Fixing upgrade script failures when a dbprefix is defined in database.php

[abv]

I ran into this issue when attempting to upgrade from version 0.90 to version 1. This commit partially addresses issues where OpenVBX's upgrade scripts cannot run because there is a dbprefix set in database.php.

For example if $db["default"]["dbprefix"] = "vbx_", then the SQL in /updates/47.sql UPDATE settingsSETvalue= '0.91' WHEREname = 'version'... won't execute and the upgrade process will halt and throw an error.

This fix required that $db["default"]["swap_pre"] = "{PRE}" be added to databases.php and the string {PRE} be placed before the names of any tables in any raw SQL executed by CodeIgniter. CodeIgniter's DB driver takes care of the dirty work, and swaps the swap_pre string with the db_prefix string for raw query strings. To see how this works, see line 257 of CodeIgniter's DB_driver.php.

I only added the swap_pre string the updates files 47 and up, because those were the only files that affected our upgrade from version 0.90 to 1.0. I didn't think the scenario where someone upgrading from an earlier version would run into this same issue was realistic. I also looked through OpenVBX's code for other instances where there were raw SQL was being passed to $ci->db->query() but didn't encounter any.

I also, defined the swap_pre string in the database-sample.php -- but obviously, for this to work, the swap_pre string would need to be set to "{PRE}" in database.php.

[Gipetto]

Cool.
I think this is a good change (re: e3c0753). We'll do a evaluation of the OpenVBX code to see how many places this needs to touch.

[abv]

Just noticed that you'd also need to add the {PRE}s to openvbx.sql in the root directory. Sorry about this pull request having multiple commits associated with it. If you run a diff on it, the only differences are the ones related the the dbprefix issue. From now on I'll create a new branch with merged with master, so you don't see any unrelated commits.

[Gipetto]

I've merged this locally and have started testing. I think that the install process should have an advanced option to select the db-prefix as well so I'll be adding that in while I test.

[Gipetto]

There's a fun problem here that may make this hard to do. I've run in to this in the db->query method:

if ( ($this->dbprefix != '' AND $this->swap_pre != '') AND ($this->dbprefix != $this->swap_pre) ) { ... }

That effectively prevents the swap_pre from being processed if there's no dbprefix to swap in, essentially denying us the ability to have optional prefixes. I'm trying to find a way around this without creating too much headache, but I'm not confident that any work around will be without caveats that make creating upgrades harder.

[Gipetto]

I'm gonna shelf this for a later update. I think I want to change to using a prefix by default but need to better plan how to manage the upgrade process.

[Gipetto]

This one is still a touchy subject as CodeIgniter has some very strict handling around the db-prefix. I'm thinking that the correct course of action here would be to start using a db-prefix in new installs of OpenVBX. All in all its a good idea but, as is the case with something like this, it would require lots of testing.

I still want to do this.

[abv]

Thanks for keeping this issue alive. Too bad there isn't an easier way to implement this.

[Gipetto]

Yeah, I was so close and then CodeIgniter slammed the door shut in my face.