Hello

A Page Type has the following TextFields:
$Section1Heading
$Section2Heading
$Section3Heading
$Section4Heading
$Section5Heading

I want to be able to display the values of these fields in a template once they have been converted to lowercase and has all non-alphanumeric characters converted to hyphens.

So "What We Do" becomes "what-we-do" - and can be displayed in the template as such. This is so the converted string can be used as a div id for navigation purposes.

I can think of a number of different approaches but not sure which one to take.

Is there a correct or recommended approach for this sort of thing?

The way I would recommend is a custom getter on your page type. In 3.0 you can pass variables into methods so you only need to define the method once.

public function getFormattedSectionHeading($heading) {
$f = URLSegmentFilter::create();
$t = $f->filter($title);

return DBField::create('Text', $t);
}

Then use $FormattedSectionHeading($Heading) in your template.

You could also create a new DBField subclass and encapsulate this logic on the field type

<?php class MyFormattableVarchar extends Varchar {
public function AwesomeFormat($heading) {
$f = URLSegmentFilter::create();
$t = $f->filter($title);

return DBField::create('Text', $t);
}
}

Then using "Field" => "MyFormattableVarchar" will be possible in $db arrays and your templates will look like $Section1Heading.AwesomeFormat

Thank you for your time Will.

Here's the solution I went for:

/mysite/code/Model/TidyFormatVarchar.php

<?php

class TidyFormatVarchar extends Varchar {

  public function AnchorName() {
    $f = URLSegmentFilter::create();
    $t = $f->filter($this->value);
    return $t;
  }
}

/mysite/code/PageTypes/MyPage.php

class MyPage extends SiteTree {
  public static $db = array(
      'Section1Heading' => 'TidyFormatVarchar',
      'Section2Heading' => 'TidyFormatVarchar',
...

/themes/mytheme/templates/Layout/MyPage.php

<div id="$Section1Heading.AnchorName" class="section-1">

Just for reference, here's an alternative solution I use:

<?php

class StringFieldExtension extends Extension {

	public function CSSSafe() {
		return Convert::raw2url($this->owner->value);
	}

}

Apply the extension, either YAML:

StringField:
  extensions:
    - StringFieldExtension

or _config.php

Object::add_extension('StringField', 'StringFieldExtension');

Then in your templates you can use

<div id="$Section1Heading.CSSSafe" class="section-1">

Thank you for posting that up kinglozzer - it's tidier than the approach I used.

I like tidy.