Checking whether a user already exists in drupal

Question

When a user enters his login information and hits submit, i want to check if the user already exists or not. So, i have the following two questions 1. Which hook is needed to be implemented , for the case when user hits the submit button on the login form. I need the username entered by the user. 2. How to check if a user already exists in drupal or not programmatically ?

Some sample code would be really appreciated. Please help.

Thank You.

score 22 · Answer 1 · answered Sep 28 '12 at 07:18

22

Drupal 7 provides a function to get a user object by name :

$user = user_load_by_name($name);
if(!$user){
    // User doesn't exist
} 
else {
    // User exists
}

http://api.drupal.org/api/drupal/modules%21user%21user.module/function/user_load_by_name/7

answered Sep 28 '12 at 07:18

Mika Andrianarijaona

1,619
17
29

1

This is a heavy-handed solution as it loads the entire user object, just to validate the existence of a user by name. Also, if you're loading a user, do not use a variable named `$user` as it could easily be confused with the `global $user` which is the current user account. – Christopher Feb 13 '14 at 04:39
you can also use `user_load_by_mail` in case you're searching by mail: https://api.drupal.org/api/drupal/modules!user!user.module/function/user_load_by_mail/7 – asiviero Mar 27 '15 at 13:32

googletorp · Answer 2 · 2014-07-30T14:01:23.063

12

This can be done with hook_form_alter:

function module_(&$form, &$form_state, $form_id) {
  $user_login_forms = array('user_login', 'user_login_block');
  if (in_array($form_id, $user_login_forms)) {
    $form['#validate'][] = 'my_validate_function';
  }
}

function my_validate_function(&$form, &$form_state) {
  $name = $form_state['values']['name'];
  // Drupal 6:
  if (!db_result(db_query("SELECT COUNT(*) FROM {users} WHERE name = '%s';", $name))) {
    // User doesn't exist
  }
  // Drupal 7:
  if (!db_query("SELECT COUNT(*) FROM {users} WHERE name = :name;", array(':name' => $name))->fetchField()) {
    // User doesn't exist
   }
}

It's better to query the DB directly in this case than than using user_load as it hooks into other modules as well.

edited Jul 30 '14 at 14:01

answered May 10 '10 at 15:30

googletorp

33,075
15
67
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1

I'd forgotten you could do that with `hook_form_alter`! Kudos! Deleting my answer. – ceejayoz May 10 '10 at 16:54
This does not work for Drupal 7. This does: `$result = db_query("SELECT COUNT(*) FROM {users} WHERE uid = :uid", array(':uid' => $uid))->fetchField(); if ($result == 0) { // User doesn't exist return FALSE; } return TRUE;` – DrCord Jul 29 '14 at 22:50

score 3 · Answer 3 · answered Jun 27 '11 at 11:57

3

In Drupal 7, substitute for this in the validation function:

if (!db_query("SELECT COUNT(*) FROM {users} WHERE name = :name", array(':name' => $name))->fetchField()) {
  // User doesn't exist
}

answered Jun 27 '11 at 11:57

Arla

31
1

score 1 · Answer 4 · answered Mar 24 '14 at 12:18

1

I realize this is almost 2 years old, but user_authenticate does this nicely.

$existing_user = user_authenticate($name,$password);
if($existing_user)
  // user exists
else
  // user doesn't exist

Hope this helps someone else.

answered Mar 24 '14 at 12:18

dawoodman71

395
4
16

3

this needs the password, this is a bad answer. – DrCord Jul 29 '14 at 21:58
1

If the user is entering a username and password why would this be a bad solution? The password isn't getting displayed and I'm simply using the password that was given. Am I missing something? – dawoodman71 Oct 24 '14 at 13:08

score 1 · Answer 5 · answered Sep 15 '15 at 11:01

1

You can try to look on these 2 modules for inspiration: friendly_register and username_check.

answered Sep 15 '15 at 11:01

Jasom Dotnet

1,225
12
17

Checking whether a user already exists in drupal

5 Answers5