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= EL Expression = | = EL Expression = | ||
− | The EL expression supported by iZUML is actually a JavaScript snippet. It could be any valid JavaScript expression. Unlike ZUML, iZUML's EL expressions start with < | + | The EL expression supported by iZUML is actually a JavaScript snippet. It could be any valid JavaScript expression. Unlike ZUML, iZUML's EL expressions start with <code>#{</code> and end with <code>}</code><ref>For 5.0.7 and older version, iZUML's expressions start with <code>${</code>. Since 5.0.8, <code>#{</code> is recommended, thought <code>${</code> is still valid (for backward compatibility) but deprecated.</ref>. Because the starting character of EL expressions is different, it is easier to embed iZUML's EL expression in a ZUML page. |
Here is a list of built-in variables (aka., implicit objects) that you can access in the EL expressions. | Here is a list of built-in variables (aka., implicit objects) that you can access in the EL expressions. | ||
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| 5.0.8 | | 5.0.8 | ||
| August 2011 | | August 2011 | ||
− | | The starting character of iZUML's EL expressions is changed to < | + | | The starting character of iZUML's EL expressions is changed to <code>#{</code>, so it is easier to embed iZUML in a ZUML page. For backward compatibility, <code>${</code> is still valid but deprecated. |
|- | |- | ||
| 6.0.0 | | 6.0.0 |
Latest revision as of 03:22, 18 January 2022
Overview
ZK 7+: support discontinued since ZK7 and above ZK 6: Available in all editions ZK 5: Available in ZK PE and EE only
iZUML is a client-side version of ZUML. iZUML is interpreted at the client. You could embed and use iZUML in any Web page, including a ZUML document and pure HTML pages. But, for the sake of description, here we only illustrate the use in pure HTML pages. With some modification, readers could apply it to ZUML document, JSP and other technologies too.
For composing UI in JavaScript at the client, please refer to the Client-side UI Composing section.
How to Embed iZUML into HTML
It is typically placed inside an HTML DIV tag, though you can choose other kind of tags. Furthermore, it is suggested to enclose the iZUML document with an HTML comment (<!-- and -->) such that the page can be interpreted correctly by the browser. For example,
<div id="main" display="none">
<!--
<window>
What's your name? <textbox onOK="sayHello(this)"/>
</window>
<separator bar="true"/>
-->
</div>
Of course, you construct an iZUML document dynamically such as the follows.
var zuml = '<window title="' + title +'">What\'s your name? <textbox/></window>';
Specify ZK JavaScript Files
Before using iZUML or other client-side feature, ZK's JavaScript files must be specified (and loaded). If you are using with ZUML, they are loaded automatically. However, if you are using so-called pure-client approach (such as a static HTML file), you have to specify them explicitly as follows.
<script type="text/javascript" src="/zkdemo/zkau/web/js/zk.wpd" charset="UTF-8">
</script>
<script type="text/javascript" src="/zkdemo/zkau/web/js/zk.zuml.wpd" charset="UTF-8">
</script>
Notice that it is not required if you are using with a ZUML document.
How to Create Widgets from iZUML
If the iZUML document is embedded in a HTML tag, you can use Parser.createAt(String, Map, Map, Function) to create widgets. If you construct the iZUML document as a string, you could use Parser.create(Widget, String, Map, Function).
EL Expression
The EL expression supported by iZUML is actually a JavaScript snippet. It could be any valid JavaScript expression. Unlike ZUML, iZUML's EL expressions start with #{
and end with }
[1]. Because the starting character of EL expressions is different, it is easier to embed iZUML's EL expression in a ZUML page.
Here is a list of built-in variables (aka., implicit objects) that you can access in the EL expressions.
Name | Description |
---|---|
this
|
It references that a widget has been created.
If the EL expression is part of the <window title="some">
#{this.getTitle()}...
<texbox if="#{this.border}"/>
</window>
where <window title="some">
<textbox value="#{this.parent.getTitle()}">
</window>
where |
_
|
The context passed to the argument named var of Parser.createAt(String, Map, Map, Function) and Parser.create(Widget, String, Map, Function).
#{_.info.name}
|
- ↑ For 5.0.7 and older version, iZUML's expressions start with
${
. Since 5.0.8,#{
is recommended, thought${
is still valid (for backward compatibility) but deprecated.
Built-in Attributes
forEach
<window title="Test" border="normal">
<label forEach="#{[this.getTitle(), this.getBorder()}"/>
</window>
- Notice
- Unlike widget attributes,
this
references to the parent widget, which iswindow
in the above case.
- Unlike widget attributes,
if
<button label="Edit" if="#{_.login}/>
unless
<button label="View" unless="#{_.inEditMode}"/>
Built-in Element
attribute
<button label="Click">
<attribute name="onClick">
this.parent.setTitle("Click");
</attribute>
</button>
is equivalent to
<button label="Click onClick="this.parent.setTitle('click')"/>
zk
The zk element doesn't represent a widget.
<zk forEach="#{[1, 2, 3]}">
#{each} <textbox value="#{each}"/>
</zk>
Notes
script
When <script>
is specified in iZUML, it actually refers to the script widget (Script) (rather than HTML SCRIPT tag).
style
When <style>
is specified in iZUML, it actually refers to the style widget (Style) (rather than HTML STYLE tag).
Example
For a more complete example, please refer to Small Talk: ZK 5.0 and Client-centric Approach.
Version History
Version | Date | Content |
---|---|---|
5.0.8 | August 2011 | The starting character of iZUML's EL expressions is changed to #{ , so it is easier to embed iZUML in a ZUML page. For backward compatibility, ${ is still valid but deprecated.
|
6.0.0 | October 2011 | iZUML is available to all editions, including CE, PE and EE. |