Creating and using custom tokens in Drupal 7

This post outlines the steps required to create your own custom tokens in Drupal.

When writing the recent releases of the Copyright Block module, I used tokens to allow the user to edit and customise their copyright message and place the copyright_message:dates token in the desired position. When the block is rendered, the token is replaced by the necessary dates.

We will be using the fictional foo module to demonstrate this.

Requirements

Recommended

Implementing hook_token_info().

The first thing that we need to do is define the new token type and/or the token itself, along with it's descriptive text. To view the existing tokens and types, use dpm(token_get_info());, assuming that you have the Devel module installed.

/**
 * Implements hook_token_info().
 */
function foo_token_info() {
  $info = array();

  // Add any new tokens.
  $info['tokens']['foo']['bar'] = t('This is my new bar token within the foo type.');

  // Return them.
  return $info;
}

In this case, the token called bar resides within the foo group.

If I needed to add a new token within an existing token type, such as 'node', the syntax would be $info['tokens']['node']['bar'].

Implementing hook_tokens().

Now that the Token module is aware of our new token, we now need to determine what the token is replaced with. This is done using hook_tokens(). Here is the basic code needed for an implementation:

/**
 * Implements hook_tokens().
 */
function foo_tokens($type, $tokens, array $data = array(), array $options = array()) {
  $replacements = array();

  // Code goes here...

  // Return the replacements.
  return $replacements;
}

The first thing to check for is the type of token using an if() function, as this could be an existing type like 'node', 'user' or 'site', or a custom token type like 'foo'. Once we're sure that we're looking at the right type(s), we can use foreach ($tokens as $name => $original) to loop through each of the available tokens using a switch(). For each token, you can perform some logic to work out the replacement text and then add it into the replacements array using $replacements[$original] = $new;.

/**
 * Implements hook_tokens().
 */
function foo_tokens($type, $tokens, array $data = array(), array $options = array()) {
  $replacements = array();

  // The first thing that we're going to check for is the type of token - node,
  // user etc...
  if ($type == 'foo') {
    // Loop through each of the available tokens.
    foreach ($tokens as $name => $original) {
      // Find the desired token by name
      switch ($name) {
        case 'bar':
          $new = '';

          // Work out the value of $new...

          // Add the new value into the replacements array.
          $replacements[$original] = $new;
          break;
      }
    }
  }

  // Return the replacements.
  return $replacements;
}

Example

An example from Copyright Block module:

/**
 * Implements hook_tokens().
 */
function copyright_block_tokens($type, $tokens, array $data = array(), array $options = array()) {
  $replacements = array();

  if ($type == 'copyright_statement') {
    foreach ($tokens as $name => $original) {
      switch ($name) {
        case 'dates':
          $start_year = variable_get('copyright_block_start_year', date('Y'));
          $current_year = date('Y');

          $replacements[$original] = $start_year < $current_year ? $start_year . '-' . $current_year : $start_year;
          break;
      }
    }
  }

  return $replacements;
}

Using token_replace().

With everything defined, all that we now need to do is pass some text through the token_replace() function to replace it with the values defined within hook_token().

$a = t('Something');
$b = token_replace($a); // This would use any token type - node, user etc.
$c = token_replace($a, array('foo')); // This would only use foo tokens.

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About Oliver Davies

Oliver Davies is a Drupal Developer and Linux Systems Administrator. He is a Web Developer at the Drupal Association and also offers freelance development and consultancy services.