Package org.apache.wicket

Class AttributeModifier

java.lang.Object
org.apache.wicket.behavior.Behavior
org.apache.wicket.AttributeModifier
All Implemented Interfaces:
Serializable, IComponentAwareEventSink, IComponentAwareHeaderContributor, IClusterable
Direct Known Subclasses:
AttributeAppender
public class AttributeModifier extends Behavior implements IClusterable
This class allows a tag attribute of a component to be modified dynamically with a value obtained from a model object. This concept can be used to programmatically alter the attributes of components, overriding the values specified in the markup. The two primary uses of this class are to allow overriding of markup attributes based on business logic and to support dynamic localization. The replacement occurs as the component tag is rendered to the response.

The attribute whose value is to be modified must be given on construction of the instance of this class along with the model containing the value to replace with.

If an attribute is not in the markup, this modifier will add an attribute.

Instances of this class should be added to components via the Component.add(Behavior...) method after the component has been constructed.

It is possible to create new subclasses of AttributeModifier by overriding the newValue(String, String) method. For example, you could create an AttributeModifier subclass which appends the replacement value like this: 

 new AttributeModifier("myAttribute", model)
 {
        protected String newValue(final String currentValue, final String replacementValue)
        {
                return currentValue + replacementValue;
        }
 };
Author:
Chris Turner, Eelco Hillenius, Jonathan Locke, Martijn Dashorst, Ralf Ebert
See Also:

  • Field Details

  • Constructor Details

    • AttributeModifier

      public AttributeModifier(String attribute, IModel<?> replaceModel)
      Create a new attribute modifier with the given attribute name and model to replace with. The attribute will be added with the model value or the value will be replaced with the model value if the attribute is already present.
      Parameters:
      attribute - The attribute name to replace the value for
      replaceModel - The model to replace the value with

    • AttributeModifier

      public AttributeModifier(String attribute, Serializable value)
      Create a new attribute modifier with the given attribute name and model to replace with. The attribute will be added with the model value or the value will be replaced with the value if the attribute is already present.
      Parameters:
      attribute - The attribute name to replace the value for
      value - The value for the attribute

  • Method Details

    • detach

      public final void detach(Component component)
      Detach the value if it was a IDetachable. Internal method, shouldn't be called from the outside. If the attribute modifier is shared, the detach method will be called multiple times.
      Overrides:
      detach in class Behavior
      Parameters:
      component - the model that initiates the detachment

    • getAttribute

      public final String getAttribute()
      Returns:
      the attribute name to replace the value for

    • onComponentTag

      public final void onComponentTag(Component component, ComponentTag tag)
      Description copied from class: Behavior
      Called any time a component that has this behavior registered is rendering the component tag.
      Overrides:
      onComponentTag in class Behavior
      Parameters:
      component - the component that renders this tag currently
      tag - the tag that is rendered

    • replaceAttributeValue

      public final void replaceAttributeValue(Component component, ComponentTag tag)
      Checks the given component tag for an instance of the attribute to modify and if all criteria are met then replace the value of this attribute with the value of the contained model object.
      Parameters:
      component - The component
      tag - The tag to replace the attribute value for

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • getReplaceModel

      protected final IModel<?> getReplaceModel()
      Gets the replacement model. Allows subclasses access to replace model.
      Returns:
      the replace model of this attribute modifier

    • newValue

      protected Serializable newValue(String currentValue, String replacementValue)
      Gets the value that should replace the current attribute value. This gives users the ultimate means to customize what will be used as the attribute value. For instance, you might decide to append the replacement value to the current instead of just replacing it as is Wicket's default.
      Parameters:
      currentValue - The current attribute value. This value might be null!
      replacementValue - The replacement value. This value might be null!
      Returns:
      The value that should replace the current attribute value

    • replace

      public static AttributeModifier replace(String attributeName, IModel<?> value)
      Creates a attribute modifier that replaces the current value with the given value.
      Parameters:
      attributeName -
      value -
      Returns:
      the attribute modifier
      Since:
      1.5

    • replace

      public static AttributeModifier replace(String attributeName, Serializable value)
      Creates a attribute modifier that replaces the current value with the given value.
      Parameters:
      attributeName -
      value -
      Returns:
      the attribute modifier
      Since:
      1.5

    • append

      public static AttributeAppender append(String attributeName, IModel<?> value)
      Creates a attribute modifier that appends the current value with the given value using a default space character (' ') separator.
      Parameters:
      attributeName -
      value -
      Returns:
      the attribute modifier
      Since:
      1.5
      See Also:

    • append

      public static AttributeAppender append(String attributeName, Serializable value)
      Creates a attribute modifier that appends the current value with the given value using a default space character (' ') separator.
      Parameters:
      attributeName -
      value -
      Returns:
      the attribute modifier
      Since:
      1.5
      See Also:

    • prepend

      public static AttributeAppender prepend(String attributeName, IModel<?> value)
      Creates a attribute modifier that prepends the current value with the given value using a default space character (' ') separator.
      Parameters:
      attributeName -
      value -
      Returns:
      the attribute modifier
      Since:
      1.5
      See Also:

    • prepend

      public static AttributeAppender prepend(String attributeName, Serializable value)
      Creates a attribute modifier that prepends the current value with the given value using a default space character (' ') separator.
      Parameters:
      attributeName -
      value -
      Returns:
      the attribute modifier
      Since:
      1.5
      See Also:

    • remove

      public static AttributeModifier remove(String attributeName)
      Creates a attribute modifier that removes an attribute with the specified name
      Parameters:
      attributeName - the name of the attribute to be removed
      Returns:
      the attribute modifier
      Since:
      1.5