title: Params url do not execute get method form server
body: <p>I have very strange problem. 
  I have component <code>ProductListItemsComponent</code>, In <code>ngOnInit</code> I execute the method <code>getCategoryFromServer</code> and <code>getProductList()</code>. This is look like:</p>
  
  <pre><code>ngOnInit() {
    this.productsService.getCategoryFromServer();
    this.getProductList();
  }
  </code></pre>
  
  <p>Method <code>getCategoryFromServer</code> is  in my service  <code>ProductsService</code> :</p>
  
  <pre><code>getCategoryFromServer() {
    this.dataStorageServiceServiceta.getCategory().subscribe((category: CategoryModel[]) =&gt; {
      this.categoryModule = category;
      this.cateogoryChange.next(this.categoryModule.slice())
    })
  }
  </code></pre>
  
  <p>Method <code>getProductList()</code> in  my component and look like this:</p>
  
  <pre><code>getProductList() {
    this.subscription = this.route.params
      .subscribe((params: Params) =&gt; {
        this.categoryName = params['category'];
        this.singleProducts = this.productsService.getListOfProduct(this.categoryName);
      })
  }
  </code></pre>
  
  <p>Problem is because start executing <code>getCategoryFromServer</code> and skip execution, and executed <code>getProductList</code> and after that execute <code>getCategoryFromServer</code>. But I need to first execute <code>getCategoryFromServer</code> and after that <code>getCategoryFromServer</code>.</p>