It appears that my Polymer Dart custom elements that were once working now stopped firing. Dartium displays in localhost the h1 tag but not my custom elements.
The only Dart Editor error/warning I get is:
"(from html5lib) Unexpected start tag (link). Expected DOCTYPE. See http://goo.gl/5HPeuP#polymer_40 for details."
This warning message appears on every
<link rel="import" href="packages/polymer/polymer.html">
but as best I can see this is a known issue which should not impede application execution.
My troubleshooting efforts to date include:
- Running pub cache repair from command line
- Manually deleting package cache directory and running pub get again.
- Downloading and running polymer-and-dart-codelab-master.zip (I get the same behavior)
How can I diagnose this issue?
Pubspec.yaml contents:
name: mpower
description: Sample app built with the polymer.dart package
environment:
sdk: '>=1.2.0 <2.0.0'
dependencies:
polymer: '>=0.15.1 <0.16.0'
dev_dependencies:
unittest: '>=0.10.0 <0.11.0'
transformers:
- polymer:
entry_points:
- web/index.html
Index.html Contents:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Mosaic mPower</title>
<link rel="import" href="est_list.html">
<link rel="stylesheet" href="app.css">
</head>
<body>
<h1>Mosaic mPower</h1>
<est-list></est-list>
<script type="application/dart">export 'package:polymer/init.dart';</script>
</body>
</html>
est-list.html
<link rel="import" href="packages/polymer/polymer.html">
<link rel="import" href="est_form.html">
<link rel="import" href="est_element.html">
<polymer-element name="est-list">
<template>
<style>
select {
margin-bottom: 30px;
display: inline;
padding: 6px 12px;
font-size: 14px;
line-height: 1.42857143;
color: #555;
background-color: #fff;
background-image: none;
border: 1px solid #ccc;
border-radius: 2px;
-webkit-box-shadow: inset 0 1px 1px rgba(0,0,0,.075);
box-shadow: inset 0 1px 1px rgba(0,0,0,.075);
-webkit-transition: border-color ease-in-out .15s,box-shadow ease-in-out .15s;
transition: border-color ease-in-out .15s,box-shadow ease-in-out .15s;
}
</style>
<div>
<label>Filter: </label>
<select value="{{filterValue}}" on-change="{{filter}}">
<option template repeat="{{filter in filters}}">
{{filter}}
</option>
</select>
</div>
<div on-estvalidated="{{addEst}}"
on-formnotneeded="{{resetForm}}">
<est-form est="{{newEst}}"></est-form>
</div>
<div on-deleteest="{{deleteEst}}"
on-levelchanged="{{filter}}">
<template repeat="{{est in filteredEsts}}">
<est-element est="{{est}}"></est-element>
</template>
</div>
</template>
<script type="application/dart" src="est_list.dart"></script>
est-list.dart
import 'package:polymer/polymer.dart';
import 'model.dart' show Est;
import 'dart:html' show Event, Node;
/*
* Class to represent a collectionon-est of Est objects.
*/
#CustomTag('est-list')
class EstList extends PolymerElement {
static const ALL = "all";
/*
* Field for a new Est object.
*/
#observable Est newEst = new Est();
/*
* Collection of ests. The source of truth for all ests in this app.
*/
#observable List<Est> ests = toObservable([]);
/*
* Sets the new est form to default to the intermediate level.
*/
String get defaultCustomer => Est.CUSTOMERS[0];
/*
* List of filter values. Includes the levels defined in the model, as well
* as a filter to return all ests.
*/
final List<String> filters = [ALL]..addAll(Est.CUSTOMERS);
/*
* String that stores the value used to filter ests.
*/
#observable String filterValue = ALL;
/*
* The list of filtered ests.
*/
#observable List<Est> filteredEsts = toObservable([]);
/*
* Named constructor. Sets initial value of filtered ests and sets
* the new est's customer to the default.
*/
EstList.created() : super.created() {
filteredEsts = ests;
newEst.customer = defaultCustomer;
}
/*
* Replaces the existing new Est, causing the new est form to reset.
*/
resetForm() {
newEst = new Est();
newEst.customer = defaultCustomer;
}
/*
* Adds a est to the ests list and resets the new est form. This
* triggers estsChanged().
*/
addEst(Event e, var detail, Node sender) {
e.preventDefault();
ests.add(detail['est']);
resetForm();
}
/*
* Removes a est from the ests list. This triggers estsChanged().
*/
deleteEst(Event e, var detail, Node sender) {
var est = detail['est'];
ests.remove(est);
}
/*
* Calculates the ests to display when using a filter.
*/
filter() {
if (filterValue == ALL) {
filteredEsts = ests;
return;
}
filteredEsts = ests.where((est) {
return est.customer == filterValue;
}).toList();
}
/*
* Refreshes the filtered ests list every time the ests list changes.
*/
estsChanged() {
filter();
}
}
As mentioned in the comment,
this is caused by an expired Dartium.
Sadly it doesn't show a message to tell about it.
Star this open issue http://dartbug.com/18560 for updates.
Related
When I have a reference to an element that was produced by a <template>, in Polymer.js such elements have an attribute templateInstance that provides a references to its template like it's used here:
https://github.com/PolymerLabs/polymer-selector/blob/master/polymer-selector.html#L286
Polymer >= 1.0.0
#reflectable
void someClickHandler(dom.Event event, [_]) {
// for native events (like on-click)
var model = new DomRepeatModel.fromEvent(event);
// or for custom events (like on-tap, works also for native events)
var model = new DomRepeatModel.fromEvent(convertToJs(event));
var value = model.jsElement['items'];
// or
var value = model.jsElement[$['mylist'].attributes['as']];
// if you used the `as="somename"`
// in your <core-list> or <template is="dom-repeat">
}
There is an open issue related to custom events: https://github.com/dart-lang/polymer-dart/issues/624
Polymer <= 0.16.0
EDIT
The example below needs only this 3 lines, the other code is just for demonstration purposes
import 'package:template_binding/template_binding.dart' as tb;
tb.TemplateInstance ti = tb.nodeBind(e.target).templateInstance;
var value = ti.model.value as Inner;
EDIT END
This functionality was added recently (see https://code.google.com/p/dart/issues/detail?id=17462)
I created an example to test how it works:
index.html
<!DOCTYPE html>
<html>
<head>
<title>nested-repeat</title>
<!-- <script src="packages/web_components/platform.js"></script>
not necessary anymore with Polymer >= 0.14.0 -->
<script src="packages/web_components/dart_support.js"></script>
<link rel="import" href="nested_templates.html">
</head>
<body>
<nested-templates></nested-templates>
<script type="application/dart">export 'package:polymer/init.dart';</script>
</body>
</html>
nested_templates.html
<link rel="import" href="packages/polymer/polymer.html">
<polymer-element name="nested-templates">
<template>
<style>
:host { display: block; height: 100%; }
ul { margin: 0; padding: 0; }
li { font-size: 0.85rem; padding-left: 0.75rem; }
li:hover { background: lightgrey; cursor: pointer; }
li.selected { color: red; }
</style>
<div>
<template repeat="{{o in outer}}">
<strong>{{o.name}}</strong>
<ul>
<template repeat="{{i in o.inner}}">
<li id="{{i.name}}" on-click="{{innerClickHandler}}" template-value='{{i}}'>{{i.name}}</li>
</template>
</ul>
</template>
</div>
</template>
<script type="application/dart" src="nested_templates.dart"></script>
</polymer-element>
nested_templates.dart
import 'dart:html' as dom;
import 'package:polymer/polymer.dart';
import 'package:template_binding/template_binding.dart' as tb;
#CustomTag('nested-templates')
class NestedTemplates extends PolymerElement {
NestedTemplates.created() : super.created();
#observable List<Outer> outer = toObservable([new Outer('o1', toObservable(
[new Inner('a'), new Inner('b')])), new Outer('o2', toObservable([new Inner(
'c'), new Inner('d')]))], deep: true);
void innerClickHandler(dom.Event e) {
shadowRoot.querySelectorAll('li.selected').forEach((e) => (e as
dom.HtmlElement).classes.remove('selected'));
(e.target as dom.HtmlElement).classes.add('selected');
tb.TemplateInstance ti = tb.nodeBind(e.target).templateInstance; // get access to the TemplateInstance of the element
// TemplateInstance provides access to the model and the actual value
var value = ti.model.value as Inner;
print('name: ${value.name}'); // works
print('equals: ${value == (e.target as dom.HtmlElement).attributes['template-value']}'); // prints "false"
print(
'${(e.target as dom.HtmlElement).attributes['template-value']}'); // prints "Instance of 'Inner'"
// shows that the attribute only has the result of 'toString()' but not the actual value of type 'Inner'
print(
'${(e.target as dom.HtmlElement).attributes['template-value'].runtimeType}'); // prints "String"
}
}
class Inner extends Observable {
#observable String name;
Inner(this.name);
}
class Outer extends Observable {
#observable String name;
List<Inner> inner;
Outer(this.name, this.inner);
}
I use dart-polymer package to create custom elements. I have noticed that there is some blinking during of page with the custom elements loading. This effect also is visible for the very simple ClickCounter app. Is there any way to avoid this vexing blinking?
The issue is good described in Wikipedia http://en.wikipedia.org/wiki/Flash_of_unstyled_content
The suggested solution from http://www.polymer-project.org/docs/polymer/styling.html#fouc-prevention does not work for the simple application (polymer: '0.10.0-pre.2')..
<html>
<head>
<title>Click Counter</title>
<!-- import the click-counter -->
<link rel="import" href="packages/polymer/polymer.html">
<link rel="import" href="clickcounter.html">
<script type="application/dart">export 'package:polymer/init.dart';</script>
<script src="packages/browser/dart.js"></script>
</head>
<body unresolved>
<h1>CC</h1>
<p>Hello world from Dart!</p>
<div id="sample_container_id">
<click-counter count="5"></click-counter>
</div>
</body>
</html>
<polymer-element name="click-counter" attributes="count">
<template>
<style>
div {
font-size: 24pt;
text-align: center;
margin-top: 140px;
}
button {
font-size: 24pt;
margin-bottom: 20px;
}
</style>
<div>
<button on-click="{{increment}}">Click me</button><br>
<span>(click count: {{count}})</span>
</div>
</template>
<script type="application/dart" src="clickcounter.dart"></script>
</polymer-element>
import 'package:polymer/polymer.dart';
/**
* A Polymer click counter element.
*/
#CustomTag('click-counter')
class ClickCounter extends PolymerElement {
#published int count = 0;
ClickCounter.created() : super.created() {
}
void increment() {
count++;
}
}
see also the created issue in code.google.com https://code.google.com/p/dart/issues/detail?id=17498
Polymer 0.9.5
The class names to use are polymer-veiled (hidden) and polymer-unveil (during unveil transition)
If it is different than in Polymer.js it is probably subject of change but as of PolymerDart 0.9.0 it should work.
The relevant code is in packages/polymer/src/boot.dart.
Polymer 0.10.0
Polymer 0.10.0-pre.1 uses already the unresolved attribute like explained here
Polymer - Styling reference - FOUC prevention
You need to add a version constraint in pubspec.yaml to get the development version like
polymer: ">=0.10.0-pre.1"
I'm trying to style distributed nodes in Dart Polymer with no luck. I'm using the example at:
http://www.polymer-project.org/articles/styling-elements.html#style-distributed
as a starting point. However, I can't even get that working once ported to Dart. Here is my code:
<polymer-element name="test-element">
<template>
<style>
content[select="p"]::content * { /* anything distributed here */
font-weight: bold;
}
/* #polyfill p:first-child */
::content p:first-child {
color: red;
}
/* #polyfill footer > p */
::content footer > p {
color: green;
}
/* #polyfill :host > p */
::content > p { /* scope relative selector */
color: blue;
}
</style>
<content select="p"></content>
<content></content>
</template>
<script type="application/dart" src="testelement.dart"></script>
</polymer-element>
.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Sample app</title>
<link rel="stylesheet" href="testpolymer.css">
<!-- import the test-element -->
<link rel="import" href="testelement.html">
<script type="application/dart">export 'package:polymer/init.dart';</script>
<script src="packages/browser/dart.js"></script>
</head>
<body>
<h1>TestPolymer</h1>
<p>Hello world from Dart!</p>
<test-element>
<p>I'm red and bold</p>
<p>I'm blue and bold</p>
<footer>
<p>I'm also red</p>
<p>I'm green</p>
<span>I'm black</span>
</footer>
</test-element>
</body>
</html>
The output has no styling applied and is just black text for everything. Any ideas what I'm doing wrong?
polymer-elements polymer-flex-layout / polymer-flex-layout.css still use
::-webkit-distributed(p) {
color: red;
}
which also works in my recent version of Dartium.
I have no idea when the new selectors take effect.
Other polymer-elements that make use of this selector but have recently switched to ::content
polymer-ui-field
polymer-ui-menu-item
polymer-ui-nav-arrow
polymer-ui-pages
polymer-ui-sidebar
polymer-ui-toolbar
You can browse the history to find the previous webkit-distributed selector examples.
I guess they use Chromium which may be a little ahead of Dartium.
I am trying to change the default web application that uses the polymer library so that the polymer element is created and added to the DOM from DART code rather than including in the HTML. I have succeeded in adding the element to the DOM, but my observable variable are not being updated on the DOM. The events are being fired, and the values are changing. I have got the DOM to update using Observable.dirtyCheck(), however, this is apparently expensive, so am trying to figure out how to get polymer to update dom without dirtyCheck().
So, In short, how to I get rid of Observable.dirtyCheck()???
dynamiccreate.dart
library dynamiccreate;
import 'dart:html';
import 'package:polymer/polymer.dart';
main() {
initPolymer();
//create click-counter element at runtime from DART, not HTML
var NewElement = new Element.tag('click-counter');
NewElement.setAttribute("count", "5");
//Add to DOM
querySelector('#sample_container_id').children.add(NewElement);
}
dynamiccreate.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Sample app</title>
<link rel="stylesheet" href="dynamiccreate.css">
<!-- import the click-counter -->
<link rel="import" href="clickcounter.html">
<!-- <script type="application/dart">export 'package:polymer/init.dart';</script> -->
<script src="packages/browser/dart.js"></script>
</head>
<body>
<h1>DynamicCreate</h1>
<p>Hello world from Dart!</p>
<div id="sample_container_id">
<!-- <click-counter count="5"></click-counter> -->
</div>
<script src="dynamiccreate.dart" type="application/dart"></script>
</body>
</html>
clickcounter.dart
import 'package:polymer/polymer.dart';
/**
* A Polymer click counter element.
*/
#CustomTag('click-counter')
class ClickCounter extends PolymerElement {
#published int count = 0;
ClickCounter.created() : super.created() {
}
//increment gets called when dynamically adding object at runtime
//But does not update count on DOM
void increment() {
count++;
//Have to add this to update count in DOM
Observable.dirtyCheck(); //<<<---How do I get rid of this???
}
}
clickcounter.html
<polymer-element name="click-counter" attributes="count">
<template>
<style>
div {
font-size: 24pt;
text-align: center;
margin-top: 140px;
}
button {
font-size: 24pt;
margin-bottom: 20px;
}
</style>
<div>
<button on-click="{{increment}}">Click me</button><br>
<span>(click count: {{count}})</span>
</div>
</template>
<script type="application/dart" src="clickcounter.dart"></script>
</polymer-element>
Change your dynamiccreate.dart file to look like this, and the counter starts incrementing in the UI:
library dynamiccreate;
import 'dart:html';
import 'package:polymer/polymer.dart';
main() {
initPolymer().run(() {
var newElement = new Element.tag('click-counter');
newElement.setAttribute("count", "15");
querySelector('#sample_container_id').children.add(newElement);
});
}
Nit: name your variable newElement, not NewElement. Fixed here.
I'm trying to style a custom element tag, and can't seem to do it from within the element's <style> tag, or at least I don't know what selector to use. I've tried the custom element's tag name and template, but neither work.
<polymer-element name="my-test" constructor="MyTest">
<template>
<style>
my-test {
border: solid 1px #888; /* doesn't work */
}
.title {
color: blue; /* works */
}
</style>
<div class="title">{{ title }}</div>
</template>
I'm using polymer.dart, so there may be some lag in its implementation, but I'd like to know how it should work in polymer.js.
I think what you want is the #hostcss selector.
http://www.html5rocks.com/en/tutorials/webcomponents/shadowdom-201/#toc-style-host
As mentioned in another answer, to style the host of the shadow DOM, use #host selector. In the case of a custom element, the host of the custom element is itself.
Here is an example of how to style the host element, or the custom element itself, from within a custom element's <style> tag.
<!DOCTYPE html>
<html>
<head>
<title>index</title>
<script src="packages/polymer/boot.js"></script>
</head>
<body>
<polymer-element name="my-element">
<template>
<style>
#host {
my-element {
display: block;
border: 1px solid black;
}
}
p {
color: red;
}
#message {
color: pink;
}
.important {
color: green;
}
</style>
<p>Inside element, should be red</p>
<div id="message">
The message should be pink
</div>
<div class="important">
Important is green
</div>
<div>
<content></content>
</div>
</template>
<script type="application/dart" src="index.dart"></script>
</polymer-element>
<p>outside of element, should be black</p>
<div id="message">
The outside message should be black
</div>
<div class="important">
Outside important is black
</div>
<my-element>Hello from content</my-element>
<!-- If the script is just an empty main, it's OK to include inline. -->
<!-- Otherwise, put the app into a separate .dart file. -->
<script type="application/dart">main() {}</script>
</body>
</html>
Notice the #host block in the style:
#host {
my-element {
display: block;
border: 1px solid black;
}
}
Because this particular custom element does not extend any element, it does not default to a block.
Here is what it looks like when styled: