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Fixes #4800.

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This commit is contained in:
Qiang Xue
2014-08-23 18:18:31 -04:00
parent 5a87ebadd4
commit 385e13978d
2 changed files with 42 additions and 17 deletions
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48
docs/guide/db-migrations.md
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@ -338,26 +338,44 @@ Now if we run the `migrate` command, the above configurations will take effect
without requiring us to enter the command line options every time. Other command options
can be also configured this way.
### Managing migrations for multiple databases
The preferred way to manage migrations for multiple databases is to create a directory for each database's migrations, and then run the migrate command for each database like this:
### Migrating with Multiple Databases
By default, migrations will be applied to the database specified by the `db` application component.
You may change it by specifying the `--db` option, for example,
```
yii migrate --migrationPath=@app/migrations/db2 --db=db2
yii migrate --db=db2
```
```
yii migrate create <name> --migrationPath=@app/migrations/db2 --db=db2
```
This way you have full control on which database corresponds to which migration directory. Another benefit is that migration history is kept in the database migrations are applied to. So each database would keep it's migration history.
The above command will apply *all* migrations found in the default migration path to the `db2` database.
If your application works with multiple databases, some migrations should be applied to one database while
some others should be applied to another database. In this case, it is recommended that you create a base
migration class for each different database and override the [[yii\db\Migration::init()]] method like the following,
Alternative approach is set the database, which the migration should be performed on, in the migration class. To do so, we need to override the [[yii\db\Migration::init()]] method as follows:
```php
public function init()
{
parent::init();
$this->db = Yii::$app->dbConnectionId;
}
public function init()
{
$this->db = 'db2';
parent::init();
}
```
If a migration needs to be applied to one database, you create a migration class by extending from the corresponding
base migration class.
Now if you run the `yii migrate` command, each migration will be applied to the corresponding database.
Because each migration has harcoded the DB connection, the `--db` option of the `migrate` command will have no effect.
If you still want to support changing DB connection via the `--db` option, you may take the following alternative
approach to work with multiple databases.
For each database, create a migration path and save all corresponding migration classes there. To apply migrations,
run the command as follows,
```
where `dbConnectionId` is ID of the database application component. This approach is much faster to implement and use, you create and apply migrations running migrate command as usual, without providing extra parameters. We recommend using [[yii\db\Migration::init()]] with caution though, as in this case the migration history is saved to the database configured in [[yii\console\controllers\MigrateController::db]]
- database which MigrateController currently operates on.
yii migrate --migrationPath=@app/migrations/db1 --db=db1
yii migrate --migrationPath=@app/migrations/db2 --db=db2
...
```