Pass variable to field template from theme_preprocess_field()

Question

I'm stuck trying to pass variables from my theme_preprocess_field function to my template file. I want to have a variable for each of the fields I am printing out to my template.

I'm using the Paragraphs module in Drupal 7, so that might be throwing me off, but I feel like I'm really close. Here's a simple example:

Preprocess function in my template.php:

function merge_preprocess_field(&$variables) {
    $element = $variables['element'];
  if (isset($element['#field_name'])) {
    if ($element['#field_name'] == 'field_title') {
      $variables['test_title'] = $variables['items'][0]['#markup'];
    }
  }
}

The name of the template I am using is paragraphs-item--full-text.tpl.php.

field_title is the name of a field inside a paragraphs bundle called full-text.

Everything that I have read so far indicates that I should be able to access the $variables['test_title'] variable in my template this way:

<?php print render($test_title); ?>

It doesn't print, even after clearing the cache. It's even showing up in the array when I krumo($variables);. Am I missing something?

Answer 1

Ok, I figured this out. My preprocess function was for a field, but I was trying to access the variable in the wrong template. What I ended up doing was creating individual preprocess functions for each paragraphs-item, and preprocessing the variables in there.

First, I created a function that would allow me to create preprocess functions for entity types:

function merge_preprocess_entity(&$vars, $hook) {
  $function = 'merge_preprocess_' . $vars['entity_type'];
  if (function_exists($function)) {
    $function($vars, $hook);
  }
}

This allowed me to create a preprocess function for paragraphs items. Then I used this same idea to create preprocess functions for individual paragraphs items:

function merge_preprocess_paragraphs_item(&$vars, $hook) {
  $elements = $vars['elements'];

  $function = 'merge_preprocess_paragraphs_item__' . $elements['#bundle'];
  if (function_exists($function)) {
    $function($vars, $hook);
  }
}

Now I can set variables that are available in the paragraphs items templates, like so:

function merge_preprocess_paragraphs_item__smaller_full_width_text(&$vars, $hook) {

  if ($vars['content']['field_cta']) {

    $field_cta = !empty($vars['content']['field_cta'])? $vars['content']['field_cta'][0]['entity']['field_collection_item']: '';

    foreach ($field_cta as $field_cta) {

        // Make the CTA url available to the rest of the block
        $vars['content']['cta_url'] = $field_cta['field_link'][0]['#markup'];

        // Set character limit for CTA Text
        $vars['content']['cta_text'] = truncate_utf8($field_cta['field_link_text'][0]['#markup'], 24, TRUE, FALSE);

    }
  }
}