| To modify tag attributes we can use class @org.apache.wicket.AttributeModifier@. This class extends @org.apache.wicket.behavior.Behavior@ and can be added to any component via the @Component@'s @add@ method. Class @Behavior@ is used to expand component functionalities and it can also modify component markup. We will see this class in detail later in [chapter 19.1|guide:advanced_1]. |
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| As first example of attribute manipulation let's consider a @Label@ component bound to the following markup: |
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| {code:html} |
| <span wicket:id="simpleLabel"></span> |
| {code} |
| |
| Suppose we want to add some style to label content making it red and bolded. We can add to the label an @AttributeModifier@ which creates the tag attribute @style@ with value @"color:red;font-weight:bold"@: |
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| {code} |
| label.add(new AttributeModifier("style", "color:red;font-weight:bold")); |
| {code} |
| |
| If attribute @style@ already exists in the original markup, it will be replaced with the value specified by @AttributeModifier@. If we don't want to overwrite the existing value of an attribute we can use subclass @AttributeAppender@ which will append its value to the existing one: |
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| {code} |
| label.add(new AttributeAppender("style", "color:red;font-weight:bold")); |
| {code} |
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| We can also create attribute modifiers using factory methods provided by class @AttributeModifier@ and it's also possible to prepend a given value to an existing attribute: |
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| {code} |
| //replaces existing value with the given one |
| label.add(AttributeModifier.replace("style", "color:red;font-weight:bold")); |
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| //appends the given value to the existing one |
| label.add(AttributeModifier.append("style", "color:red;font-weight:bold")); |
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| //prepends the given value to the existing one |
| label.add(AttributeModifier.prepend("style", "color:red;font-weight:bold")); |
| {code} |
