Hook into a field's output? TextFormatters?

[owzim]

Hi,

I was wondering if it is possible to hook some logic into the output of a certain field. System wide, front- and backend. 

I'm thinking TextFormatters.

What I want for example is to:

echo $page->some_fancy_field;

And in the background it is making some very individual calculations and other fancy stuff with other fields of that same $page.

The field itself holds no actual value.

Possible?

[owzim]

OK, I am one step closer to what I want to achieve, still learning this hooking stuff.

I put everything into a module, and add a hook into the init() function:

$this->addHookAfter('FieldtypeText::formatValue', $this, 'myFormattedTextField');

public function myFormattedTextField($event) {

	$page = $event->arguments(0); 
	$field = $event->arguments(1); 
	$fieldValue = $event->arguments(2);
		
	if((string)$field->type === "FieldtypeText" && $field->name === "my_special_field") {	
		$event->return = $page->title + " - modified Page Title ftw";
	}
}

So here I have access to all field of the field's page, so I can fiddle around with that.

One thing that passed on by me is that all fields of that field's parent page have formatting off:

$page->some_field->of(true);

threw an error.

(edit: as Wanze stated it's $page->of(true), additionally I mixed something up)

The ultimate goal for me would be an extra field type, where I can set a custom php output via admin (like the PHP you can set as a selector for pages on a PageField).

If I am getting things wrong here, please let me know.

[Wanze]

As far as I know, you can't enable/disable outputFormatting on fields, but on pages.

Did you mean:

$page->of(true);

[owzim]

Wanze, yes my bad. I mixed something up. Edited it out my post. Everything is working as expected in that case.

[ryan]

if((string)$field->type === "FieldtypeText"

You can just do: if($field->type == 'FieldtypeText'. But it looks like you are intending to operate on the 'title' field? In that case, I think what you really want is FieldtypePageTitle. 

$event->return = $page->title + " - modified Page Title ftw";

The "+" won't concatenate strings in PHP. You want to use "." instead. 

With regard to everything else, it looks like you are on the right track. However, it might make more sense for you to just implement a Textformatter module instead, as this is exactly what they are designed for:

/site/modules/TextformatterOzwim.module

class TextformatterOwzim extends Textformatter {
  public static function getModuleInfo() {
    return array('title'=>'Ozwim','version'=>1,'summary'=>'Ozwim summary'); 
  }
  public function formatValue($page, $field, &$value) {
    $value .= "- modified page title FTW";
  }
} 

Once you've got that, install it and select it as the Textformatter for your page title field (or whatever field you want to apply it to). 

[owzim]

The "+" won't concatenate strings in PHP. You want to use "." instead.

I know, I was writing that on the fly into the comment box. That happens a lot to me when I am switching between JS and PHP =)

Thanks, I will definitely make use of the Textformatter version/

[Can]

For future reference, only for front end though (as far as I'm aware of, because you output it slightly differently) there's field rendering template files

https://processwire.com/blog/posts/more-repeaters-repeater-matrix-and-new-field-rendering/#processwire-3.0.5-introduces-field-rendering-with-template-files
https://processwire.com/blog/posts/processwire-3.0.7-expands-field-rendering-page-path-history-and-more/#field-rendering-with-template-files

they can be a nice alternative for textformatters at least front-end wise, and maybe easier for newcomers