マイグレーションクラス¶
Migrations are a convenient way for you to alter your database in a structured and organized manner. You could edit fragments of SQL by hand but you would then be responsible for telling other developers that they need to go and run them. You would also have to keep track of which changes need to be run against the production machines next time you deploy.
The database table migration tracks which migrations have already been run so all you have to do is update your application files and call $this->migration->current() to work out which migrations should be run. The current version is found in application/config/migration.php.
マイグレーションファイル名¶
Each Migration is run in numeric order forward or backwards depending on the method taken. Two numbering styles are available:
- Sequential: each migration is numbered in sequence, starting with 001. Each number must be three digits, and there must not be any gaps in the sequence. (This was the numbering scheme prior to CodeIgniter 3.0.)
- Timestamp: each migration is numbered using the timestamp when the migration was created, in YYYYMMDDHHIISS format (e.g. 20121031100537). This helps prevent numbering conflicts when working in a team environment, and is the preferred scheme in CodeIgniter 3.0 and later.
The desired style may be selected using the $config['migration_type'] setting in your application/config/migration.php file.
Regardless of which numbering style you choose to use, prefix your migration files with the migration number followed by an underscore and a descriptive name for the migration. For example:
- 001_add_blog.php (sequential numbering)
- 20121031100537_add_blog.php (timestamp numbering)
マイグレーションの作成¶
This will be the first migration for a new site which has a blog. All migrations go in the application/migrations/ directory and have names such as 20121031100537_add_blog.php.
<?php
defined('BASEPATH') OR exit('No direct script access allowed');
class Migration_Add_blog extends CI_Migration {
public function up()
{
$this->dbforge->add_field(array(
'blog_id' => array(
'type' => 'INT',
'constraint' => 5,
'unsigned' => TRUE,
'auto_increment' => TRUE
),
'blog_title' => array(
'type' => 'VARCHAR',
'constraint' => '100',
),
'blog_description' => array(
'type' => 'TEXT',
'null' => TRUE,
),
));
$this->dbforge->add_key('blog_id', TRUE);
$this->dbforge->create_table('blog');
}
public function down()
{
$this->dbforge->drop_table('blog');
}
}
Then in application/config/migration.php set $config['migration_version'] = 20121031100537;.
使用例¶
In this example some simple code is placed in application/controllers/Migrate.php to update the schema.:
<?php
class Migrate extends CI_Controller
{
public function index()
{
$this->load->library('migration');
if ($this->migration->current() === FALSE)
{
show_error($this->migration->error_string());
}
}
}
マイグレーション設定¶
The following is a table of all the config options for migrations.
設定項目 | 初期値 | オプション | 説明 |
---|---|---|---|
migration_enabled | FALSE | TRUE / FALSE | Enable or disable migrations. |
migration_path | APPPATH.’migrations/’ | None | The path to your migrations folder. |
migration_version | 0 | None | The current version your database should use. |
migration_table | migrations | None | The table name for storing the schema version number. |
migration_auto_latest | FALSE | TRUE / FALSE | Enable or disable automatically running migrations. |
migration_type | ‘timestamp’ | ‘timestamp’ / ‘sequential’ | The type of numeric identifier used to name migration files. |
クラスリファレンス¶
- class CI_Migration¶
- current()¶
返り値: TRUE if no migrations are found, current version string on success, FALSE on failure 返り値の型: mixed Migrates up to the current version (whatever is set for $config['migration_version'] in application/config/migration.php).
- error_string()¶
返り値: Error messages 返り値の型: string This returns a string of errors that were detected while performing a migration.
- find_migrations()¶
返り値: An array of migration files 返り値の型: array An array of migration filenames are returned that are found in the migration_path property.
- latest()¶
返り値: Current version string on success, FALSE on failure 返り値の型: mixed This works much the same way as current() but instead of looking for the $config['migration_version'] the Migration class will use the very newest migration found in the filesystem.
- version($target_version)¶
パラメータ: - $target_version (mixed) – Migration version to process
返り値: TRUE if no migrations are found, current version string on success, FALSE on failure
返り値の型: mixed
Version can be used to roll back changes or step forwards programmatically to specific versions. It works just like current() but ignores $config['migration_version'].
$this->migration->version(5);