I started with the generating click-counter example. I made the click-counter into a library which I then imported into my main file. The click-counter component can be added manually by putting the appropriate HTML into the web page before running the program. However, I've been unable to find a way to dynamically add the click-counter web component to a div. My attempts have either ended in "Aw, snap!" errors or simply with nothing happening.
The click-counter (xclickcounter.dart):
library clickcounter;
import 'package:web_ui/web_ui.dart';
class CounterComponent extends WebComponent {
int count = 0;
void increment() {
count++;
}
}
The main HTML:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Sample app</title>
<link rel="stylesheet" href="test1.css">
<!-- import the click-counter -->
<link rel="components" href="xclickcounter.html">
</head>
<body>
<h1>Test1</h1>
<p>Hello world from Dart!</p>
<div id="sample_container_id">
<div is="x-click-counter" id="click_counter" count="{{startingCount}}"></div>
</div>
<script type="application/dart" src="test1.dart"></script>
<script src="packages/browser/dart.js"></script>
</body>
</html>
main file:
import 'dart:html';
import 'package:web_ui/web_ui.dart';
import 'xclickcounter.dart';
// initial value for click-counter
int startingCount = 5;
void main() {
// no error for adding an empty button
var button = new ButtonElement();
query('#sample_container_id').append(button);
// doesn't work (gives "Aw, snap!" in Dartium)
query('#sample_container_id').append(new CounterComponent());
// Nothing happens with this code. Nothing appears.
// But I promise this same thing was giving Aw, Snap
// for a very similar program
final newComponentHtml = '<div is="x-click-counter"></div>';
query('#sample_container_id').appendHtml(newComponentHtml);
}
I tried added an empty constructor to click-counter but it still crashes.
I had the same issue.
See the example (not mine) at https://github.com/dart-lang/web-ui/blob/master/test/data/input/component_created_in_code_test.html and let me know if it works for you.
TL;DR:
void main() {
var element = query('#sample_container_id');
appendComponentToElement(element, new CounterComponent() );
}
void appendComponentToElement(Element element, WebComponent component) {
component.host = new DivElement();
var lifecycleCaller = new ComponentItem(component)..create();
element.append(component.host);
lifecycleCaller.insert();
}
There's more info at my web-ui#dartlang.org post: https://groups.google.com/a/dartlang.org/d/topic/web-ui/hACXh69UqG4/discussion
Hope that helps.
Related
I have a custom element which toggles hidden states of a span and an input element when clicked so that the user perceives that the span is replaced by the input each time he clicks it.
I want the input to toggle back to hidden state and span to visible state when the input loses focus.
However, once the input is revealed and given the focus, exiting the field (e.g., by clicking outside), the blur handler method is not triggered the first time. On repeating the process the second time, the blur is triggered. For the method to fire, one has to enter the field twice, each time.
How to avoid the need for entering into the input field twice to trigger the on-blur event?
I include my code.
index.html
<!DOCTYPE html>
<html>
<head lang="en">
<link rel="import" href="packages/polymer/polymer.html">
<link rel="import" href="toggle_el.html">
<meta charset="UTF-8">
<title></title>
</head>
<body>
<toggle-el></toggle-el>
<script type="application/dart" src='main.dart'></script>
</body>
</html>
I am initializing polymer from the main.dart
import 'package:polymer/polymer.dart';
main() {
initPolymer();
}
Custom Element html file: toggle_el.html
<link rel="import" href="packages/polymer/polymer.html">
<polymer-element name="toggle-el">
<template>
<span hidden?="{{editMode}}"
on-click="{{switchEdit}}" id="name">{{name}}</span>
<input id="nmInput" hidden?="{{!editMode}}"
on-blur="{{switchEdit}}" type="text"
value="{{name}}"/>
</template>
<script type="application/dart" src="toggle_el.dart"></script>
</polymer-element>
Custom Element dart file: toggle_el.dart
import 'package:polymer/polymer.dart';
import 'dart:html';
#CustomTag('toggle-el')
class toggleElement extends PolymerElement {
#observable String name = 'Dartgnan';
#observable bool editMode = false;
toggleElement.created() : super.created();
#override ready();
void switchEdit(Event ev, var detail, Node sender) {
editMode = !editMode;
print('edit mode is now ${editMode ? 'on' : 'off'}');
if (editMode) {
InputElement el = $['nmInput'];
el.focus();
el.selectionStart = 0;
el.selectionEnd = 999;
}
}
}
Just change el.focus(); to new Future(() => el.focus());.
This way you delay focus a bit and allow the InputElement to get unhidden before focus() is called.
Since polymer-body has been removed, we need to use an auto-binded template to use polymer binding features outside of a PolymerElement:
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Sample app</title>
<script src="packages/web_components/platform.js"></script>
<script src="packages/web_components/dart_support.js"></script>
<link rel="import" href="packages/polymer/polymer.html">
<script src="packages/browser/dart.js"></script>
</head>
<body>
<template is="auto-binding-dart">
<div>Say something: <input value="{{value}}"></div>
<div>You said: {{value}}</div>
<button id="mybutton" on-tap="{{buttonTap}}">Tap me!</button>
</template>
<script type="application/dart">
import 'dart:html';
import 'package:polymer/polymer.dart';
import 'package:template_binding/template_binding.dart';
main() {
initPolymer().run(() {
Polymer.onReady.then((_) {
var template = document.querySelector('template');
templateBind(template).model = new MyModel();
});
});
}
class MyModel extends Observable {
//$['mybutton'] wont works there
#observable String value = 'something';
buttonTap() => print('tap!');
}
</script>
</body>
</html>
Unfortunately, the whole model now extends Observable, every binding seems to work, but the PolymerElement array selector $['foo'] cant be used anymore...
Is there any easy way to implement this $['id'] selector into an Observable model?
I would suggest to use a normal Polymer element instead of auto-binding-dart.
Then you don't have to care about differences and you need no 'main'.
I always start a Polymer project with an <app-element> Polymer element that acts as main() and container for the entire app.
I also would suggest to not use inline code.
As far as I know it has some limitations especially debugging is not supported (might be fixed already, I don't know because I never use it).
To make $ work you need a small and simple workaround;
import 'dart:html';
import 'package:polymer/polymer.dart';
import 'package:template_binding/template_binding.dart';
Map<String, dynamic> $; // we define our own '$'
main() {
initPolymer().run(() {
Polymer.onReady.then((_) {
var template = document.querySelector('template') as Polymer;
$ = template.$; // we assign template.$ to our own '$' so we can omit the 'template' part
templateBind(template).model = new MyModel();
});
});
}
class MyModel extends Observable {
//$['mybutton'] wont work there - it can't because this is outside of a method
#observable String value = 'something';
buttonTap() {
print($['mybutton'].id); // here it works
print('tap!');
}
}
I have created a sample app to test the Dart Route API. I have the following code:
urls.dart
library urls;
import 'package:route/url_pattern.dart';
final homeUrl = new UrlPattern(r'/');
final otherScreenUrl = new UrlPattern(r'/other_screen/');
main.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Test</title>
</head>
<body>
<div id="sample_container_id">
<p id="sample_text_id"></p>
</div>
<script type="application/dart" src="main.dart"></script>
<script src="packages/browser/dart.js"></script>
</body>
</html>
main.dart
import 'dart:html';
import 'package:route/client.dart';
import 'urls.dart';
void main() {
var router = new Router()
..addHandler(homeUrl, _showHome)
..addHandler(otherScreenUrl, _showOtherScreen)
..listen();
querySelector("#sample_text_id")
..text = "Click me!"
..onClick.listen(_gotoOtherScreen);
}
_gotoOtherScreen(MouseEvent event) {
// I am trying to navigate to the "other screen" by using history.pushState here
window.history.pushState({'url' : otherScreenUrl}, "other screen", otherScreenUrl);
}
_showHome(String path) {
querySelector("#other_element")
..remove();
}
_showOtherScreen(String path) {
querySelector("#sample_container_id")
..append(new SpanElement()
..innerHtml = "now in other screen"
..id = "other_element");
}
I am getting the following errors when running the app and then clicking on the <p> tag:
Breaking on exception: Illegal argument(s): No handler found for
/test/web/main.html
Exception: Illegal argument(s): No handler found for
/test/web/main.html Router._getUrl (package:route/client.dart:53:7)
Router.handle (package:route/client.dart:71:22)
Router.listen. (package:route/client.dart:102:15)
Breaking on exception: type 'UrlPattern' is not a subtype of type
'String' of 'url'.
Exception: type 'UrlPattern' is not a subtype of type 'String' of
'url'. _gotoOtherScreen
(http://127.0.0.1:3030/test/web/main.dart:18:27)
How is the Route API supposed to be used? What am I doing wrong?
The following is the updated code that solves the above issues:
urls.dart
library urls;
import 'package:route/url_pattern.dart';
final homeUrl = new UrlPattern(r'(.*)/');
final homeUrlWithFile = new UrlPattern(r'(.*)/main.html');
final otherScreenUrl = new UrlPattern(r'(.*)/other_screen');
main.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Test</title>
</head>
<body>
<div id="sample_container_id">
click me!!
</div>
<script type="application/dart" src="main.dart"></script>
<script src="packages/browser/dart.js"></script>
</body>
</html>
main.dart
import 'dart:html';
import 'package:route/client.dart';
import 'urls.dart';
void main() {
var router = new Router()
..addHandler(homeUrl, _showHome)
..addHandler(homeUrlWithFile, _showHome)
..addHandler(otherScreenUrl, _showOtherScreen)
..listen();
}
_showHome(String path) {
var e = querySelector("#other_element");
if (e != null) e.remove();
}
_showOtherScreen(String path) {
querySelector("#sample_container_id")
..append(new SpanElement()
..innerHtml = "now in other screen"
..id = "other_element");
}
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.
How do I dynamically load a snippet of HTML and insert it into my web page? I am using Dart.
Glad you asked! Using Dart for this task isn't much different than JavaScript, except you get typing, code completion, and a slick editing experience.
First, create the snippet.html:
<p>This is the snippet</p>
Next, create the application. Notice the use of XMLHttpRequest to request the snippet. Also, use new Element.html(string) to create a block of HTML from a string.
import 'dart:html';
void main() {
var div = querySelector('#insert-here');
HttpRequest.getString("snippet.html").then((resp) {
div.append(new Element.html(resp));
});
}
Finally, here's the host HTML page:
<!DOCTYPE html>
<html>
<head>
<title>dynamicdiv</title>
</head>
<body>
<h1>dynamicdiv</h1>
<div id="insert-here"></div>
<script type="application/dart" src="dynamicdiv.dart"></script>
<script src="packages/browser/dart.js"></script>
</body>
</html>
main.dart:
import 'dart:html';
DivElement div = querySelector('div');
main() async {
String template = await HttpRequest.getString("template.html");
div.setInnerHtml(template, treeSanitizer: NodeTreeSanitizer.trusted);
}
template.html:
<h1>Hello world.</h1>
Check my bird... <em>it flies</em> !
<img src="https://www.dartlang.org/logos/dart-bird.svg">
For the full example, that runs out of the box, see:
https://gist.github.com/kasperpeulen/536b021ac1cf397d4e6d
Note that you need 1.12 to get NodeTreeSanitizer.trusted working.
You can try this example.
https://jsfiddle.net/kofwe39d/ (JS compiled from Dart source code.)
web/main.dart
import 'dart:async';
import 'dart:html';
import 'package:virtual_dom/components/component.dart';
import 'package:virtual_dom/features/state.dart';
import 'package:virtual_dom/helpers/h.dart';
import 'package:virtual_dom/helpers/mount.dart';
import 'package:virtual_dom/helpers/styles.dart';
import 'package:virtual_dom/helpers/vhtml.dart';
void main() {
final app = document.getElementById('app')!;
mount(app, _App());
}
class _App extends Component {
#override
Object render() {
final timer = State.get('timer', () => 3);
final setTimer = State.set<int>('timer');
if (timer > 0) {
Timer(Duration(seconds: 1), () {
setTimer(timer - 1);
});
}
final html = timer > 0
? ''
: '''
Hello, <strong>World!</strong>
''';
final style = styles({'padding': '6px'});
return h('div', {
'style': style
}, [
if (timer > 0) '$timer sec',
h('p', 'Your html:'),
vHtml('div', html),
]);
}
}
web/index.html
<!DOCTYPE html>
<html style="height: 100%;">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Example application</title>
<link rel="stylesheet" href="normalize.css">
<link rel="stylesheet" href="styles.css">
<script defer src="main.dart.js"></script>
</head>
<body style="height: 100%; font-family: Verdana,sans-serif; font-size:15px; line-height:1.5">
<div id="app" style="height: 100%;"></div>
</body>
</html>