Drupal 11.3: Views Plugins Now Require Explicit Initial Preprocess Callbacks

Published in Drupal 11.3.x

Drupal 11.3 introduces a significant change in how preprocess functions for Views plugins are handled.
Previously, Drupal would implicitly discover functions like template_preprocess_HOOK() and apply them automatically to corresponding templates. This implicit behavior is now deprecated.

🔍 What Has Changed

• Views plugins can define a theme key in their plugin annotation.
• Earlier, Views would automatically create a theme hook and apply the corresponding template_preprocess_HOOK() function.
• Now, the system expects that an initial preprocess callback is explicitly defined in a specific method of a class, if such a method exists.

🧩 How Initial Preprocess Callbacks Work

The new convention places preprocess callbacks in a theme hooks class. The method name is generated by camel-casing the theme hook:

namespace Drupal\module_name\Hook;

class ModuleNameThemeHooks {

  public function preprocessCamelizedThemeHookName(array $variables) {
    // Your preprocessing logic here.
  }
}

Example:
If the module views_example_display defines a display plugin with:

theme: "views_display_example"

The corresponding initial preprocess method looks like this:

namespace Drupal\views_example_display\Hook;

class ViewsExampleDisplayThemeHooks {

  public function preprocessViewsDisplayExample(array $variables) {
    // Prepare variables for the template.
  }
}

⚙️ Service Registration

• The theme hooks class is automatically registered as a service if it contains at least one hook method.
• You can also register it explicitly in your services.yml:

services:
  Drupal\views_example_display\Hook\ViewsExampleDisplayThemeHooks:
    autowire: true

✅ Key Takeaways

• Implicit template_preprocess_HOOK() functions are deprecated.
• Use initial preprocess callbacks in a dedicated theme hooks class.
• This change affects module developers and themers who create custom Views plugins.
• Following this pattern ensures your preprocess logic is compatible with Drupal 12 and beyond.