Adding dynamic WebComponent divs

Question

I'm trying to dynamically add a number of divs using Dart. The divs contain a custom web component, and I'm trying to pass in a variable. I want to be able to specify n number of variables, pass them to n number of components, and insert those into an HTML document. What's happening, however, is I'm getting the inserted divs without the variables. I wonder if this is a case of Dart trying to pass something into a an already loaded DOM and therefore doing nothing...? Here's some code:

product_elem.dart:

import 'package:web_ui/web_ui.dart';
import 'dart:html';

class ProductComponent extends WebComponent {
  var productId;
}

product_elem.html:

<!DOCTYPE html>
  <html>
    <body>
      <element name="product-elem" constructor="ProductComponent" extends="div">
        <template>
          <div style="width:335px;margin:10px;">
            <h3>
              {{productId}}
            </h3>
         </div>
      </template>
      <script type="application/dart" src="product_elem.dart"></script>
    </element>
  </body>
</html>

testcase_component.dart:

import 'dart:html';
import 'package:web_ui/web_ui.dart';

var productId;

void main() {
  List myList = new List();
  myList.addAll(["Foo", "Bar", "Baz"]);
  for (var i = 0; i < myList.length; i++) {
    productId = myList[i];
    query('#products').innerHtml += 
      "<div is='product-elem' id='product_elem' product-id='{{productId}}'></div>";
  }
}

testcase_component.html:

<!DOCTYPE html>
<html>
  <head>
    <link rel="import" href="product_elem.html">
  </head>
  <body>
    <div id="products">
      <!-- Insert dynamic divs here -->
    </div>
    <script type="application/dart" src="testcase_component.dart"></script>
    <script src="packages/browser/dart.js"></script>
  </body>
</html>

Pixel Elephant Pixel Elephant · Accepted Answer · 2013-06-17T18:02:28

You can't just add WebComponents like that. WebUI doesn't know that anything was added, so you just end up with a normal div.

Here is the current (slightly messy) way to dynamically add WebComponents:

void main() {
  List myList = new List();
  myList.addAll(["Foo", "Bar", "Baz"]);
  for (var i = 0; i < myList.length; i++) {
    productId = myList[i];
    var product = new ProductComponent(productId);
    product.host = new DivElement();
    var lifecycleCaller = new ComponentItem(product)..create();
    query('#products').append(product.host);
    lifecycleCaller.insert();
  }
}

This way the proper WebUI lifecycles are called.

Also make sure to add a constructor for ProductElem so that productId can be externally set:

class ProductComponent extends WebComponent {
  var productId;

  ProductComponent(this.productId);

}

Adding dynamic WebComponent divs

1 Answers