WP 3.1 – pg4wp – Cannot redeclare class wpdb

  • Resolved touisk

    (@touisk)


    14 years ago

    Hi,

    My blog was ok whith WordPress 3.0.4 and pg4wp 1.1.0 until I updated to wordpress 3.1 !

    PHP logs shows a PHP Fatal error:  Cannot redeclare class wpdb in /usr/share/wordpress/htdocs/wp-content/db.php(37) : eval()'d code on line 52

    In wordpress 3.0.5 the require_wp_db(); – call in the /wp-settings.php – is implemented in the file /wp-includes/functions.php which is :

    function require_wp_db() {
        global $wpdb;
        if ( file_exists( WP_CONTENT_DIR . '/db.php' ) )
                require_once( WP_CONTENT_DIR . '/db.php' );
        else
                require_once( ABSPATH . WPINC . '/wp-db.php' );
}

    The class wpdb – in /wp-includes/wp-db.php – is evaluated by the eval function in /wp-content/db.php file from pg4wp :

    eval( str_replace( array_keys($replaces), array_values($replaces), file_get_contents(ABSPATH.'/wp-includes/wp-db.php')));

    The evaluation is done after the replacement of MySQL names to postgres ones.

    But in WordPress 3.1, require_wp_db() function has moved into the file /wp-includes/load.php. The new implementation is :

    function require_wp_db() {
        global $wpdb;

        require_once( ABSPATH . WPINC . '/wp-db.php' );
        if ( file_exists( WP_CONTENT_DIR . '/db.php' ) )
                require_once( WP_CONTENT_DIR . '/db.php' );

        if ( isset( $wpdb ) )
                return;

        $wpdb = new wpdb( DB_USER, DB_PASSWORD, DB_NAME, DB_HOST );
}

    in those conditions; /wp-includes/wp-db.php is evaluated twice ! with the wp-content/db.php. The class wpdb can not be redeclared twice.

    My solution is to … come back. I simply re-implemented the WP 3.1 require_wp_db() function like this :

    function require_wp_db() {
        global $wpdb;

        if ( file_exists( WP_CONTENT_DIR . '/db.php' ) )
                require_once( WP_CONTENT_DIR . '/db.php' );
        else
                require_once( ABSPATH . WPINC . '/wp-db.php' );

        if ( isset( $wpdb ) )
                return;

        $wpdb = new wpdb( DB_USER, DB_PASSWORD, DB_NAME, DB_HOST );
}

    Hope, this could help …

Viewing 15 replies - 1 through 15 (of 16 total)

  • Thank you for your fine post touisk. You saved me lots of time.

    That illogical piece of code should have never made it into production! I hope it will be fixed in the next release.

    “Cannot redeclare class” suggests that the upgrade did not complete successfully. The answer is to not edit the core code but:

    – switc to the Twenty Ten theme by renaming your current theme’s folder in wp-content/themes using FTP or whatever file management application your host provides.

    – reset the plugins folder by FTP or phpMyAdmin.

    – re-upload all files & folders – except the wp-content folder – from a fresh download of WordPress.

    – re-run the upgrade manually using wp-admin/upgrade.php.

    After Your advice I have following error – it occures when I try to acces /my-wordpress/wp-admin page…

    Warning: pg_query() [function.pg-query]: No PostgreSQL link opened yet in /home/wordpress/www/wp-content/plugins/pg4wp/driver_pgsql.php on line 318

Warning: Cannot modify header information - headers already sent by (output started at /home/wordpress/www/wp-content/plugins/pg4wp/driver_pgsql.php:318) in /home/wordpress/www/wp-includes/pluggable.php on line 897

    help ??

    I still have this warning:
    “Warning: pg_query() [function.pg-query]: No PostgreSQL link opened yet in /home/wordpress/www/wp-content/plugins/pg4wp/driver_pgsql.php on line 318”
    and I don’t know what to do…
    accessing wp-admin is impossible. Do You have any advice?

    @bimki: do as touisk or esmi explained and all should work fine.

    @esmi: is it safe to update to 3.1.1 automatically this time (regardless of whether one has followed touisk solution and changed to core files, or your manual update)? I don’t know what caused the update to fail last time, but judging from the posts concerning this, it isn’t isolated to this thread… and it wouldn’t be nice if something similar happened again.

    @davorj – I’ve done it as touisk explained (I’ve changed implementation of require_wp_db function)…

    @bimki: Then I don’t know, sorry…

    @esmi: WordPress 3.1.1 still doesn’t auto-update well… I don’t think it has anything to do with the auto-update. When I compare my WordPress files with the original files after I auto-update, all are the same, except the ones in wp-content. So I don’t think it has anything to do with auto-update failure. The original sourcecode touisk mentioned for require_wp_db() is not logical or at least badly coded.

    I really think this should be looked into.

    I seem to get the same error as bimki.
    I have a fresh installation of wp 3.2.1.
    I ran the installer, and it seems okay.
    Then I tried to add a user, and I get that error, on line 318 of the driver.

    Turning on debugging, I see the following: two error messages:

    Error running :
SELECT SQL_CALC_FOUND_ROWS wp_users.ID FROM wp_users WHERE 1=1 ORDER BY user_login ASC LIMIT 20
---- converted to ----
SELECT DISTINCT wp_users."ID" FROM wp_users WHERE 1=1 ORDER BY user_login ASC LIMIT 20
----
ERROR:  for SELECT DISTINCT, ORDER BY expressions must appear in select list
LINE 1: ...CT wp_users."ID" FROM wp_users WHERE 1=1 ORDER BY user_login...
                                                             ^
---------------------
Error running :
SELECT COUNT(NULLIF(<code>meta_value</code> LIKE '%administrator%', FALSE)), COUNT(NULLIF(<code>meta_value</code> LIKE '%editor%', FALSE)), COUNT(NULLIF(<code>meta_value</code> LIKE '%a
uthor%', FALSE)), COUNT(NULLIF(<code>meta_value</code> LIKE '%contributor%', FALSE)), COUNT(NULLIF(<code>meta_value</code> LIKE '%subscriber%', FALSE)), COUNT(*) FROM wp_user
meta WHERE meta_key = 'wp_capabilities'
---- converted to ----
SELECT COUNT(NULLCASE WHEN meta_value ILIKE '%administrator%' THEN  FALSE)) ELSE  COUNT(NULLIF(meta_value ILIKE '%editor%', FALSE END), COUNT(NULLCASE W
HEN meta_value ILIKE '%author%' THEN  FALSE)) ELSE  COUNT(NULLIF(meta_value ILIKE '%contributor%', FALSE END), COUNT(NULLCASE WHEN meta_value ILIKE '%su
bscriber%' THEN  FALSE)) ELSE  COUNT(* END FROM wp_usermeta WHERE meta_key = 'wp_capabilities'
----
ERROR:  syntax error at or near "WHEN"
LINE 1: SELECT COUNT(NULLCASE WHEN meta_value ILIKE '%administrator%...

    For the first error, I am guessing the ORDER BY could be ignored completely… it’s just counting, right?

    I have fixed both of my problems…

    1. I just removed the ‘DISTINCT’ keyword from the substitution. The MySQL version doesn’t have DISTINCT, so I guess this is okay.

    2. The ‘IF’ handling needed to NOT translate if it is a NULLIF, as postgres also supports NULLIF.

    Hi all,
    I am using WordPress 3.2.1
    There seems to be an issue with Pg4Wp plugin. I’ve followed all the instructions. But still I am getting not properly configured website error in the browser.
    Should there be any code changes to be made?
    All the files are in the correct places where they have to be.
    What could be the possible problem?

    I am a beginner (for wordpress and postgreSQL)

    Any help would be appreciated

    Yes, require_wp_db() should be adapted as stated in the first post. Follow it and it should work. In postgres, a database should already be available and a user should have all rights on it.

    Regards,
    Davor

    Thank you.

    Now it says
    “Call to undefined function pg_query() in “wordpress/wp-content/plugins/pg4wp/driver_pgsql.php on line 318”

    You have the pg module in PHP enabled? Search the net. Check also with phpinfo() that your pg_drivers are loaded. Check the php logs, etc.

    I do know that if you follow the installation manuals and pg4wp installation, all should work.

    Thanks davorj. Resolved this.

    Now it gives me 2 warnings, 5 notices and 1 fatal error:
    Warnings: No PostgreSQL link opened yet in driver_pgsql.php in line 318 and 319

    Notices:Constant EZSQL_VERSION,object,OBJECT_K,ARRAY_A,ARRAY_N already defined in wp-includes/wp-db.php

    Fatal Error:Cannot redeclare class wpdb in wp-includes/wp-db.php

    Though the error is similar to the one mentioned in the first post, the solution mentioned is not working.

    Hi,
    I’ve cleared all others except the fatal error.

    I tried changing the functions and caller functions of require_wp_db().
    No change in the error function.

    I am guessing that because the dp.php file(using replace) is replacing the term mysql with pgsql and reading the class “wpdp”. The function require_wp_db() is also declaring the class wpdp. Thus class wpdp is being declared 2 times which is what I think is causing this problem.
    Am I right?
    Is there any way out?
    I am desperately in need for a solution.

    Thanks in advance

Viewing 15 replies - 1 through 15 (of 16 total)
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