Specify Stubonly for Client-only Components"
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== Values of Stubonly: true, false and inherit == | == Values of Stubonly: true, false and inherit == | ||
− | The default value of the <tt>stubonly</tt> property is <tt>inherit</tt> | + | The default value of the <tt>stubonly</tt> property is <tt>inherit</tt>. It means the value is the same as its parent's, if any, or <tt>false</tt>, if no parent at all. Thus, if a component's <tt>stubonly</tt> is specified with <tt>true</tt>, all its descendants are stub-only too, unless <tt>false</tt> is specified explicitly. For example, in the following snippet, only <tt>textbox</tt> is <i>not</i> stub-only, while <tt>hbox</tt>, <tt>splitter</tt>, <tt>listbox</tt>, |
<tt>listitem</tt> and labels are all stub-only. | <tt>listitem</tt> and labels are all stub-only. | ||
Revision as of 10:53, 9 August 2010
This documentation is for an older version of ZK. For the latest one, please click here.
Overview
[since 5.0.4][ZK EE]
It is common that the states of some components are not required to maintain at the server. A typical example is that an application might use some components, such as hbox, for layout and won't access it again after rendered. To minimize the memory footprint, ZK supports a special property called stubonly (Component.setStubonly(String)). Once specified with true, its states won't be maintained at the server (and all states are maintained at the client). For example,
<hbox stubonly="true">
</hbox>
Values of Stubonly: true, false and inherit
The default value of the stubonly property is inherit. It means the value is the same as its parent's, if any, or false, if no parent at all. Thus, if a component's stubonly is specified with true, all its descendants are stub-only too, unless false is specified explicitly. For example, in the following snippet, only textbox is not stub-only, while hbox, splitter, listbox, listitem and labels are all stub-only.
<hbox stubonly="true">
a stub-only label
<textbox stubonly="false"/>
<splitter/>
<listbox>
<listitem label="also stubonly"/>
</listbox>
</hbox>
Limitation of Stub Components
When a component is stub only, it will be replaced with a special component called a stub component (StubComponent). Furthermore, stub components might be merged to minimize the memory further. The application shall not access the component again if it is specified as stub only.
Invalidation
While a stub component cannot be invalidated directly, it is safe to invalidate its parent. ZK will rerender all non-stub components and retain the states of stub components at the client. For example, in the following example it is safe to click the invalidate button. For end user's point of view, there is no difference if stubonly is specified or not.
<window>
<button label="self.parent.invalidate()"/>
<vbox stubonly="true">
stubonly <textbox/>
</vbox>
</window>