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 249
    249:       def initialize(db, &block)
    250:         @db = db
    251:         @operations = []
    252:         instance_eval(&block) if block
    253:       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 Generator#column for the available options.

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

[Source]

         # File lib/sequel/database/schema_generator.rb, line 259
    259:       def add_column(name, type, opts = {})
    260:         @operations << {:op => :add_column, :name => name, :type => type}.merge(opts)
    261:       end

add_constraint(name, *args, &block)

Add a constraint with the given name and args to the DDL for the table. See Generator#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 268
    268:       def add_constraint(name, *args, &block)
    269:         @operations << {:op => :add_constraint, :name => name, :type => :check, :check => block || args}
    270:       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 Generator#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 exists and will only add 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

[Source]

         # File lib/sequel/database/schema_generator.rb, line 292
    292:       def add_foreign_key(name, table, opts = {})
    293:         return add_composite_foreign_key(name, table, opts) if name.is_a?(Array)
    294:         add_column(name, Integer, {:table=>table}.merge(opts))
    295:       end

add_full_text_index(columns, opts = {})

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

[Source]

         # File lib/sequel/database/schema_generator.rb, line 299
    299:       def add_full_text_index(columns, opts = {})
    300:         add_index(columns, {:type=>:full_text}.merge(opts))
    301:       end

add_index(columns, opts = {})

Add an index on the given columns to the DDL for the table. See Generator#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 307
    307:       def add_index(columns, opts = {})
    308:         @operations << {:op => :add_index, :columns => Array(columns)}.merge(opts)
    309:       end

add_primary_key(name, opts = {})

Add a primary key to the DDL for the table. See Generator#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 317
    317:       def add_primary_key(name, opts = {})
    318:         return add_composite_primary_key(name, opts) if name.is_a?(Array)
    319:         opts = @db.serial_primary_key_options.merge(opts)
    320:         add_column(name, opts.delete(:type), opts)
    321:       end

add_spatial_index(columns, opts = {})

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

[Source]

         # File lib/sequel/database/schema_generator.rb, line 325
    325:       def add_spatial_index(columns, opts = {})
    326:         add_index(columns, {:type=>:spatial}.merge(opts))
    327:       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 276
    276:       def add_unique_constraint(columns, opts = {})
    277:         @operations << {:op => :add_constraint, :type => :unique, :columns => Array(columns)}.merge(opts)
    278:       end

drop_column(name)

Remove a column from the DDL for the table.

      drop_column(:artist_id) # DROP COLUMN artist_id

[Source]

         # File lib/sequel/database/schema_generator.rb, line 332
    332:       def drop_column(name)
    333:         @operations << {:op => :drop_column, :name => name}
    334:       end

drop_constraint(name)

Remove a constraint from the DDL for the table.

      drop_constraint(:unique_name) # DROP CONSTRAINT unique_name

[Source]

         # File lib/sequel/database/schema_generator.rb, line 339
    339:       def drop_constraint(name)
    340:         @operations << {:op => :drop_constraint, :name => name}
    341:       end

drop_index(columns, options={})

Remove an index from the DDL for the table.

      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 348
    348:       def drop_index(columns, options={})
    349:         @operations << {:op => :drop_index, :columns => Array(columns)}.merge(options)
    350:       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 355
    355:       def rename_column(name, new_name, opts = {})
    356:         @operations << {:op => :rename_column, :name => name, :new_name => new_name}.merge(opts)
    357:       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 376
    376:       def set_column_allow_null(name, allow_null)
    377:         @operations << {:op => :set_column_null, :name => name, :null => allow_null}
    378:       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 362
    362:       def set_column_default(name, default)
    363:         @operations << {:op => :set_column_default, :name => name, :default => default}
    364:       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)

[Source]

         # File lib/sequel/database/schema_generator.rb, line 369
    369:       def set_column_type(name, type, opts={})
    370:         @operations << {:op => :set_column_type, :name => name, :type => type}.merge(opts)
    371:       end

[Validate]