[commits] [Wiki] created: UpdatingYourDatabaseSchema

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guest [80.153.12.208]  Thu, 18 Dec 2014 09:59:10 +0000

Created page: http://wiki.horde.org/UpdatingYourDatabaseSchema

[[toc]]

+ Migration Mechanism

When you take your application to a new revision, you may whish to  
change your SQL database schema. Tables may be added or removed and  
columns in a table may be added or removed. For this, horde provides  
the migration mechanism.
+ Files

Files under
<code type="shell">
<appname>/migration/
</code>

control the migration process. File naming follows the pattern

<code type="shell">
<n>_<appname>_[base|upgrade]_<name>.php
</code>

It appears that the [base|upgrade] part in the file name is not  
relevant and just supposed to indicate whether something is created or  
modified. Still, the horde applications all seem to make use of it.

Inside the file there is a class defined which must be called
<code type="shell">
<Appname>[Base|Upgrade]<Name>
</code>

Note that the file name is all lowercase and the class name is  
CamelCase. The class may define an "up" for upgrading an installation  
and a "down" method for removing the installation, for instance if you  
which to remove your application from the horde system. For  
implementation of the methods feel free to steal code from one of the  
existing horde applications.
Usage

When you use the admin console, horde determines if the revision  
number of your application matches the highest number of migration  
files found. If not, the console notifies you ("DB schema needs  
update") and lets you trigger the migration process with the click of  
a button. All migration files with numbers between the current  
revision and the highest number found in a file name will the be  
considered and the up-methods of those files will be called. The  
revision number of your application will be set accordingly. Note that  
this revision number will not necessarily match the version number  
defined in

<code type="shell">
<application>/lib/Application.php
</code>

Alternatively, you may run the CLI script horde-db-migrate, which  
should already be in your shell search path. The CLI is especially  
useful for re-running a migration script as horde will not notice a  
change in one of the migration files. It also acdcepts a revision  
number to set.