theme_hook_suggestions on custom theme?

Question

I have a module that implements HOOK_theme() to define a 'petition' theme like so:

function mymod_theme() {
  return [
    'petititon' => ['variables' => ['foo'=>NULL], 'template' => 'petition']
  ];
}

Which I then use like:

$some_render_array[] = [ '#theme' => 'petition', '#foo' => 'Bar' ];

Which is then rendered by a petition.tpl.php template file.

However, I would like to do this:

$some_render_array[] = [
  '#theme' => 'petition',
  '#theme_hook_suggestions' => ['petition__1'],
  '#foo' => 'Bar'
];

...and have it look for petition--1.tpl.php, in the same way you can for nodes, pages etc.

But this doesn't seem to work. Is it possible to have a theme that can take a template suggestion? I have a bunch of things to render which all require the same processing but use different templates.

Answer 1

To suggest specific templates you probably need to do it in your theme's template file, use the hook_preprocess_HOOK where the first hook is the name of your theme and seconde HOOK is either page to suggest a page template or node to suggest a node page.

Here's an example

/**
 * Implementation of hook_preprocess_HOOK().
 */
function mymodule_preprocess_page(&$variables){
  // change the condition to whatever you like
  if(isset($variables['node']) && arg(2) != 'edit')
    $variables['theme_hook_suggestions'][] = 'page__'. $variables['node']->type;
}