How to check for existing user on creating a new one?

There's a missing condition in the user integration. I have it in code, and will create a patch sometime today. Pretty straightforward. My code checks by email address.

Perhaps a view of email addresses loaded into a list that you can loop over, or using profile2 load entity by field, or wjaspers way.

Hi, I have the same problem, the only difference is that I create users when they post a comment.
So I tried this data comparison:

$enbase='';
$courrier = $comment->mail;  // email from comment author, that is going to be used for account creation 
if (db_result(db_query("SELECT * FROM `users` WHERE `mail` LIKE '" . $courrier . "';"))) {
$enbase = $courrier;  //if user email already exists in DB, pass this email value to the $enbase variable
  }
return ($enbase);

So if the user email is already in the database, it will be returned and compared to the email, and therefore there will be no new account creation.

Unfortunately, I'm a PHP newbie, and I get a blank page here... Any suggestion will be warmly welcomed!

These are related:

• #1281466: Lazy registration / Post content first then register user
• Auto User
• Inline Registration

Thanks for your suggestions, but I'm actually looking for the specific piece of code to check if the user email already exists in the database.
So then I have tried this code, where $courrier is the email variable:

if (!db_query("SELECT COUNT(*) FROM {users} WHERE mail = :  $courrier ", array(':name' => $courrier))->fetchField()) {
  echo ("Email doesn't exist");
} 

I have this PDO error:
PDOException : SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '@example.com' at line 1: SELECT COUNT(*) FROM {users} WHERE mail = test@example.com ; Array ( [mail] => test@example.com ) dans eval() (ligne 11 dans /.../sites/all/modules/rules/modules/php.eval.inc(125) : eval()'d code).


What is wrong with my SQL Syntax here ?

Change this function and you'll have a special user-case exception of loading an entity if it already exists instead of failing to create a new one. User entities are the only ones to my knowledge with such an exception as name needing to be unique:

/**
 * Action: Create entities.
 */
function rules_action_entity_create($args, $element) {
  $values = array();
  foreach ($element->pluginParameterInfo() as $name => $info) {
    if ($name != 'type') {
      // Remove the parameter name prefix 'param_'.
      $values[substr($name, 6)] = $args[$name];
    }
  }
  try {
    // account for user entity exists error
    if (!($args['type'] == 'user' && $account = user_load_by_name($values['name']))) {
      $data = entity_property_values_create_entity($args['type'], $values);
    }
		else {
			$data = entity_metadata_wrapper('user', $account);
		}
    return array('entity_created' => $data);
  }
  catch (EntityMetadataWrapperException $e) {
    throw new RulesEvaluationException('Unable to create entity @type": ' . $e->getMessage(), array('@type' => $args['type']), $element);
  }
}

#6 works good. thx

The user_authenticate() function will return the UID if it exists and FALSE if it doesn't.

if(user_authenticate($name,$password)){
  // the user exists
}

There were a number of ways to solve this given above.

Perhaps a more general solution would be a new feature which could be used as a condition to find out if a specific entity (user in this case) with a specific property value (email in this case) already exists: #1777204: Add condition "Entity exists by property"

Please contribute to that issue if this would be useful to you.