聚合物Dom重复绑定到内容 [英] Polymer Dom-Repeat Binding to Content
问题描述
在聚合物1.2.3中，dom-repeat是否可以使用内容作为模板并将值绑定到所提供的元素上?
In polymer 1.2.3, Is it possible for a dom-repeat to use content as a template and bind values to the elements provided?
自定义元素:
<dom-module id="modify-collection">
<template>
<div>
<template is="dom-repeat" items="[[collection]]">
<content></content>
</template>
</div>
</template>
</dom-module>
用法:
<modify-collection collection="{{things}}">
<list-item resource="[[item]]"></list-item>
</modify-collection>
我在没有帮助的情况下查看了以下资源:
I've looked at the following resources without help:
https://github.com/grappendorf/grapp-template-ref
https://github.com/Trakkasure/dom-bindref
https://github.com/Polymer/polymer/issues/1852
https://github.com/Polymer/polymer/pull/2196
更新2016-02-03 :来自Polymer团队(PR#2196)，计划在将来为此提供更好的支持，以帮助解决某些缺点.
https://github.com/Polymer/polymer/pull/2196
Update 2016-02-03: From the Polymer Team(PR #2196), better support for this is planned in the future, to help address some of the shortcomings.
推荐答案
TLDR
解决方案2稍显冗长，但效果最好.它还允许您动态地选择模板，也许基于模型的属性. (请参阅解决方案2:高级示例)
TLDR
Solution 2 while a little more verbose, seems to work best. It also allows you to dynamically choose your template, perhaps based on a model's attributes. (See Solution 2: Advanced Example)
在这个简单的示例中，发生了很多事情，包括模板化，在阴影，阴影和浅色阴影之间获取"内容，当然还有数据绑定.
A Lot of stuff is happening in this simple example including templatizing, "getting" content between shadow?, shady, and light doms, and of course data-binding.
这个问题提供了一些见识，但是没有Polymer 0.5's injectBoundHtml，它实际上是行不通的(
This question provided some insight, but without Polymer 0.5's injectBoundHtml it wasn't really workable (Using template defined in light dom inside a Polymer element). The problem being that our data-bindings seem to get lost (AFAIK) when we try to copy an element using innerHTML to our template.
因此，否则，我们将无法使用数据绑定即时创建模板.因此，这两种解决方案都会提前将内容包装在模板中.这会导致html处于惰性状态，并允许Polymer在适当的时间进行数据绑定( http://www. html5rocks.com/en/tutorials/webcomponents/template/).
So without that we can't create our template on the fly with data-bindings. Thus both solutions wrap the content in a template ahead of time; this caused the html to be inert and allows Polymer to data-bind at the appropriate time (http://www.html5rocks.com/en/tutorials/webcomponents/template/).
如果您真的想了解所有内容，建议您阅读lib/template/dom-repeat.html，lib/template/templatizer.html，lib/annotations/annotations.html的聚合物src(约1500行).
If you really want to understand everything, I'd recommended reading the Polymer src for lib/template/dom-repeat.html, lib/template/templatizer.html, lib/annotations/annotations.html (~1500 lines).
请参见下面的债务人答案以获取改进解决方案1.
See btelle's answer below for an improved solution 1.
请注意，这种方法会导致dom-repeat不会自动呈现内容，因此我们将其手动称为呈现.
Note, this approach causes dom-repeat to not render content automatically, so we call render manually.
<dom-module id="modify-collection">
<template>
<div>
<content></content>
<template id="repeater" is="dom-repeat" items="[[collection]]"></template>
</div>
</template>
<script>
...
ready: function() {
this.$.repeater.templatize(this.querySelector('#templ'));
}
_changeCollection: function(item) {
this.push('collection', item);
this.$.repeater.render();
}
</script>
</dom-module>
用法
<modify-collection collection="{{things}}">
<template id="templ"><list-item resource="[[item]]"></list-item></template>
</modify-collection>
请注意，此用法与元素1不同，因为<template>必须具有is="dom-template"属性.
Note, that the usage of this varies from element 1, in that the <template> must have an is="dom-template" attribute.
(从此PR稍作修改: https://github.com/Polymer/polymer/pull/2196，最初基于 https://github.com/grappendorf/grapp-template-ref )
(Slightly modified from this PR: https://github.com/Polymer/polymer/pull/2196, originally based on https://github.com/grappendorf/grapp-template-ref)
!--
@license
Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
Code distributed by Google as part of the polymer project is also
subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-->
<!--
Portions of this code have been adapted from the `grapp-template-ref` element.
The original copyright notices are below.
-->
<!--
MIT License
Copyright (c) 2014-2015 Dirk Grappendorf, www.grappendorf.net
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-->
<!--
The `dom-ref` element is a custom `HTMLTemplateElement` type extension that
can be used to reference another template by id using the `ref` property.
`dom-bindref` accepts a `bind` property to bind an object to the referenced
template. By default the bound object can be accessed as `item`, this can be
changed using the `as` property.
Example:
```html
<template is="dom-template" id="template-bind"><span>[[item.key]]</span></template>
<template is="dom-ref" ref="template-bind" bind='{"key":"value"}'></dom-ref>
```
-->
<!-- <link rel="import" href="templatizer.html"> -->
<script>
Polymer({
is: 'dom-ref',
extends: 'template',
/**
* Fired whenever DOM is added or removed by this template (by
* default, rendering occurs lazily). To force immediate rendering, call
* `render`.
*
* @event dom-change
*/
properties: {
/**
* Reference to another template's id.
*/
ref: {
type: String,
observer: '_refChanged'
},
/**
* Object to be bound to referenced template.
*/
bind: {
type: Object,
observer: '_bindChanged'
},
/**
* The name of the variable to add to the binding scope for the
* element associated with a given template instance.
*/
as: {
type: String,
value: 'item'
}
},
behaviors: [
Polymer.Templatizer
],
ready: function() {
this.templatize(this);
},
attached: function() {
return this._stamp();
},
detached: function() {
return this._removeChildren();
},
_refChanged: function(newRef, oldRef) {
if (oldRef) {
this._removeChildren();
return this._stamp();
}
},
_bindChanged: function(newBind, oldBind) {
if (oldBind) {
this._removeChildren();
return this._stamp();
}
},
_stamp: function() {
var root, template, templateRoot, bind = {};
this._parent = Polymer.dom(this).parentNode;
root = this._parent;
while (Polymer.dom(root).parentNode) {
root = Polymer.dom(root).parentNode;
}
template = Polymer.dom(root).querySelector("template#" + this.ref);
// Check For Light Dom Elements that may be passed to this shadow root (Useful for: `<content></content>`)
if (!template) {
template = root.host.querySelector("template#" + this.ref);
}
// Check the whole document
if (!template) {
template = document.querySelector("template#" + this.ref);
}
bind[this.as] = this.bind;
// templateRoot = template.stamp(bind).root;
// Use this method until this lands: https://github.com/Polymer/polymer/pull/1889
templateRoot = (new template.ctor(bind, template)).root;
this._children = Array.prototype.slice.call(templateRoot.childNodes);
return Polymer.dom(this._parent).insertBefore(templateRoot, this);
},
_removeChildren: function() {
var child, i, len, ref, results;
if (this._children) {
ref = this._children;
results = [];
for (i = 0, len = ref.length; i < len; i++) {
child = ref[i];
results.push(Polymer.dom(this._parent).removeChild(child));
}
return results;
}
}
});
</script>
元素
<dom-module id="modify-collection">
<template>
<div>
<content></content>
<template is="dom-repeat" items="[[collection]]">
<template is="dom-ref" bind="[[item]]" ref="templ"></template>
</template>
</div>
</template>
</dom-module>
用法
<modify-collection collection="{{things}}">
<template id="templ" is="dom-template"><list-item resource="[[item]]"></list-item></template>
</modify-collection>
高级元素
用法不变.
Advanced Element
Usage does not change from above.
我们在这里做的是引入一个间接级别，允许我们包装传递给元素的模板(在我们的示例中，带有一个覆盖层).
What we do here is introduce a level of indirection, allowing us to wrap a template passed to our element (in our example, with an overlay).
<dom-module id="modify-collection">
<template>
<div>
<content></content>
<template id="wrapper" is="dom-template">
<div class="overlay">
<template is="dom-ref" bind="[[item]]" ref="templ"></template>
</div>
</template>
<template is="dom-repeat" items="[[collection]]">
<template is="dom-ref" bind="[[item]]" ref="[[_templateRef(_overlayMode)]]"></template>
</template>
</div>
</template>
<script>
...
properties: {
_overlayMode: {
type: Boolean,
value: false
}
},
_templateRef: function(overlayMode) {
return overlayMode ? 'wrapper' : 'templ';
}
</script>
</dom-module>
这篇关于聚合物Dom重复绑定到内容的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
