Sequel::Schema::AlterTableGenerator

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

Public Class

new

Public Instance

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
operations
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.

# File lib/sequel/database/schema_generator.rb, line 257
def initialize(db, &block)
  @db = db
  @operations = []
  instance_eval(&block) if block
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)

# File lib/sequel/database/schema_generator.rb, line 267
def add_column(name, type, opts = {})
  @operations << {:op => :add_column, :name => name, :type => type}.merge(opts)
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%')

# File lib/sequel/database/schema_generator.rb, line 276
def add_constraint(name, *args, &block)
  @operations << {:op => :add_constraint, :name => name, :type => :check, :check => block || args}
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 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

# File lib/sequel/database/schema_generator.rb, line 300
def add_foreign_key(name, table, opts = {})
  return add_composite_foreign_key(name, table, opts) if name.is_a?(Array)
  add_column(name, Integer, {:table=>table}.merge(opts))
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.

# File lib/sequel/database/schema_generator.rb, line 307
def add_full_text_index(columns, opts = {})
  add_index(columns, {:type=>:full_text}.merge(opts))
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)

# File lib/sequel/database/schema_generator.rb, line 315
def add_index(columns, opts = {})
  @operations << {:op => :add_index, :columns => Array(columns)}.merge(opts)
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)

# File lib/sequel/database/schema_generator.rb, line 325
def add_primary_key(name, opts = {})
  return add_composite_primary_key(name, opts) if name.is_a?(Array)
  opts = @db.serial_primary_key_options.merge(opts)
  add_column(name, opts.delete(:type), opts)
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.

# File lib/sequel/database/schema_generator.rb, line 333
def add_spatial_index(columns, opts = {})
  add_index(columns, {:type=>:spatial}.merge(opts))
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)

# File lib/sequel/database/schema_generator.rb, line 284
def add_unique_constraint(columns, opts = {})
  @operations << {:op => :add_constraint, :type => :unique, :columns => Array(columns)}.merge(opts)
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

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

drop_constraint (name, opts={})

Remove a constraint from the DDL for the table.

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

# File lib/sequel/database/schema_generator.rb, line 349
def drop_constraint(name, opts={})
  @operations << {:op => :drop_constraint, :name => name}.merge(opts)
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

# File lib/sequel/database/schema_generator.rb, line 358
def drop_index(columns, options={})
  @operations << {:op => :drop_index, :columns => Array(columns)}.merge(options)
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

# File lib/sequel/database/schema_generator.rb, line 365
def rename_column(name, new_name, opts = {})
  @operations << {:op => :rename_column, :name => name, :new_name => new_name}.merge(opts)
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

# File lib/sequel/database/schema_generator.rb, line 386
def set_column_allow_null(name, allow_null)
  @operations << {:op => :set_column_null, :name => name, :null => allow_null}
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'

# File lib/sequel/database/schema_generator.rb, line 372
def set_column_default(name, default)
  @operations << {:op => :set_column_default, :name => name, :default => default}
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)

# File lib/sequel/database/schema_generator.rb, line 379
def set_column_type(name, type, opts={})
  @operations << {:op => :set_column_type, :name => name, :type => type}.merge(opts)
end