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

Attributes

operations  [R]  An array of DDL operations to perform

Public Class methods

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 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 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 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 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 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 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 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 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

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

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

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

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

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

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

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]