Package org.apache.velocity.tools.view

Class AbstractSearchTool

  • @DefaultKey("search")
@InvalidScope({"application","session"})
public abstract class AbstractSearchTool
extends PagerTool

    Abstract view tool for doing "searching" and robust pagination of search results. The goal here is to provide a simple and uniform API for "search tools" that can be used in velocity templates (or even a standard Search.vm template). In particular, this class provides good support for result pagination and some very simple result caching.

    Usage:
    To use this class, you must extend it and implement the executeQuery(Object) method.

    The setCriteria(Object) method takes an Object in order to allow the search criteria to meet your needs. Your criteria may be as simple as a single string, an array of strings, or whatever you like. The value passed into this method is that which will ultimately be passed into executeQuery(Object) to perform the search and return a list of results. A simple implementation might be like: 

     protected List executeQuery(Object crit)
 {
     return MyDbUtils.getFooBarsMatching((String)crit);
 }

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

       <form name="search" method="get" action="$link.setRelative('search.vm')">
     <input type="text"name="find" value="$!search.criteria">
     <input type="submit" value="Find">
   </form>
   #if( $search.hasItems() )
   Showing $!search.pageDescription<br>
     #set( $i = $search.index )
     #foreach( $item in $search.page )
       ${i}. $!item <br>
       #set( $i = $i + 1 )
     #end
     <br>
     #if ( $search.pagesAvailable > 1 )
       #set( $pagelink = $link.setRelative('search.vm').addQueryData("find",$!search.criteria).addQueryData("show",$!search.itemsPerPage) )
       #if( $search.prevIndex )
           <a href="$pagelink.addQueryData('index',$!search.prevIndex)">Prev</a>
       #end
       #foreach( $index in $search.slip )
         #if( $index == $search.index )
           <b>$search.pageNumber</b>
         #else
           <a href="$pagelink.addQueryData('index',$!index)">$!search.getPageNumber($index)</a>
         #end
       #end
       #if( $search.nextIndex )
           <a href="$pagelink.addQueryData('index',$!search.nextIndex)">Next</a>
       #end
     #end
   #elseif( $search.criteria )
   Sorry, no matches were found for "$!search.criteria".
   #else
   Please enter a search term
   #end

    The output of this might look like:

       <form method="get" action="">
    <input type="text" value="foo">
    <input type="submit" value="Find">
   </form>
   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="com.foo.tools.MySearchTool"/>
   </toolbox>
 </tools>
    Since:
    VelocityTools 2.0
    Version:
    $Revision$ $Date$
    Author:
    Nathan Bubna

    • Field Detail

      • DEFAULT_CRITERIA_KEY

        public static final java.lang.String DEFAULT_CRITERIA_KEY
        See Also:
        Constant Field Values

      • STORED_RESULTS_KEY

        protected static final java.lang.String STORED_RESULTS_KEY
        the key under which StoredResults are kept in session

    • Constructor Detail

      • AbstractSearchTool

        public AbstractSearchTool()

    • Method Detail

      • setup

        public void setup​(javax.servlet.http.HttpServletRequest request)
        Sets the criteria *if* it is set in the request parameters.
        Overrides:
        setup in class PagerTool
        Parameters:
        request - the current HttpServletRequest

      • setCriteriaKey

        public void setCriteriaKey​(java.lang.String key)

      • getCriteriaKey

        public java.lang.String getCriteriaKey()

      • reset

        public void reset()
        Sets the criteria and results to null, page index to zero, and items per page to the default.
        Overrides:
        reset in class PagerTool

      • setCriteria

        public void setCriteria​(java.lang.Object criteria)
        Sets the criteria for this search.
        Parameters:
        criteria - - the criteria used for this search

      • getCriteria

        public java.lang.Object getCriteria()
        Return the criteria object for this request. (for a simple search mechanism, this will typically be just a java.lang.String)
        Returns:
        criteria object

      • getItems

        public java.util.List getItems()
        Gets the results for the given criteria either in memory or by performing a new query for them. If the criteria is null, an empty list will be returned.
        Overrides:
        getItems in class PagerTool
        Returns:
        List of all items for the criteria

      • getStoredItems

        protected java.util.List getStoredItems()
        Description copied from class: PagerTool
        Retrieves stored search items (if any) from the user's session attributes.
        Overrides:
        getStoredItems in class PagerTool
        Returns:
        the List retrieved from memory

      • setStoredItems

        protected void setStoredItems​(java.util.List items)
        Description copied from class: PagerTool
        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().

        Overrides:
        setStoredItems in class PagerTool
        Parameters:
        items - the List to be stored

      • executeQuery

        protected abstract java.util.List executeQuery​(java.lang.Object criteria)
        Executes a query for the specified criteria.

        This method must be implemented! A simple implementation might be something like:

         protected List executeQuery(Object crit)
 {
     return MyDbUtils.getFooBarsMatching((String)crit);
 }
        Parameters:
        criteria - search criteria
        Returns:
        a List of results for this query

      • setStoredResults

        protected void setStoredResults​(AbstractSearchTool.StoredResults results)
        Stores current search results in the user's session attributes (if one currently exists) in order to do efficient result pagination.

        Override this to store search results somewhere besides the HttpSession or to prevent storage of results across requests. In the former situation, you must also override getStoredResults().

        Parameters:
        results - the AbstractSearchTool.StoredResults to be stored