ZK Component Reference/Base Components/InputElement

Input Element

• Demonstration: N/A
• Java API: InputElement
• JavaScript API: InputWidget

Employment/Purpose

InputElement is a super class for components which provie user key input, such as textbox, intbox, decimalbox, doublebox, datebox, timebox, spinner, combobox, and bandbox.

Some features are implemented in this class, such as constraint, disabled, maxlength, name, readonly, and so on.

You should not use this class directly, please use the inherited class.

Example

<grid>
	<rows>
		<row>
			UserName <textbox value="Jerry" width="150px" />
		</row>
		<row>
			Password <textbox type="password" value="foo" width="150px" />
		</row>
		<row>
			Phone: <intbox constraint="no negative,no zero" width="150px" value="12345678" />
		</row>
		<row>
			Weight: <decimalbox format="###.##" value="154.32" width="150px" />
		</row>
		<row>
			Birthday: <datebox id="db" width="150px" />			
		</row>
		<row>
			E-mail:
			<textbox width="150px" value="zk@zkoss.org"
				constraint="/.+@.+\.[a-z]+/: Please enter an e-mail address" />
		</row>
	</rows>
</grid>

Validation

There are two ways to validate the value entered by an user: implementing Constraint or throwing WrongValueException.

Constraint

An input element can be associated with a constraint (Constraint) to validate the value entered by an user. There is a default implementation called SimpleConstraint that can handle many conditions. If it is not enough, you can implement your own constraint, or throwing WrongValueException as described in the next sections.

To use the default constraint, you could specify a list of conditions in InputElement.setConstraint(String), such as no positive and no empty. For example,

<textbox constraint="no empty"/>
<intbox constraint="no negative,no zero"/>

To specify a regular expression, you could have to use / to enclose the regular expression as follows.

<textbox constraint="/.+@.+\.[a-z]+/"/>

Notice that the above statement is XML, so do not use \\ to specify a backslash. On the other hand, it is required, if writing in Java:

new Textbox().setContraint("/.+@.+\\.[a-z]+/");

Notice that it is allowed to mix regular expression with other constraints by separating them with comma.

If you prefer to display an application dependent message instead of default one, you could append the constraint with colon and the message you want to display when failed.

<textbox constraint="/.+@.+\.[a-z]+/: e-mail address only"/>
<datebox constraint="no empty, no future: now or never"/>

Notice that the error message, if specified, must be the last element and start with colon. To support multilingual, you could use the l function as depicted in ZK Developer's Reference.

<?taglib uri="http://www.zkoss.org/dsp/web/core" prefix="c"?>
<textbox constraint="/.+@.+\.[a-z]+/: ${c:l('err.email.required')}"/>

The default constraints

Condition	Description
no empty	Empty is not allowed.
no future	Date in the future is not allowed.
no negative	Negative numbers are not allowed.
no past	Date in the past is not allowed.
no positive	Postive numbers are not allowed.
no today	Today is not allowed.
no zero	Zero numbers are not allowed.
between yyyyMMdd and yyyyMMdd	Date only allowed between the specified range. The format must be yyyyMMdd, such as <datebox constraint="between 20071225 and 20071203"/>
after yyyyMMdd	Date only allowed after (and including) the specified date. The format must be yyyyMMdd, such as <datebox constraint="after 20071225"/>
before yyyyMMdd	Date only allowed before (and including) the specified date. The format must be yyyyMMdd, such as <datebox constraint="before 20071225"/>

Custom Constraint

If you want a custom constraint, you could implement Constraint and specify it in the constraint property (InputElement.setConstraint(Constraint)).

public class EventNumberConstraint implements Constraint {
	public void validate(Component comp, Object value)
	throws WrongValueException {
		if (value != null && (value.intValue() & 1) != 0) //assume used with intbox
			throw new WrongValueException(comp, "Only even numbers are allowed, not "+value);
	}
}

If the validation fails, just throw WrongValue to indicate it. Notice that you have to specify which component causes the exception as shown in line 5.

To specify it to the constraint property, you have to instantiate it first by use of the new function as shown below

<?taglib uri="http://www.zkoss.org/dsp/web/core" prefix="c"?>
<textbox constraint="${c:new('foo.EventNumberConstraint')}"/>

Display Error Message in Custom Way

Instead of the default error box, you could provide a custom approach by implementing CustomConstraint (with Constraint). Then, CustomConstraint.showCustomError(Component, WrongValueException) will be invoked when an exception is caught. For example,

<window title="Custom Constraint" border="normal">
	<zscript><![CDATA[
		class MyConst implements Constraint, CustomConstraint {
			//Constraint//
			public void validate(Component comp, Object value) {
	        	if (value == null || ((Integer)value).intValue() < 100)
					throw new WrongValueException(comp, "At least 100 must be specified");
			}
	     	//CustomConstraint//
			public void showCustomError(Component comp, WrongValueException ex) {
				errmsg.setValue(ex != null ? ex.getMessage(): "");
			}
 		}
		Constraint ctt = new MyConst();
    ]]>
    </zscript>
	<hlayout>
		Enter a number at least 100:
		<intbox constraint="${ctt}" />
		<label id="errmsg" />
	</hlayout>
</window>

And, here is the result

WrongValueException

In additions to throwing WrongValueException in Constraint.validate(Component, Object), you can throw WrongValueException in other situation. For example, you can validate the user name and password when the user presses the login button. For example,

public class FooComposer extends GenericForwardComposer {
  private Textbox username;
  private Textbox password;

  public void onClick$login() {
    username.clearErrorMessage(); //important to clear the previous error, if any
    if (examine(username, password)) {
      //success
    } else {
      throw new WrongValueException(username, "Not a valid username or password. Please retry.");
    }
  }
}

However, notice that you have to clear the error message manually by invoking InputElement.clearErrorMessage(). Otherwise, the error message will remain there unless Textbox.setValue(String) is called.

Properties

Inplace

All input elements can have the in-place-editing functionality, like the combobox, textbox, datebox, and so on.

<grid>
  <rows>
    <row>
      <textbox inplace="true"/>
      <combobox inplace="true"/>
      <datebox inplace="true"/>
    </row>
  </rows>
</grid>

Supported Events

Name	Event Type
onChange	Event: InputEvent Denotes the content of an input component has been modified by the user.
onChanging	Event: InputEvent Denotes that user is changing the content of an input component. Notice that the component's content (at the server) won't be changed until onChange is received. Thus, you have to invoke the getValue method in the InputEvent class to retrieve the temporary value.
onSelection	Event: SelectionEvent Denotes that user is selecting a portion of the text of an input component. You can retrieve the start and end position of the selected text by use of the getStart and getEnd methods.
onFocus	Event: Event Denotes when a component gets the focus. Remember event listeners execute at the server, so the focus at the client might be changed when the event listener for onFocus got executed.
onBlur	Event: Event Denotes when a component loses the focus. Remember event listeners execute at the server, so the focus at the client might be changed when the event listener for onBlur got executed.
onError	Event: ErrorEvent Denotes when a component caused a validation error.

Supported Children

*None

Use cases

Version	Description	Example Location

Version History

Version	Date	Content