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## 6.32. < rich:datascroller >

### 6.32.1. Description

The component designed for providing the functionality of tables scrolling using Ajax requests.

Figure 6.32. <rich:datascroller> component

### 6.32.2. Key Features

- Provides table scrolling functionality

- Built-in Ajax processing

- Provides fast controls

- Skin support

Table 6.115. rich : datascroller attributes

Attribute Name | Description
--- | ---
action | MethodBinding 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
actionListener | MethodBinding pointing at method accepting an ActionEvent with return type void
ajaxSingle | Boolean attribute which provides possibility to limit JSF tree processing(decoding, conversion/validation, value applying) to the component which send the request only.
align | This attribute specifies the position of the table with relatively to the document. Possible values are "left","center","right ". Default value is "center".
binding | The attribute takes a value-binding expression for a component property of a backing bean
boundaryControls | The attribute specifies the visibility of boundaryControls. Possible values are: "show" (controls are always visible ). "hide" (controls are hidden. "auto" (unnecessary controls are hidden). Default value is "show".
bypassUpdates | If "true", after process validations phase it skips updates of model beans on a force render response. It can be used for validating components input
data | Serialized (on default with JSON) data passed on the client by a developer on AJAX request. It's accessible via "data.foo" syntax
eventsQueue | Name 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.)
fastControls | The attribute specifies the visibility of fastControls. Possible values are: "show" (controls are always visible ). "hide" (controls are hidden. "auto" (unnecessary controls are hidden). Default value is "show".
fastStep | The attribute indicates pages quantity to switch onto when fast scrolling is used. Default value is "0".
focus | id of element to set focus after request completed on client side
for | ID of the table component whose data is scrollled
handleValue | Current handle value
id | Every component may have a unique id that is automatically created if omitted
ignoreDupResponses | Attribute 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. Default value is "true".
immediate | A flag indicating that this component value must be converted and validated immediately (that is, during Apply Request Values phase), rather than waiting until a Process Validations phase
inactiveStyle | Corresponds to the HTML style attribute for the inactive cell on scroller
inactiveStyleClass | Corresponds to the HTML class attribute for the inactive cell on scroller
limitToList | If "true", updates on client side ONLY elements from this 'reRender' property. If "false" (default) updates all rendered by ajax region components
maxPages | Maximum quantity of pages. Default value is "10".
onbeforedomupdate | JavaScript code for call before DOM has been updated on client side
onclick | HTML: a script expression; a pointer button is clicked
oncomplete | JavaScript code for call after request completed on client side
ondblclick | HTML: a script expression; a pointer button is double-clicked
onkeydown | HTML: a script expression; a key is pressed down
onkeypress | HTML: a script expression; a key is pressed and released
onkeyup | HTML: a script expression; a key is released
onmousedown | HTML: script expression; a pointer button is pressed down
onmousemove | HTML: a script expression; a pointer is moved within
onmouseout | HTML: a script expression; a pointer is moved away
onmouseover | HTML: a script expression; a pointer is moved onto
onmouseup | HTML: script expression; a pointer button is released
onpagechange | JavaScript handler for call after the page is changed
page | If page >= 1 then it's a page number to show
pageIndexVar | Name of variable in request scope containing index of active page
pagesVar | Name of variable in request scope containing number of pages
process | Id['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
rendered | If "false", this component is not rendered
renderIfSinglePage | If renderIfSinglePage is "true" then datascroller is displayed on condition that the data hold on one page. Default value is "true".
requestDelay | Attribute 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
reRender | Id['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
scrollerListener | MethodBinding representing an action listener method that will be notified after scrolling
selectedStyle | Corresponds to the HTML style attribute for the selected cell on scroller
selectedStyleClass | Corresponds to the HTML class attribute for the selected cell on scroller
status | ID (in format of call UIComponent.findComponent()) of Request status component
stepControls | The attribute specifies the visibility of stepControls. Possible values are: "show" (controls are always visible ). "hide" (controls are hidden. "auto" (unnecessary controls are hidden). Default value is "show".
style | CSS style(s) is/are to be applied when this component is rendered
styleClass | Corresponds to the HTML class attribute
tableStyle | CSS style(s) is/are to be applied to outside table when this component is rendered
tableStyleClass | Space-separated list of CSS style class(es) that are be applied to outside table of this component
timeout | Response waiting time on a particular request. If a response is not received during this time, the request is aborted
value | The current value for this component

Table 6.116. Component identification parameters

Name | Value
--- | ---
component-type | org.richfaces.Datascroller
component-class | org.richfaces.component.html.HtmlDatascroller
component-family | org.richfaces.Datascroller
renderer-type | org.richfaces.DataScrollerRenderer
tag-class | org.richfaces.taglib.DatascrollerTag

### 6.32.3. Creating the Component with a Page Tag

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

Example:

    ...

        <h:dataTable id="table">

            ...

        </h:dataTable>

        ...

        <rich:datascroller for="table"/>

    ...

### 6.32.4. Creating the Component Dynamically Using Java

Example:

    import org.richfaces.component.html.HtmlDatascroller;

    ...

    HtmlDatascroller myScroll = new HtmlDatascroller();

    ...

### 6.32.5. Details of Usage

The <rich:datascroller> component provides table scrolling functionalitity the same as TOMAHAWK scroller but with Ajax requests usage.

The component should be placed into footer of the parent table or be bound to it with the "for" attribute. Note, that "for" is evaluated on view build, not on view render, that is why it will ignore JSTL tags.

The table should also have the defined "rows" attribute limiting the quantity of inputted table rows.

The scroller could limit the maximum quantity of rendered links on the table pages with the help of the "maxPages" attribute.

Component provides two controllers groups for switching:

- Page numbers for switching onto a particular page

- The controls of fast switching: "first", "last", "next", "previous", "fastforward", "fastrewind"

The controls of fast switching are created adding the facets component with the corresponding name:

Example:

     ...

        <rich:datascroller for="table" maxPages="10">

            <f:facet name="first">

                <h:outputText value="First"/>

            </f:facet>

            <f:facet name="last">

                <h:outputText value="Last"/>

            </f:facet>

        </rich:datascroller>

    ...

Figure 6.33. <rich:datascroller> controls of fast switching

The screenshot shows one controller from each group.

There are also facets used to create the disabled states: `"first_disabled",` `"last_disabled",` `"next_disabled",` `"previous_disabled",` `"fastforward_disabled",` `"fastrewind_disabled"`.

For the `"fastforward"/"fastrewind"` controls customization the additional "fastStep" attribute is used. The attribute indicates pages quantity to switch onto when fast scrolling is used.

The "page" is a value-binding attribute used to define and save current page number. The example is placed below.

Example:

    ...

    <h:form id="myForm">

        <rich:dataTable id="carList" rows="7" value="#{dataTableScrollerBean.allCars}" var="category">

            <f:facet name="header">

                <rich:columnGroup>

                    <h:column>

                        <h:outputText value="Make" />

                    </h:column>

                    <h:column>

                        <h:outputText value="Model" />

                    </h:column>

                    <h:column>

                        <h:outputText value="Price" />

                    </h:column>

                </rich:columnGroup>

            </f:facet>

            <h:column>

                <h:outputText value="#{category.make}" />

            </h:column>

            <h:column>

                <h:outputText value="#{category.model}" />

            </h:column>

            <h:column>

                <h:outputText value="#{category.price}" />

            </h:column>

        </rich:dataTable>

        <rich:datascroller id="sc2" for="carList" reRender="sc1" maxPages="7" page="#{dataTableScrollerBean.scrollerPage}" />

        <h:panelGrid>

            <h:panelGroup>

                <h:outputText value="Set current page number:" />

                <h:inputText value="#{dataTableScrollerBean.scrollerPage}" id="sc1" size="1"/>

                <h:commandButton value="Set" />

            </h:panelGroup>

        </h:panelGrid>

    </h:form>

    ...

In the example above you can enter the page number you want and set it by clicking on the <h:commandButton> . By the way, if you use <rich:datascroller> page links the input field rerenders and current page number changes.

This is a result:

Figure 6.34. The "page" attribute usage

The "pageIndexVar" and "pagesVar" attributes define a request scope variables and provide an ability to show the current page and the number of pages in the <rich:datascroller> .

These attributes are used for definition the names of variables, that is used in the facet with name "pages" . An example can be found below:

Example:

    ...

    <h:form>

        <rich:dataTable value="#{capitalsBean.capitals}" var="cap" rows="5">

            <rich:column>

                <h:outputText value="#{cap.name}" />

            </rich:column>

            <f:facet name="footer">

                <rich:datascroller pageIndexVar="pageIndex" pagesVar="pages">

                    <f:facet name="pages">

                        <h:outputText value="#{pageIndex} / #{pages}" />

                    </f:facet>

                </rich:datascroller>

            </f:facet>

        </rich:dataTable>

    </h:form>

    ...

It's possible to insert optional separators between controls. For this purpose use a "controlSeparator" facet. An example is placed below.

     ...

          <f:facet name="controlSeparator">

                <h:graphicImage value="/image/sep.png"/>

          </f:facet>

    ...

Starting from 3.2.1 of RichFaces multiple <rich:datascroller> instances behavior and page bindings are corrected. Incorrect page after model changes handling is added. Phase Listener called before RenderResponce scans the page for the <rich:datascroller> and performs the following operations:

- Checks if the <rich:datascroller> is rendered. (If the checking generates an exception, the <rich:datascroller> is considered to be not rendered )

- If the <rich:datascroller> is rendered - the table to which the <rich:datascroller> is attached gets the value of the page attribute of <rich:datascroller> .

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

## Note:

Make sure, that all <rich:datascroller> components, defined for a table, have same values for "pages" attributes. The page, specified in the last "page" , will be rendered in browser.

### 6.32.6. Look-and-Feel Customization

For skinnability implementation, the components use a style class redefinition method. Default style classes are mapped on skin parameters.

There are two ways to redefine the appearance of all <rich:datascroller> components at once:

- Redefine the corresponding skin parameters

- Add to your style sheets style classes used by a <rich:datascroller> component

### 6.32.7. Skin Parameters Redefinition

Table 6.117. Skin parameters redefinition for a wrapper element

Skin parameters | CSS properties
--- | ---
tableBackgroundColor | background-color
panelBorderColor | border-color

Table 6.118. Skin parameters redefinition for a button

Skin parameters | CSS properties
--- | ---
additionalBackgroundColor | background-color
panelBorderColor | border-color
generalFamilyFont | font-family
generalSizeFont | font-size

Table 6.119. Skin parameters redefinition for an active button

Skin parameters | CSS properties
--- | ---
generalTextColor | border-top-color
generalTextColor | color
generalFamilyFont | font-family
generalSizeFont | font-size

Table 6.120. Skin parameters redefinition for an inactive button

Skin parameters | CSS properties
--- | ---
headerBackgroundColor | border-top-color
headerBackgroundColor | color
generalFamilyFont | font-family
generalSizeFont | font-size

### 6.32.8. Definition of Custom Style Classes

On the screenshot there are classes names that define styles for component elements.

Figure 6.35. Style classes

Table 6.121. Classes names that define a component appearance

Class name | Description
--- | ---
rich-datascr | Defines styles for a wrapper <div> element of a datascroller
rich-dtascroller-table | Defines styles for a wrapper table element of a datascroller
rich-datascr-button | Defines styles for a button
rich-datascr-ctrls-separator | Defines styles for a separator between buttons

Table 6.122. Classes names that define a buttons appearance

Class name | Description
--- | ---
rich-datascr-act | Defines styles for an active button
rich-datascr-inact | Defines styles for an inactive button
rich-datascr-button-dsbld | Defines styles for a disabled button

In order to redefine styles for all <rich:datascroller> components on a page using CSS, it's enough to create classes with the same names (possible classes could be found in the table above) and define necessary properties in them. An example is placed below:

Example:

    ...

    .rich-datascr-button{

        color: #CD6600;

    }

    ...

This is a result:

Figure 6.36. Redefinition styles with predefined classes

In the example an input text font style was changed.

Also it's possible to change styles of particular <rich:datascroller> component. In this case you should create own style classes and use them in corresponding <rich:datascroller> styleClass attributes. An example is placed below:

Example:

    ...

    .myClass{

        background-color: #C6E2FF;

    }

    ...

The "styleClass" attribute for <rich:datascroller> is defined as it's shown in the example below:

Example:

    <rich:datascroller ... selectedStyleClass="myClass"/>

This is a result:

Figure 6.37. Redefinition styles with own classes and styleClass attributes

As it could be seen on the picture above, background color of the selected cell on scroller was changed.

### 6.32.9. Relevant Resources Links

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

The solution about how to do correct pagination using datascroller (load a part of data from database) can be found on the RichFaces Users Forum.

How to use <rich:dataTable> and <rich:datascroller> in a context of Extended Data Model see here.

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