abstract public function Schema::changeField in Drupal 8

Same name in this branch

8 core/lib/Drupal/Core/Database/Schema.php \Drupal\Core\Database\Schema::changeField()
8 core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php \Drupal\Core\Database\Driver\sqlite\Schema::changeField()
8 core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php \Drupal\Core\Database\Driver\pgsql\Schema::changeField()
8 core/lib/Drupal/Core/Database/Driver/mysql/Schema.php \Drupal\Core\Database\Driver\mysql\Schema::changeField()

Same name and namespace in other branches

9 core/lib/Drupal/Core/Database/Schema.php \Drupal\Core\Database\Schema::changeField()

Change a field definition.

IMPORTANT NOTE: To maintain database portability, you have to explicitly recreate all indices and primary keys that are using the changed field.

That means that you have to drop all affected keys and indexes with Schema::dropPrimaryKey(), Schema::dropUniqueKey(), or Schema::dropIndex() before calling ::changeField(). To recreate the keys and indices, pass the key definitions as the optional $keys_new argument directly to ::changeField().

For example, suppose you have:

$schema['foo'] = array(
  'fields' => array(
    'bar' => array(
      'type' => 'int',
      'not null' => TRUE,
    ),
  ),
  'primary key' => array(
    'bar',
  ),
);

and you want to change foo.bar to be type serial, leaving it as the primary key. The correct sequence is:

$injected_database
  ->schema()
  ->dropPrimaryKey('foo');
$injected_database
  ->schema()
  ->changeField('foo', 'bar', 'bar', array(
  'type' => 'serial',
  'not null' => TRUE,
), array(
  'primary key' => array(
    'bar',
  ),
));

The reasons for this are due to the different database engines:

On PostgreSQL, changing a field definition involves adding a new field and dropping an old one which* causes any indices, primary keys and sequences (from serial-type fields) that use the changed field to be dropped.

On MySQL, all type 'serial' fields must be part of at least one key or index as soon as they are created. You cannot use Schema::addPrimaryKey, Schema::addUniqueKey(), or Schema::addIndex() for this purpose because the ALTER TABLE command will fail to add the column without a key or index specification. The solution is to use the optional $keys_new argument to create the key or index at the same time as field.

You could use Schema::addPrimaryKey, Schema::addUniqueKey(), or Schema::addIndex() in all cases unless you are converting a field to be type serial. You can use the $keys_new argument in all cases.

Parameters

$table: Name of the table.

$field: Name of the field to change.

$field_new: New name for the field (set to the same as $field if you don't want to change the name).

$spec: The field specification for the new field.

$keys_new: (optional) Keys and indexes specification to be created on the table along with changing the field. The format is the same as a table specification but without the 'fields' element.

Throws

\Drupal\Core\Database\SchemaObjectDoesNotExistException If the specified table or source field doesn't exist.

\Drupal\Core\Database\SchemaObjectExistsException If the specified destination field already exists.

3 methods override Schema::changeField()

Schema::changeField in core/lib/Drupal/Core/Database/Driver/sqlite/Schema.php: Change a field definition.
Schema::changeField in core/lib/Drupal/Core/Database/Driver/pgsql/Schema.php: Change a field definition.
Schema::changeField in core/lib/Drupal/Core/Database/Driver/mysql/Schema.php: Change a field definition.

File

core/lib/Drupal/Core/Database/Schema.php, line 637

Class

Schema: Provides a base implementation for Database Schema.

Namespace

Drupal\Core\Database

Code

public abstract function changeField($table, $field, $field_new, $spec, $keys_new = []);

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