How to use user table of a different database for WordPress users?

Question

I've a website currently running in CI and it has a user table. I'm making a WordPress website and need it to use the user table of the CI database for users to login in WordPress. How can I use only that table of different database? Both DBs are on same server. Also I have to differentiate between admin and normal users, as admins can enter the dashboard. I've tried this plugin but as soon as I activate this plugin my login page stops working and displays a 500 server error.

Answer 1

It might work to use a view as essentially a table alias, by doing the something like the following with the WordPress instance mysql database

 DROP TABLE wp_users
 CREATE VIEW wp_users AS SELECT * FROM CI.users;

However

• will probably need to tweak the view creation to map the columns
• the password encoding may well be different, so you might have hack WP core anyway to handle this
• you probably need to manually modify the wp_usermeta table to properly signify admins.

Answer 2

You don't need a plugin to make multiple db connections in CI. Just do this:

Connection 1 - /application/config/database.php

This is your default CI database config

$db['default']['hostname'] = 'DB_HOST';
$db['default']['username'] = 'DB_USER';
$db['default']['password'] = 'DB_PASSWORD';
$db['default']['database'] = 'DB_NAME';

$db['default']['dbdriver'] = 'mysql';
$db['default']['dbprefix'] = '';
$db['default']['pconnect'] = TRUE;
$db['default']['db_debug'] = TRUE;
$db['default']['cache_on'] = FALSE;
$db['default']['cachedir'] = '';
$db['default']['char_set'] = 'utf8';
$db['default']['dbcollat'] = 'utf8_general_ci';
$db['default']['swap_pre'] = '';
$db['default']['autoinit'] = TRUE;
$db['default']['stricton'] = FALSE;

Connection 2 - /application/config/database.php

Duplicate that chunk of code, renaming the $db['default'] with something like $db['secondary']

$db['secondary']['hostname'] = 'SECONDARY_DB_HOST';
$db['secondary']['username'] = 'SECONDARY_DB_USER';
$db['secondary']['password'] = 'SECONDARY_DB_PASSWORD';
$db['secondary']['database'] = 'SECONDARY_DB_NAME';

$db['secondary']['dbdriver'] = 'mysql';
$db['secondary']['dbprefix'] = '';
$db['secondary']['pconnect'] = TRUE;
$db['secondary']['db_debug'] = TRUE;
$db['secondary']['cache_on'] = FALSE;
$db['secondary']['cachedir'] = '';
$db['secondary']['char_set'] = 'utf8';
$db['secondary']['dbcollat'] = 'utf8_general_ci';
$db['secondary']['swap_pre'] = '';
$db['secondary']['autoinit'] = TRUE;
$db['secondary']['stricton'] = FALSE;

Initiate and use Connection 2

function getWordpressUsers() {

    $secondaryDb = $this->load->database('secondary', TRUE);

    $query = $secondaryDb->select('user_email, display_name')->get('wp_users');
    var_dump($query);

}

For more info about it, check this out: https://codeigniter.com/user_guide/database/connecting.html

Answer 3

It's not possible in Wordpress to have shared users between 2 separates installations on 2 separated databases.

It could be possible just by hardcoding:

1. hardcode WP_User class connect to other database and retrieve users from there
2. hardcode get_metadata() function, that for wp_usermeta table connect to other database and retrieve users from there

but mentioned solution is not recommended of course, because it's not updateproof.