java.lang.Object
- org.apache.velocity.tools.generic.SafeConfig
- - org.apache.velocity.tools.view.PagerTool

Direct Known Subclasses:: AbstractSearchTool

@DefaultKey("pager")
@InvalidScope({"application","session"})
public class PagerTool
extends org.apache.velocity.tools.generic.SafeConfig

View tool for doing request-based pagination of items in an a list.

Usage:
To use this class, you typically push a List of items to it by putting it in the request attributes under the value returned by getNewItemsKey() (default is "new.items"). You can also set the list of items to be paged in a subclass using the setItems(List) method, or you can always set the item list at another point (even from within the template). This need only happen once per session if a session is available, but the item list can be (re)set as often as you like.

Here's an example of how your subclass would be used in a template:

   #if( $pager.hasItems() )
   Showing $!pager.pageDescription<br>
     #set( $i = $pager.index )
     #foreach( $item in $pager.page )
       ${i}. $!item <br>
       #set( $i = $i + 1 )
     #end
     <br>
     #if ( $pager.pagesAvailable > 1 )
       #set( $pagelink = $link.self.param("show",$!pager.itemsPerPage) )
       #if( $pager.prevIndex )
           <a href="$pagelink.param('index',$!pager.prevIndex)">Prev</a>
       #end
       #foreach( $index in $pager.slip )
         #if( $index == $pager.index )
           <b>$pager.pageNumber</b>
         #else
           <a href="$pagelink.param('index',$!index)">$!pager.getPageNumber($index)</a>
         #end
       #end
       #if( $pager.nextIndex )
           <a href="$pagelink.param('index',$!pager.nextIndex)">Next</a>
       #end
     #end
   #else
   No items in list.
   #end

The output of this might look like:

   Showing 1-5 of 8<br>
   1. foo<br>
   2. bar<br>
   3. blah<br>
   4. woogie<br>
   5. baz<br><br>
   <b>1</b> <a href="">2</a> <a href="">Next</a>

Example tools.xml configuration:

 <tools>
   <toolbox scope="request">
     <tool class="org.apache.velocity.tools.view.PagerTool"/>
   </toolbox>
 </tools>

Since:: VelocityTools 2.0
Version:: $Revision$ $Date$
Author:: Nathan Bubna

Field Summary

Fields
Modifier and Type	Field	Description
`static java.lang.String`	`DEFAULT_INDEX_KEY`
`static int`	`DEFAULT_ITEMS_PER_PAGE`	the default number of items shown per page
`static java.lang.String`	`DEFAULT_ITEMS_PER_PAGE_KEY`
`static java.lang.String`	`DEFAULT_NEW_ITEMS_KEY`
`static int`	`DEFAULT_SLIP_SIZE`	the default max number of page indices to list
`static java.lang.String`	`DEFAULT_SLIP_SIZE_KEY`
`protected javax.servlet.http.HttpSession`	`session`
`protected static java.lang.String`	`STORED_ITEMS_KEY`	the key under which items are stored in session

Fields inherited from class org.apache.velocity.tools.generic.SafeConfig
LOCK_CONFIG_KEY, log, LOGGER_NAME_KEY, SAFE_MODE_KEY, USE_CLASS_LOGGER_KEY

Constructor Summary

Constructors
Constructor Description

PagerTool()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`getCreateSession()`
`java.lang.Integer`	`getFirstIndex()`	Returns the index of the first item on the current page of results (as determined by the current index, items per page, and the number of items).
`int`	`getIndex()`	Returns the current search result index.
`java.lang.String`	`getIndexKey()`
`java.util.List`	`getItems()`	Returns the item list.
`int`	`getItemsPerPage()`	Returns the set number of items to be displayed per page of items
`java.lang.String`	`getItemsPerPageKey()`
`java.lang.Integer`	`getLastIndex()`	Returns the index of the last item on the current page of results (as determined by the current index, items per page, and the number of items).
`java.lang.String`	`getNewItemsKey()`
`java.lang.Integer`	`getNextIndex()`	Returns the index for the next page of items (as determined by the current index, items per page, and the number of items).
`java.util.List`	`getPage()`	Returns the current "page" of search items.
`java.lang.String`	`getPageDescription()`	Returns a description of the current page.
`java.lang.Integer`	`getPageNumber()`	Returns the "page number" for the current index.
`java.lang.Integer`	`getPageNumber(int i)`	Returns the "page number" for the specified index.
`int`	`getPagesAvailable()`	Returns the number of pages that can be made from this list given the set number of items per page.
`java.lang.Integer`	`getPrevIndex()`	Return the index for the previous page of items (as determined by the current index, items per page, and the number of items).
`java.util.List`	`getSlip()`	Returns a Sliding List of Indices for Pages of items.
`int`	`getSlipSize()`	Returns the number of result page indices `getSlip()` will return per request (if available).
`java.lang.String`	`getSlipSizeKey()`
`protected java.util.List`	`getStoredItems()`	Retrieves stored search items (if any) from the user's session attributes.
`int`	`getTotal()`	Returns the total number of items available.
`boolean`	`hasItems()`	Checks whether or not the result list is empty.
`void`	`reset()`	Sets the item list to null, page index to zero, and items per page to the default.
`void`	`setCreateSession(boolean createSession)`
`void`	`setIndex(int index)`	Sets the index of the first result in the current page
`void`	`setIndexKey(java.lang.String key)`
`void`	`setItems(java.util.List items)`	Sets the List to page through.
`void`	`setItemsPerPage(int itemsPerPage)`	Sets the number of items returned in a page of items
`void`	`setItemsPerPageKey(java.lang.String key)`
`void`	`setNewItemsKey(java.lang.String key)`
`void`	`setRequest(javax.servlet.http.HttpServletRequest request)`	Initializes this tool with the specified `HttpServletRequest`.
`void`	`setSlipSize(int slipSize)`	Sets the number of result page indices for `getSlip()` to list.
`void`	`setSlipSizeKey(java.lang.String key)`
`protected void`	`setStoredItems(java.util.List items)`	Stores current search items in the user's session attributes (if one currently exists) in order to do efficient result pagination.
`void`	`setup(javax.servlet.http.HttpServletRequest request)`	Sets the index, itemsPerPage, and/or slipSize if they are set in the request parameters.

Methods inherited from class org.apache.velocity.tools.generic.SafeConfig
configure, configure, getLog, initLogger, isConfigLocked, isSafeMode, setLockConfig, setSafeMode

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - DEFAULT_NEW_ITEMS_KEY
```
public static final java.lang.String DEFAULT_NEW_ITEMS_KEY
```
    See Also:
    
    Constant Field Values
  - DEFAULT_INDEX_KEY
```
public static final java.lang.String DEFAULT_INDEX_KEY
```
    See Also:
    
    Constant Field Values
  - DEFAULT_ITEMS_PER_PAGE_KEY
```
public static final java.lang.String DEFAULT_ITEMS_PER_PAGE_KEY
```
    See Also:
    
    Constant Field Values
  - DEFAULT_SLIP_SIZE_KEY
```
public static final java.lang.String DEFAULT_SLIP_SIZE_KEY
```
    See Also:
    
    Constant Field Values
  - DEFAULT_ITEMS_PER_PAGE
```
public static final int DEFAULT_ITEMS_PER_PAGE
```
    the default number of items shown per page
    
    See Also:
    
    Constant Field Values
  - DEFAULT_SLIP_SIZE
```
public static final int DEFAULT_SLIP_SIZE
```
    the default max number of page indices to list
    
    See Also:
    
    Constant Field Values
  - STORED_ITEMS_KEY
```
protected static final java.lang.String STORED_ITEMS_KEY
```
    the key under which items are stored in session
  - session
```
protected javax.servlet.http.HttpSession session
```
- Constructor Detail
  - PagerTool
```
public PagerTool()
```
- Method Detail
  - setRequest
```
public void setRequest(javax.servlet.http.HttpServletRequest request)
```
    Initializes this tool with the specified HttpServletRequest. This is required for this tool to operate and will throw a NullPointerException if this is not set or is set to null.
    
    Parameters:
    
    request - servlet request
  - setup
```
public void setup(javax.servlet.http.HttpServletRequest request)
```
    Sets the index, itemsPerPage, and/or slipSize *if* they are set in the request parameters. Likewise, this will set the item list to be paged *if* there is a list pushed into the request attributes under the getNewItemsKey().
    
    Parameters:
    
    request - the current HttpServletRequest
  - setNewItemsKey
```
public void setNewItemsKey(java.lang.String key)
```
  - getNewItemsKey
```
public java.lang.String getNewItemsKey()
```
  - setIndexKey
```
public void setIndexKey(java.lang.String key)
```
  - getIndexKey
```
public java.lang.String getIndexKey()
```
  - setItemsPerPageKey
```
public void setItemsPerPageKey(java.lang.String key)
```
  - getItemsPerPageKey
```
public java.lang.String getItemsPerPageKey()
```
  - setSlipSizeKey
```
public void setSlipSizeKey(java.lang.String key)
```
  - getSlipSizeKey
```
public java.lang.String getSlipSizeKey()
```
  - setCreateSession
```
public void setCreateSession(boolean createSession)
```
  - getCreateSession
```
public boolean getCreateSession()
```
  - reset
```
public void reset()
```
    Sets the item list to null, page index to zero, and items per page to the default.
  - setItems
```
public void setItems(java.util.List items)
```
    Sets the List to page through.
    
    Parameters:
    
    items - - the List of items to be paged through
  - setIndex
```
public void setIndex(int index)
```
    Sets the index of the first result in the current page
    
    Parameters:
    
    index - the result index to start the current page with
  - setItemsPerPage
```
public void setItemsPerPage(int itemsPerPage)
```
    Sets the number of items returned in a page of items
    
    Parameters:
    
    itemsPerPage - the number of items to be returned per page
  - setSlipSize
```
public void setSlipSize(int slipSize)
```
    Sets the number of result page indices for getSlip() to list. (for google-ish result page links).
    
    Parameters:
    
    slipSize - - the number of result page indices to list
    
    See Also:
    
    getSlip()
  - getItemsPerPage
```
public int getItemsPerPage()
```
    Returns the set number of items to be displayed per page of items
    
    Returns:
    
    current number of items shown per page
  - getSlipSize
```
public int getSlipSize()
```
    Returns the number of result page indices getSlip() will return per request (if available).
    
    Returns:
    
    the number of result page indices getSlip() will try to return
  - getIndex
```
public int getIndex()
```
    Returns the current search result index.
    
    Returns:
    
    the index for the beginning of the current page
  - hasItems
```
public boolean hasItems()
```
    Checks whether or not the result list is empty.
    
    Returns:
    
    true if the result list is not empty.
  - getItems
```
public java.util.List getItems()
```
    Returns the item list. This is guaranteed to never return null.
    
    Returns:
    
    List of all the items
  - getLastIndex
```
public java.lang.Integer getLastIndex()
```
    Returns the index of the last item on the current page of results (as determined by the current index, items per page, and the number of items). If there is no current page, then null is returned.
    
    Returns:
    
    index for the last item on this page or null if none exists
    
    Since:
    
    VelocityTools 1.3
  - getNextIndex
```
public java.lang.Integer getNextIndex()
```
    Returns the index for the next page of items (as determined by the current index, items per page, and the number of items). If no "next page" exists, then null is returned.
    
    Returns:
    
    index for the next page or null if none exists
  - getFirstIndex
```
public java.lang.Integer getFirstIndex()
```
    Returns the index of the first item on the current page of results (as determined by the current index, items per page, and the number of items). If there is no current page, then null is returned. This is different than getIndex() in that it is adjusted to fit the reality of the items available and is not a mere accessor for the current, user-set index value.
    
    Returns:
    
    index for the first item on this page or null if none exists
    
    Since:
    
    VelocityTools 1.3
  - getPrevIndex
```
public java.lang.Integer getPrevIndex()
```
    Return the index for the previous page of items (as determined by the current index, items per page, and the number of items). If no "next page" exists, then null is returned.
    
    Returns:
    
    index for the previous page or null if none exists
  - getPagesAvailable
```
public int getPagesAvailable()
```
    Returns the number of pages that can be made from this list given the set number of items per page.
    
    Returns:
    
    number of available pages
  - getPage
```
public java.util.List getPage()
```
    Returns the current "page" of search items.
    
    Returns:
    
    a List of items for the "current page"
  - getPageNumber
```
public java.lang.Integer getPageNumber(int i)
```
    Returns the "page number" for the specified index. Because the page number is used for the user interface, the page numbers are 1-based.
    
    Parameters:
    
    i - the index that you want the page number for
    
    Returns:
    
    the approximate "page number" for the specified index or null if there are no items
  - getPageNumber
```
public java.lang.Integer getPageNumber()
```
    Returns the "page number" for the current index. Because the page number is used for the user interface, the page numbers are 1-based.
    
    Returns:
    
    the approximate "page number" for the current index or null if there are no items
  - getTotal
```
public int getTotal()
```
    Returns the total number of items available.
    
    Returns:
    
    number of items
    
    Since:
    
    VelocityTools 1.3
  - getPageDescription
```
public java.lang.String getPageDescription()
```
    Returns a description of the current page. This implementation displays a 1-based range of result indices and the total number of items. (e.g. "1 - 10 of 42" or "7 of 7") If there are no items, this will return "0 of 0".
    
    Sub-classes may override this to provide a customized description (such as one in another language).
    
    Returns:
    
    a description of the current page
  - getSlip
```
public java.util.List getSlip()
```
    Returns a Sliding List of Indices for Pages of items.
    Essentially, this returns a list of item indices that correspond to available pages of items (as based on the set items-per-page). This makes it relativly easy to do a google-ish set of links to available pages.
    
    Note that this list of Integers is 0-based to correspond with the underlying result indices and not the displayed page numbers (see getPageNumber(int)).
    
    Returns:
    
    List of Integers representing the indices of result pages or empty list if there's one or less pages available
  - getStoredItems
```
protected java.util.List getStoredItems()
```
    Retrieves stored search items (if any) from the user's session attributes.
    
    Returns:
    
    the List retrieved from memory
  - setStoredItems
```
protected void setStoredItems(java.util.List items)
```
    Stores current search items in the user's session attributes (if one currently exists) in order to do efficient result pagination.
    Override this to store search items somewhere besides the HttpSession or to prevent storage of items across requests. In the former situation, you must also override getStoredItems().
    
    Parameters:
    
    items - the List to be stored

Class PagerTool

Field Summary

Fields inherited from class org.apache.velocity.tools.generic.SafeConfig

Constructor Summary

Method Summary

Methods inherited from class org.apache.velocity.tools.generic.SafeConfig

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_NEW_ITEMS_KEY

DEFAULT_INDEX_KEY

DEFAULT_ITEMS_PER_PAGE_KEY

DEFAULT_SLIP_SIZE_KEY

DEFAULT_ITEMS_PER_PAGE

DEFAULT_SLIP_SIZE

STORED_ITEMS_KEY

session

Constructor Detail

PagerTool

Method Detail

setRequest

setup

setNewItemsKey

getNewItemsKey

setIndexKey

getIndexKey

setItemsPerPageKey

getItemsPerPageKey

setSlipSizeKey

getSlipSizeKey

setCreateSession

getCreateSession

reset

setItems

setIndex

setItemsPerPage

setSlipSize

getItemsPerPage

getSlipSize

getIndex

hasItems

getItems

getLastIndex

getNextIndex

getFirstIndex

getPrevIndex

getPagesAvailable

getPage

getPageNumber

getPageNumber

getTotal

getPageDescription

getSlip

getStoredItems

setStoredItems