  
  <pre><code>{
  "categories": [
      {
          "categoryId": 1,
          "name": "Important",
          "description": "This category is important.",
          "order": 1,
          "createdBy": null,
          "createdAt": "2017-11-25 12:09:04",
          "updatedBy": null,
          "updatedAt": "2018-01-17 23:53:25",
          "categoryBoards": [
              {
                  "categoryBoardId": 1,
                  "categoryId": 1,
                  "name": "Announcements",
                  "description": null,
                  "order": 2,
                  "createdBy": null,
                  "createdAt": "2017-11-25 12:09:49",
                  "updatedBy": null,
                  "updatedAt": "2018-01-18 00:09:02"
              },
              {
                  "categoryBoardId": 23,
                  "categoryId": 1,
                  "name": "Rules",
                  "description": null,
                  "order": 1,
                  "createdBy": null,
                  "createdAt": "2018-01-18 00:08:57",
                  "updatedBy": null,
                  "updatedAt": "2018-01-19 00:05:51"
              }
          ]
      }
  ]
  </code></pre>
  
  <p>}</p>