6.41.  < rich:dragSupport >

6.41.1. Description

This component defines a subtree of the component tree as draggable for drag-and-drop operations. Within such a "drag zone," you can click the mouse button on an item and drag it to any component that supports drop operations (a "drop zone"). It encodes all the necessary JavaScript for supporting drag-and-drop operations.

<rich:dragSupport> component

Figure 6.72.  <rich:dragSupport> component


6.41.2. Key Features

  • Encodes all necessary JavaScript to perform drag actions

  • Can be used within any component type that provides the required properties for drag operations

  • Supports drag-and-drop between different forms

Table 6.154. rich : dragSupport attributes

Attribute NameDescription
actionMethodBinding pointing at the application action to be invoked, if this UIComponent is activated by you, during the Apply Request Values or Invoke Application phase of the request processing lifecycle, depending on the value of the immediate property
actionListenerMethodBinding pointing at method accepting an ActionEvent with return type void
ajaxSingleif "true", submits ONLY one field/link, instead of all form controls
bindingThe attribute takes a value-binding expression for a component property of a backing bean
bypassUpdatesIf "true", after process validations phase it skips updates of model beans on a force render response. It can be used for validating components input
dataSerialized (on default with JSON) data passed on the client by a developer on AJAX request. It's accessible via "data.foo" syntax
disableDefaultDisable default action for target event (append "return false;" to JavaScript)
dragIndicatorId of a component that is used as drag pointer during the drag operation
dragListenerMethodBinding representing an action listener method that will be notified after drag operation
dragTypeA drag zone type that is used for zone definition, which elements can be accepted by a drop zone
dragValueData to be sent to a drop zone after a drop event
eventsQueueName of requests queue to avoid send next request before complete other from same event. Can be used to reduce number of requests of frequently events (key press, mouse move etc.)
focusid of element to set focus after request completed on client side
grabbingCursorslist of comma separated cursors that indicates then the you has grabbed something
grabCursorslist of comma separated cursors that indicates then you can grab and drag an object
idEvery component may have a unique id that is automatically created if omitted
ignoreDupResponsesAttribute allows to ignore an Ajax Response produced by a request if the newest 'similar' request is in a queue already. ignoreDupResponses="true" does not cancel the request while it is processed on the server, but just allows to avoid unnecessary updates on the client side if the response isn't actual now
immediateTrue means, that the default ActionListener should be executed immediately (i.e. during Apply Request Values phase of the request processing lifecycle), rather than waiting until the Invoke Application phase
limitToListIf "true", updates on client side ONLY elements from this 'reRender' property. If "false" (default) updates all rendered by ajax region components
onbeforedomupdateJavaScript code for call before DOM has been updated on client side
oncompleteJavaScript code for call after request completed on client side
ondragendA JavaScript event handler called after a drag operation
ondragstartA JavaScript event handler called before drag operation
ondropoutA JavaScript event handler called after a out operation
ondropoverA JavaScript event handler called after a drop operation
onsubmitJavaScript code for call before submission of ajax event
processId['s] (in format of call UIComponent.findComponent()) of components, processed at the phases 2-5 in case of AjaxRequest caused by this component. Can be single id, comma-separated list of Id's, or EL Expression with array or Collection
renderedIf "false", this component is not rendered
requestDelayAttribute defines the time (in ms.) that the request will be wait in the queue before it is ready to send. When the delay time is over, the request will be sent to the server or removed if the newest 'similar' request is in a queue already
reRenderId['s] (in format of call UIComponent.findComponent()) of components, rendered in case of AjaxRequest caused by this component. Can be single id, comma-separated list of Id's, or EL Expression with array or Collection
statusID (in format of call UIComponent.findComponent()) of Request status component
timeoutResponse waiting time on a particular request. If a response is not received during this time, the request is aborted
valueThe current value for this component

Table 6.155. Component identification parameters

NameValue
component-typeorg.richfaces.DragSupport
component-classorg.richfaces.component.html.HtmlDragSupport
component-familyorg.richfaces.DragSupport
renderer-typeorg.richfaces.DragSupportRenderer
tag-classorg.richfaces.taglib.DragSupportTag

6.41.3. Creating the Component with a Page Tag

Here is a simple example as it could be used on a page:

Example:


...
    <h:panelGrid id="drag1">
        <rich:dragSupport dragType="item"/>
            <!--Some content to be dragged-->
    </h:panelGrid>
...

6.41.4. Creating the Component Dynamically Using Java

Example:


import org.richfaces.component.html.HtmlDragSupport;
...
HtmlDragSupport myDragZone = new HtmlDragSupport();
...

6.41.5. Details of Usage

The dragSupport tag inside a component completely specifies the events and JavaScript required to use the component and it's children for dragging as part of a drag-and-drop operation. In order to work, though, dragSupport must be placed inside a wrapper component that outputs child components and that has the right events defined on it. Thus, this example won't work, because the h:column tag doesn't provide the necessary properties for redefining events on the client:

Example:


...
    <h:column>
        <rich:dragSupport dragIndicator=":form:iii" dragType="text">
            <a4j:actionParam value="#{caps.name}" name="name"/>
        </rich:dragSupport>
        <h:outputText value="#{caps.name}"/> 
    </h:column>
...

However, using a4j:outputPanel as a wrapper inside h:column, the following code could be used successfully:

Example:


...
    <h:column>
        <a4j:outputPanel>
            <rich:dragSupport dragIndicator=":form:iii" dragType="text">
                <a4j:actionParam value="#{caps.name}" name="name"/>
            </rich:dragSupport>
            <h:outputText value="#{caps.name}"/> 
        </a4j:outputPanel>
    </h:column>
...

This code makes all rows of this column draggable.

One of the main attributes for dragSupport is "dragType", which associates a name with the drag zone. Only drop zones with this name as an acceptable type can be used in drag-and-drop operations. Here is an example:

Example:


...
    <h:panelGrid id="drag1">
        <rich:dragSupport dragType="singleItems" .../>
        <!--Some content to be dragged-->
    </h:panelGrid>      
...
    <h:panelGrid id="drag2">
        <rich:dragSupport dragType="groups" .../>
        <!--Some content to be dragged-->
    </h:panelGrid>      
...
    <h:panelGrid id="drop1">
        <rich:dropSupport acceptedTypes="singleItems" .../>
        <!--Drop zone content-->
    </h:panelGrid>
...

In this example, the drop1 panel grid is a drop zone that invokes drag-and-drop for drops of items from the first drag1 panel grid, but not the second drag2 panel grid. In the section about dropSupport, you will find an example that shows more detailed information about moving data between tables with drag and drop.

The dragSupport component also has a "value" attribute for passing data into the processing after a drop event.

One more important attribute for <rich:dragSupport> is the "dragIndicator" attribute that point to the component id of the <rich:dragIndicator> component to be used for dragged items from this drag zone. If it isn't defined, a default indicator for drag operations is used.

Finally, the component has the following extra attributes for event processing on the client:

  • ondragenter

  • ondragexit

You can use your own custom JavaScript functions to handle these events.

Note:

If you define width for a outputPanel, in Internet Explorer 6 you can perform a drag and drop operation, placing the mouse cursor on the text in the outputPanel only.

Information about the "process" attribute usage you can find here.

6.41.6. Look-and-Feel Customization

<rich:dragSupport> has no skin parameters and custom style classes, as the component isn't visual.

6.41.7. Relevant Resources Links

Here you can see the example of <rich:dragSupport> usage and sources for the given example.