Class | Sequel::Schema::AlterTableGenerator
In: | lib/sequel/database/schema_generator.rb
Parent: | Object

Schema::AlterTableGenerator is an internal class that the user is not expected to instantiate directly. Instances are created by Database#alter_table. It is used to specify table alteration parameters. It takes a Database object and a block of operations to perform on the table, and gives the Database an array of table altering operations, which the database uses to alter a table‘s description.

For more information on Sequel‘s support for schema modification, see the "Migrations and Schema Modification" guide.

### Methods

add_column add_constraint add_foreign_key add_full_text_index add_index add_primary_key add_spatial_index add_unique_constraint drop_column drop_constraint drop_index new rename_column set_column_allow_null set_column_default set_column_type

### Attributes

operations | [R] | An array of DDL operations to perform

### Public Class methods

new(db, &block)

Set the Database object to which to apply the DDL, and evaluate the block in the context of this object.

[Source]

         # File lib/sequel/database/schema_generator.rb, line 280
    280:       def initialize(db, &block)
    281:         @db = db
    282:         @operations = []
    283:         instance_eval(&block) if block
    284:       end

### Public Instance methods

add_column(name, type, opts = {})

Add a column with the given name, type, and opts to the DDL for the table. See CreateTableGenerator#column for the available options.

      add_column(:name, String) # ADD COLUMN name varchar(255)

[Source]

         # File lib/sequel/database/schema_generator.rb, line 290
    290:       def add_column(name, type, opts = {})
    291:         @operations << {:op => :add_column, :name => name, :type => type}.merge(opts)
    292:       end

add_constraint(name, *args, &block)

Add a constraint with the given name and args to the DDL for the table. See CreateTableGenerator#constraint.

      add_constraint(:valid_name, :name.like('A%'))
      # ADD CONSTRAINT valid_name CHECK (name LIKE 'A%')

[Source]

         # File lib/sequel/database/schema_generator.rb, line 299
    299:       def add_constraint(name, *args, &block)
    300:         @operations << {:op => :add_constraint, :name => name, :type => :check, :check => block || args}
    301:       end

add_foreign_key(name, table, opts = {})

Add a foreign key with the given name and referencing the given table to the DDL for the table. See CreateTableGenerator#column for the available options.

You can also pass an array of column names for creating composite foreign keys. In this case, it will assume the columns exist and will only add the constraint. You can provide a :name option to name the constraint.

NOTE: If you need to add a foreign key constraint to a single existing column use the composite key syntax even if it is only one column.

      add_foreign_key(:artist_id, :table) # ADD COLUMN artist_id integer REFERENCES table
      add_foreign_key([:name], :table) # ADD FOREIGN KEY (name) REFERENCES table

PostgreSQL specific options:

:not_valid :

Set to true to add the constraint with the NOT VALID syntax. This makes it so that future inserts must respect referential integrity, but allows the constraint to be added even if existing column values reference rows that do not exist. After all the existing data has been cleaned up, validate_constraint can be used to mark the constraint as valid. Note that this option only makes sense when using an array of columns.

[Source]

         # File lib/sequel/database/schema_generator.rb, line 333
    333:       def add_foreign_key(name, table, opts = {})
    334:         return add_composite_foreign_key(name, table, opts) if name.is_a?(Array)
    335:         add_column(name, Integer, {:table=>table}.merge(opts))
    336:       end

add_full_text_index(columns, opts = {})

Add a full text index on the given columns to the DDL for the table. See CreateTableGenerator#index for available options.

[Source]

         # File lib/sequel/database/schema_generator.rb, line 340
    340:       def add_full_text_index(columns, opts = {})
    341:         add_index(columns, {:type=>:full_text}.merge(opts))
    342:       end

add_index(columns, opts = {})

Add an index on the given columns to the DDL for the table. See CreateTableGenerator#index for available options.

      add_index(:artist_id) # CREATE INDEX table_artist_id_index ON table (artist_id)

[Source]

         # File lib/sequel/database/schema_generator.rb, line 348
    348:       def add_index(columns, opts = {})
    349:         @operations << {:op => :add_index, :columns => Array(columns)}.merge(opts)
    350:       end

add_primary_key(name, opts = {})

Add a primary key to the DDL for the table. See CreateTableGenerator#column for the available options. Like `add_foreign_key`, if you specify the column name as an array, it just creates a constraint:

      add_primary_key(:id) # ADD COLUMN id serial PRIMARY KEY
      add_primary_key([:artist_id, :name]) # ADD PRIMARY KEY (artist_id, name)

[Source]

         # File lib/sequel/database/schema_generator.rb, line 358
    358:       def add_primary_key(name, opts = {})
    359:         return add_composite_primary_key(name, opts) if name.is_a?(Array)
    360:         opts = @db.serial_primary_key_options.merge(opts)
    361:         add_column(name, opts.delete(:type), opts)
    362:       end

add_spatial_index(columns, opts = {})

Add a spatial index on the given columns to the DDL for the table. See CreateTableGenerator#index for available options.

[Source]

         # File lib/sequel/database/schema_generator.rb, line 366
    366:       def add_spatial_index(columns, opts = {})
    367:         add_index(columns, {:type=>:spatial}.merge(opts))
    368:       end

add_unique_constraint(columns, opts = {})

Add a unique constraint to the given column(s)

      add_unique_constraint(:name) # ADD UNIQUE (name)
      add_unique_constraint(:name, :name=>:unique_name) # ADD CONSTRAINT unique_name UNIQUE (name)

[Source]

         # File lib/sequel/database/schema_generator.rb, line 307
    307:       def add_unique_constraint(columns, opts = {})
    308:         @operations << {:op => :add_constraint, :type => :unique, :columns => Array(columns)}.merge(opts)
    309:       end

drop_column(name, opts={})

Remove a column from the DDL for the table.

      drop_column(:artist_id) # DROP COLUMN artist_id
      drop_column(:artist_id, :cascade=>true) # DROP COLUMN artist_id CASCADE

[Source]

         # File lib/sequel/database/schema_generator.rb, line 374
    374:       def drop_column(name, opts={})
    375:         @operations << {:op => :drop_column, :name => name}.merge(opts)
    376:       end

drop_constraint(name, opts={})

Remove a constraint from the DDL for the table. MySQL/SQLite specific options:

:type : | Set the type of constraint to drop, either :primary_key, :foreign_key, or :unique.

      drop_constraint(:unique_name) # DROP CONSTRAINT unique_name
      drop_constraint(:unique_name, :cascade=>true) # DROP CONSTRAINT unique_name CASCADE

[Source]

         # File lib/sequel/database/schema_generator.rb, line 385
    385:       def drop_constraint(name, opts={})
    386:         @operations << {:op => :drop_constraint, :name => name}.merge(opts)
    387:       end

drop_index(columns, options={})

Remove an index from the DDL for the table. General options:

:name : | The name of the index to drop. If not given, uses the same name that would be used by add_index with the same columns.

PostgreSQL specific options:

:cascade : | Cascade the index drop to dependent objects.
:concurrently : | Drop the index using CONCURRENTLY, which doesn‘t block operations on the table. Supported in PostgreSQL 9.2+.
:if_exists : | Only drop the index if it already exists.

      drop_index(:artist_id) # DROP INDEX table_artist_id_index
      drop_index([:a, :b]) # DROP INDEX table_a_b_index
      drop_index([:a, :b], :name=>:foo) # DROP INDEX foo

[Source]

         # File lib/sequel/database/schema_generator.rb, line 404
    404:       def drop_index(columns, options={})
    405:         @operations << {:op => :drop_index, :columns => Array(columns)}.merge(options)
    406:       end

rename_column(name, new_name, opts = {})

Modify a column‘s name in the DDL for the table.

      rename_column(:name, :artist_name) # RENAME COLUMN name TO artist_name

[Source]

         # File lib/sequel/database/schema_generator.rb, line 411
    411:       def rename_column(name, new_name, opts = {})
    412:         @operations << {:op => :rename_column, :name => name, :new_name => new_name}.merge(opts)
    413:       end

set_column_allow_null(name, allow_null)

Modify a column‘s NOT NULL constraint.

      set_column_allow_null(:artist_name, false) # ALTER COLUMN artist_name SET NOT NULL

[Source]

         # File lib/sequel/database/schema_generator.rb, line 436
    436:       def set_column_allow_null(name, allow_null)
    437:         @operations << {:op => :set_column_null, :name => name, :null => allow_null}
    438:       end

set_column_default(name, default)

Modify a column‘s default value in the DDL for the table.

      set_column_default(:artist_name, 'a') # ALTER COLUMN artist_name SET DEFAULT 'a'

[Source]

         # File lib/sequel/database/schema_generator.rb, line 418
    418:       def set_column_default(name, default)
    419:         @operations << {:op => :set_column_default, :name => name, :default => default}
    420:       end

set_column_type(name, type, opts={})

Modify a column‘s type in the DDL for the table.

      set_column_type(:artist_name, 'char(10)') # ALTER COLUMN artist_name TYPE char(10)

PostgreSQL specific options:

:using : | Add a USING clause that specifies how to convert existing values to new values.

[Source]

         # File lib/sequel/database/schema_generator.rb, line 429
    429:       def set_column_type(name, type, opts={})
    430:         @operations << {:op => :set_column_type, :name => name, :type => type}.merge(opts)
    431:       end

[Validate]