Templates

Manipulating every Nth item in a <% control %> loop

Often you will want to manipulate every nth item inside a <% control %> loop. For example say you had a gallery and you wanted every 3rd image to start on a new line, you need to be able to test each item from the template to see if it is divisible by 3 and should therefore have the clear CSS class added to it.

Using iteratorPos % we can very easily achieve this. First we need to add the test function to the object we will be iterating through, so for example if you are iterating through a number of ImageItem DataObjects, we would add this function to our ImageItem class:
public function IsThird(){ return ($this->iteratorPos % 3) == 0; }

The % operator calculates the modulous or Remainder after dividing by the number that follows it (in this case 3). If there is a remainder then we know that the item is not divisible by 3 and so should not be cleared, but if the modulous is equal to 0 then we know it is divisible by 3 and should therefore clear a new line.

Working with banners

Submitted by Nick Jacobs.

Most of the sites I work on are for corporate/business clients and there is not typically a lot of fancy motion graphics going on. I do like to ensure there is some dynamic element going on, just to provide a bit of interest and one of the simplest ways to achieve this is by some variation of the random/rotating banners scenario. Of course this could equally apply to other parts of the page, not just banner graphics.

Over the course of a few projects, trawling the SS forums and hacking together my own interpretations, I have ended up with a few different ways of doing this in SilverStripe.

A random rotating banner

This function gets a set of random banners from a specified folder - in this case BannerImages
function RandomBanners(){ return DataObject::get('Image', 'ClassName <> "Folder" AND ParentID = (SELECT ID FROM File WHERE ClassName = "Folder" AND Name = "BannerImages")','RAND()','','5'); } 

Creating Previous and Next Buttons on a page

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.

Create an 'Edit this Page' link

For some sites you may want your client to be able to click a link on a particlar page and be taken strait to that page in the admin area. Here's what a link that does just that would look like:
<a href="admin/show/{$ID}" title="edit this page">Edit this page</a>

If you wanted this to only show up when a user is logged in you could use the CurrentMember call to check. So it would look like this:
<% if CurrentMember %> <a href="admin/show/{$ID}" title="edit this page">Edit this Page</a> <% end_if %>

You could also take this a step further and write a function in your page controller to check whether the current user has permission to access the CMS using Permission::check('CMS_ACCESS_CMSMain') call.

Resizing an image in a custom <img> tag

You can resize images from within the template quite easily. Using an image defined as $Image1 in the class this is how we would create a few different resizes of it.

<% control Image1 %> <% control CroppedImage(200,200) %> <img src="$URL" alt="A cropped image" /> <% end_control %> <% end_control %>