Creating Previous and Next Buttons on a page

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28 June 2009 | Aram Balakjian | DataObjects, Templates | Supports v2.4, v2.3

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When you have a number of pages which follow on from one another you may find that asking a user to return to an index or select the next item from a side menu each time they want to progress is cumbersome. In this situation having previous and next buttons at the bottom of a page becomes very useful. In this snippet we'll add these buttons and also a counter to show the current page we are on and the total number of pages.

First add this function to your Page_Controller class:

    public function PrevNextPage($Mode = 'next') {
	  
	  if($Mode == 'next'){
	  	$Where = "ParentID = ($this->ParentID) AND Sort > ($this->Sort)";
		$Sort = "Sort ASC";
	  }
	  elseif($Mode == 'prev'){
	  	$Where = "ParentID = ($this->ParentID) AND Sort < ($this->Sort)";
		$Sort = "Sort DESC";
	  }
	  else{
	  	return false;
	  }
	  
	  return DataObject::get("SiteTree", $Where, $Sort, null, 1);
	  	
    }

Let's go through the function. First we pass in a string $Mode. This will be used to decide whether to return the previous or next page.

Then if we have passed in 'next' (the default) we setup the database criteria for that page, which is having the same parent ID and a sort value that is higher than the current page. We also set the database sort to arrange the pages by their Sort value in Ascending order. Otherwise if $Mode is 'prev' then we setup the criteria to fetch the previous page. If $Mode was not equal to either 'next' or 'prev' then we just return false.

Finally we do the database call and grab a single page using the criteria we set in the first part of the function and return the result.

Now we can use this function in our template like so:

<% control PrevNextPage(prev) %>
	  <a href="$Link" title="Go to $Title">&lt; previous page</a>	
<% end_control %>
<% control PrevNextPage(next) %>				
	  <a href="$Link" title="Go to $Title">next page &gt; </a>
<% end_control %>

By wrapping the links in <% control %> blocks instead of using $Variables, we prevent the link from being drawn if there is no page to go to.

Finally we can also add these functions to our Page_Controller to enable us to print the current page's number and the total number of pages:

public function NumberOfSiblings(){
	return DataObject::get("SiteTree","ParentID = ($this->ParentID)")->Count();
}
public function CurrentPageNumber(){
	return (DataObject::get("SiteTree","ParentID = ($this->ParentID) AND Sort <= ($this->Sort)")->Count());
}

And then in our template:

<p>Page $CurrentPage of $NoOfSiblings</p>

Thanks to Rick for suggesting this snippet!