PaginationHelper

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The PaginationHelper simplify the creation of paginated navigation on items.

Example

Suppose you have a set with 400 items:


public class MyController : SmartDispatcherController
{
    public void List()
    {
        PropertyBag["items"] = ObtainMyLargeCollection();
    }

    private IList ObtainMyLargeCollection()
    {
        ...
    }
}

With the PaginationHelper you can return a sliced representation of the collection:


public class MyController : SmartDispatcherController
{
    public void List()
    {
        PropertyBag["items"] = PaginationHelper.CreatePagination( ObtainMyLargeCollection(), 10 );
    }

    private IList ObtainMyLargeCollection()
    {
        ...
    }
}

The help will look for a page on Request.Params to define its starting index. The CreatePagination method returns a IPaginatedPage object which exposes several properties so you can build a nice pagination box:

FirstIndex
CurrentIndex
LastIndex
PreviousIndex
NextIndex
HasPrevious
HasNext
HasFirst
HasLast
FirstItem
LastItem
TotalItems

NVelocity example

This a snippet that renders the items and the pagination box:


#foreach($row in $items)
  <tr>
    <td>$row.Name</td>
    <td>$row.Email</td>
  </tr>
#end</table>

<div class="pagination">
<table width="100%" border="0">
  <tr>
  <td>Showing $items.FirstItem - $items.LastItem of $items.TotalItems</td>
  <td align="right">
#if($items.HasFirst) $PaginationHelper.CreatePageLink( 1, "first" ) #end
#if(!$items.HasFirst) first #end
#if($items.HasPrevious) | $PaginationHelper.CreatePageLink( $items.PreviousIndex, "prev" ) #end
#if(!$items.HasPrevious) | prev #end
#if($items.HasNext) | $PaginationHelper.CreatePageLink( $items.NextIndex, "next" ) #end
#if(!$items.HasNext) | next #end
#if($items.HasLast) | $PaginationHelper.CreatePageLink( $items.LastIndex, "last" ) #end
#if(!$items.HasLast) | last #end
  </td>
  </tr>
</table>
</div>

This will result in something like the following

Cached Pagination

The PaginationHelper has a cached version of its functionality. That allows the data source to be loaded and reused for a limited period of time. The cachekey must be carefully defined with the application semantics in mind. A bad cachekey might allow the data source to be shared by request from different users and with different data source search criterias (when the data source is the result of a search)

Suppose you have a form with many search criterias:

Your view will look something similar to this, and make sure to POST rather than GET:


<form id="search" method="post" action="$siteRoot/Cars/Search.aspx"
&lt;input id="make" type="text" size="14" name="make" /><br />
<input id="model" type="text" size="14" name="model" /><br />
<input id="year" type="text" size="14" name="year" /><br />
<input type="Submit" class="button" value="Search!" />

The pagination helper exposes a delegate that you will need to grab your search results. Pass it your method that handles the actual searching. Here is an example controller:


public class CarController : SmartDispatcherController
{
    private String make, model, year;
    
    public IList PerformSearch()
    {
        // Do your actual search
        
        return Car.FindByMakeModelYear(make, model, year);
    }
    
    public void Search(String make, String model, String year)
    {
        // create the pagination
        
        PropertyBag["Cars"] = PaginationHelper.CreateCachedPagination(
            "carssearchkey" + this.make + this.model + this.year, 
            5, new     DataObtentionDelegate(PerformSearch));
    }
}

Our resulting view, it is important that we expose our criteria to the view so the next/first/last/prev links can be correctly constructed and work properly:


<table cellpadding="4">
    <tr>
        <th>Make</th>
        <th>Model</th>
        <th>Year</th>
    </tr>
#foreach($Car in $Cars)
    <tr>
        <td>$!Car.Make</td>
        <td>$!Car.Model</td>
        <td>$!Car.Year</td>
    </tr>
#end
</table>
<div class="pagination" id="pagination">
<table width="90%" border="0">
    <tr>
        <td>Showing $Cars.FirstItem - $Cars.LastItem of $Cars.TotalItems</td>
        <td align="right">
        #if($Cars.HasFirst) 
            $PaginationHelper.CreatePageLink( 1, "first",null, "%{make=$make, model=$model,year=$year}" ) 
        #else
            first
        #end
        #if($Cars.HasPrevious) 
            | $PaginationHelper.CreatePageLink( $Cars.PreviousIndex, "prev",null, "%{make=$make,model=$model,year=$year}" ) 
        #else
            | prev 
        #end
        #if($Cars.HasNext) 
            | $PaginationHelper.CreatePageLink( $Cars.NextIndex, "next",null, "%{make=$make,model=$model,year=$year}" ) 
        #else
            | next
        #end
        #if($Cars.HasLast) 
            | $PaginationHelper.CreatePageLink( $Cars.LastIndex, "last",null, "%{make=$make,model=$model,year=$year}" ) 
        #else
            | last
        #end
        </td>
    </tr>
</table>
</div> <!-- end pagination -->

And how it looks:

API documentation

You may also consult the API documentation for the PaginationHelper.

Home

Castle Stronghold

Table of contents

PaginationHelper

Example

NVelocity example

Cached Pagination

API documentation