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POTrouble when trying to access instances of webcomponents in the dom in Dart?
 

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  1. POTrouble when trying to access instances of webcomponents in the dom in Dart?
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    <p>I have created a webcomponent called "color-item" and instantiated it throug adding its custom element tag in the html. I'we also given the elements id's like this:</p> <pre><code>&lt;color-item id="colorItem1" color_text="LimeGreen" bg_color="LimeGreen" &gt;&lt;/color-item&gt; &lt;color-item id="colorItem2" color_text="green" bg_color="YellowGreen" &gt;&lt;/color-item&gt; </code></pre> <p>The compoenents show up just fine and behave as expected. However, when I try to access those elements (in the main loop) to do some fun things on them with Dart-code I just end up with errors. Here is how I have tried to access them:</p> <pre><code> ColorItem color_Item1 = query("#colorItem1").xtag; ColorItem color_Item2 = query("#colorItem2").xtag; </code></pre> <p>That produces the following error:</p> <pre><code> Breaking on exception: type 'DivElement' is not a subtype of type 'ColorItem' of 'color_Item1'. </code></pre> <p>I'we also tried casting like this:</p> <pre><code> ColorItem color_Item1 = query("#colorItem1").xtag(ColorItem); ColorItem color_Item2 = query("#colorItem2").xtag(ColorItem); </code></pre> <p>That produces a similar error:</p> <pre><code> Exception: type 'DivElement' is not a subtype of type 'ColorItem' of 'color_Item1'. Breaking on exception: Class 'DivElement' has no instance method 'call'. </code></pre> <p>The component itself is defined like this:</p> <pre><code> &lt;!DOCTYPE html&gt; &lt;html&gt; &lt;body&gt; &lt;element name="color-item" constructor="ColorItem" extends="div"&gt; &lt;template&gt; &lt;style scoped&gt; .color-box{ cursor:pointer; padding:20px; margin:10px; margin-left:0px; display:inline-block; width:auto; height:auto; position: relative; font-size: 24px; color:white; background-color:orange; border-radius:24px; box-shadow: 2px 2px 10px rgba(0,0,0,0.2); user-select: none; } &lt;/style&gt; &lt;div class="color-box" style="background-color:{{bg_color}}; color:{{text_color}}" on-click="swapColor()"&gt; Color: &lt;b&gt;{{color_text}}&lt;/b&gt; &lt;/div&gt; &lt;/template&gt; &lt;script type="application/dart" src="ColorItem.dart"&gt;&lt;/script&gt; &lt;/element&gt; &lt;/body&gt; &lt;/html&gt; </code></pre> <p>and the script for the component looks like this:</p> <pre><code> import 'package:web_ui/web_ui.dart'; class ColorItem extends WebComponent { @observable String color_text ="orange"; @observable String bg_color ="orange"; @observable String text_color ="white"; @observable ColorItem next_color_item =null; List&lt;String&gt; colors = new List&lt;String&gt;() ..add("LimeGreen") ..add("green") ..add("yellow") ..add("OrangeRed") ..add("red") ..add("purple") ..add("blue"); int i = 0; String getNextColor(){ i++; i%=colors.length; return colors[i]; } void swapColor(){ String oldColor = bg_color; String nextColor = getNextColor(); bg_color = nextColor; color_text = nextColor; if(next_color_item!=null){ next_color_item.bg_color = oldColor; next_color_item.color_text = oldColor; } } } </code></pre> <p>Any suggestions?</p>
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