Module: ActiveRecord::ConnectionAdapters::SchemaStatements

Included in:
AbstractAdapter
Defined in:
activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb

Instance Method Summary collapse

Instance Method Details

#add_column(table_name, column_name, type, options = {}) ⇒ Object

Adds a new column to the named table. See TableDefinition#column for details of the options you can use.


261
262
263
264
265
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 261

def add_column(table_name, column_name, type, options = {})
  add_column_sql = "ALTER TABLE #{quote_table_name(table_name)} ADD #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
  add_column_options!(add_column_sql, options)
  execute(add_column_sql)
end

#add_column_options!(sql, options) ⇒ Object

:nodoc:


499
500
501
502
503
504
505
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 499

def add_column_options!(sql, options) #:nodoc:
  sql << " DEFAULT #{quote(options[:default], options[:column])}" if options_include_default?(options)  # must explicitly check for :null to allow change_column to work on migrations

  if options[:null] == false
    sql << " NOT NULL"
  end
end

#add_index(table_name, column_name, options = {}) ⇒ Object

Adds a new index to the table. column_name can be a single Symbol, or an Array of Symbols.

The index will be named after the table and the column name(s), unless you pass :name as an option.

Examples
Creating a simple index
add_index(:suppliers, :name)

generates

CREATE INDEX suppliers_name_index ON suppliers(name)
Creating a unique index
add_index(:accounts, [:branch_id, :party_id], :unique => true)

generates

CREATE UNIQUE INDEX accounts_branch_id_party_id_index ON accounts(branch_id, party_id)
Creating a named index
add_index(:accounts, [:branch_id, :party_id], :unique => true, :name => 'by_branch_party')

generates

CREATE UNIQUE INDEX by_branch_party ON accounts(branch_id, party_id)
Creating an index with specific key length
add_index(:accounts, :name, :name => 'by_name', :length => 10)

generates

CREATE INDEX by_name ON accounts(name(10))

add_index(:accounts, [:name, :surname], :name => 'by_name_surname', :length => {:name => 10, :surname => 15})

generates

CREATE INDEX by_name_surname ON accounts(name(10), surname(15))

Note: SQLite doesn't support index length

Creating an index with a sort order (desc or asc, asc is the default)
add_index(:accounts, [:branch_id, :party_id, :surname], :order => {:branch_id => :desc, :part_id => :asc})

generates

CREATE INDEX by_branch_desc_party ON accounts(branch_id DESC, party_id ASC, surname)

Note: mysql doesn't yet support index order (it accepts the syntax but ignores it)


350
351
352
353
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 350

def add_index(table_name, column_name, options = {})
  index_name, index_type, index_columns = add_index_options(table_name, column_name, options)
  execute "CREATE #{index_type} INDEX #{quote_column_name(index_name)} ON #{quote_table_name(table_name)} (#{index_columns})"
end

#add_timestamps(table_name) ⇒ Object

Adds timestamps (created_at and updated_at) columns to the named table.

Examples
add_timestamps(:suppliers)

518
519
520
521
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 518

def add_timestamps(table_name)
  add_column table_name, :created_at, :datetime
  add_column table_name, :updated_at, :datetime
end

#assume_migrated_upto_version(version, migrations_paths = ActiveRecord::Migrator.migrations_paths) ⇒ Object


446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 446

def assume_migrated_upto_version(version, migrations_paths = ActiveRecord::Migrator.migrations_paths)
  migrations_paths = Array.wrap(migrations_paths)
  version = version.to_i
  sm_table = quote_table_name(ActiveRecord::Migrator.schema_migrations_table_name)

  migrated = select_values("SELECT version FROM #{sm_table}").map { |v| v.to_i }
  paths = migrations_paths.map {|p| "#{p}/[0-9]*_*.rb" }
  versions = Dir[*paths].map do |filename|
    filename.split('/').last.split('_').first.to_i
  end

  unless migrated.include?(version)
    execute "INSERT INTO #{sm_table} (version) VALUES ('#{version}')"
  end

  inserted = Set.new
  (versions - migrated).each do |v|
    if inserted.include?(v)
      raise "Duplicate migration #{v}. Please renumber your migrations to resolve the conflict."
    elsif v < version
      execute "INSERT INTO #{sm_table} (version) VALUES ('#{v}')"
      inserted << v
    end
  end
end

#change_column(table_name, column_name, type, options = {}) ⇒ Object

Changes the column's definition according to the new options. See TableDefinition#column for details of the options you can use.

Examples
change_column(:suppliers, :name, :string, :limit => 80)
change_column(:accounts, :description, :text)

Raises:

  • (NotImplementedError)

289
290
291
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 289

def change_column(table_name, column_name, type, options = {})
  raise NotImplementedError, "change_column is not implemented"
end

#change_column_default(table_name, column_name, default) ⇒ Object

Sets a new default value for a column.

Examples
change_column_default(:suppliers, :qualification, 'new')
change_column_default(:accounts, :authorized, 1)
change_column_default(:users, :email, nil)

Raises:

  • (NotImplementedError)

298
299
300
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 298

def change_column_default(table_name, column_name, default)
  raise NotImplementedError, "change_column_default is not implemented"
end

#change_table(table_name, options = {}) ⇒ Object

A block for changing columns in table.

Example

# change_table() yields a Table instance
change_table(:suppliers) do |t|
  t.column :name, :string, :limit => 60  # Other column alterations here

end

The options hash can include the following keys:

:bulk

Set this to true to make this a bulk alter query, such as ALTER TABLE `users` ADD COLUMN age INT(11), ADD COLUMN birthdate DATETIME …

Defaults to false.

Examples
Add a column
change_table(:suppliers) do |t|
  t.column :name, :string, :limit => 60
end
Add 2 integer columns
change_table(:suppliers) do |t|
  t.integer :width, :height, :null => false, :default => 0
end
Add created_at/updated_at columns
change_table(:suppliers) do |t|
  t.timestamps
end
Add a foreign key column
change_table(:suppliers) do |t|
  t.references :company
end

Creates a company_id(integer) column

Add a polymorphic foreign key column
change_table(:suppliers) do |t|
  t.belongs_to :company, :polymorphic => true
end

Creates company_type(varchar) and company_id(integer) columns

Remove a column
change_table(:suppliers) do |t|
  t.remove :company
end
Remove several columns
change_table(:suppliers) do |t|
  t.remove :company_id
  t.remove :width, :height
end
Remove an index
change_table(:suppliers) do |t|
  t.remove_index :company_id
end

See also Table for details on all of the various column transformation


237
238
239
240
241
242
243
244
245
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 237

def change_table(table_name, options = {})
  if supports_bulk_alter? && options[:bulk]
    recorder = ActiveRecord::Migration::CommandRecorder.new(self)
    yield Table.new(table_name, recorder)
    bulk_change_table(table_name, recorder.commands)
  else
    yield Table.new(table_name, self)
  end
end

#column_exists?(table_name, column_name, type = nil, options = {}) ⇒ Boolean

Checks to see if a column exists in a given table.

Examples

# Check a column exists
column_exists?(:suppliers, :name)

# Check a column exists of a particular type
column_exists?(:suppliers, :name, :string)

# Check a column exists with a specific definition
column_exists?(:suppliers, :name, :string, :limit => 100)

Returns:

  • (Boolean)

69
70
71
72
73
74
75
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 69

def column_exists?(table_name, column_name, type = nil, options = {})
  columns(table_name).any?{ |c| c.name == column_name.to_s &&
                                (!type                 || c.type == type) &&
                                (!options[:limit]      || c.limit == options[:limit]) &&
                                (!options[:precision]  || c.precision == options[:precision]) &&
                                (!options[:scale]      || c.scale == options[:scale]) }
end

#columns(table_name, name = nil) ⇒ Object

Returns an array of Column objects for the table specified by table_name. See the concrete implementation for details on the expected parameter values.


56
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 56

def columns(table_name, name = nil) end

#create_table(table_name, options = {}) {|td| ... } ⇒ Object

Creates a new table with the name table_name. table_name may either be a String or a Symbol.

There are two ways to work with create_table. You can use the block form or the regular form, like this:

Block form

# create_table() passes a TableDefinition object to the block.
# This form will not only create the table, but also columns for the
# table.

create_table(:suppliers) do |t|
  t.column :name, :string, :limit => 60  # Other fields here

end

Block form, with shorthand

# You can also use the column types as method calls, rather than calling the column method.
create_table(:suppliers) do |t|
  t.string :name, :limit => 60  # Other fields here

end

Regular form

# Creates a table called 'suppliers' with no columns.
create_table(:suppliers)# Add a column to 'suppliers'.

add_column(:suppliers, :name, :string, {:limit => 60})

The options hash can include the following keys:

:id

Whether to automatically add a primary key column. Defaults to true. Join tables for has_and_belongs_to_many should set it to false.

:primary_key

The name of the primary key, if one is to be added automatically. Defaults to id. If :id is false this option is ignored.

Also note that this just sets the primary key in the table. You additionally need to configure the primary key in the model via self.primary_key=. Models do NOT auto-detect the primary key from their table definition.

:options

Any extra options you want appended to the table definition.

:temporary

Make a temporary table.

:force

Set to true to drop the table before creating it. Defaults to false.

Examples
Add a backend specific option to the generated SQL (MySQL)
create_table(:suppliers, :options => 'ENGINE=InnoDB DEFAULT CHARSET=utf8')

generates:

CREATE TABLE suppliers (
  id int(11) DEFAULT NULL auto_increment PRIMARY KEY
) ENGINE=InnoDB DEFAULT CHARSET=utf8
Rename the primary key column
create_table(:objects, :primary_key => 'guid') do |t|
  t.column :name, :string, :limit => 80
end

generates:

CREATE TABLE objects (
  guid int(11) DEFAULT NULL auto_increment PRIMARY KEY,
  name varchar(80)
)
Do not add a primary key column
create_table(:categories_suppliers, :id => false) do |t|
  t.column :category_id, :integer
  t.column :supplier_id, :integer
end

generates:

CREATE TABLE categories_suppliers (
  category_id int,
  supplier_id int
)

See also TableDefinition#column for details on how to create columns.

Yields:

  • (td)

156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 156

def create_table(table_name, options = {})
  td = table_definition
  td.primary_key(options[:primary_key] || Base.get_primary_key(table_name.to_s.singularize)) unless options[:id] == false

  yield td if block_given?

  if options[:force] && table_exists?(table_name)
    drop_table(table_name, options)
  end

  create_sql = "CREATE#{' TEMPORARY' if options[:temporary]} TABLE "
  create_sql << "#{quote_table_name(table_name)} ("
  create_sql << td.to_sql
  create_sql << ") #{options[:options]}"
  execute create_sql
end

#distinct(columns, order_by) ⇒ Object

SELECT DISTINCT clause for a given set of columns and a given ORDER BY clause. Both PostgreSQL and Oracle overrides this for custom DISTINCT syntax.

distinct("posts.id", "posts.created_at desc")

511
512
513
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 511

def distinct(columns, order_by)
  "DISTINCT #{columns}"
end

#drop_table(table_name, options = {}) ⇒ Object

Drops a table from the database.


255
256
257
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 255

def drop_table(table_name, options = {})
  execute "DROP TABLE #{quote_table_name(table_name)}"
end

#dump_schema_informationObject

:nodoc:


414
415
416
417
418
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 414

def dump_schema_information #:nodoc:
  sm_table = ActiveRecord::Migrator.schema_migrations_table_name
  migrated = select_values("SELECT version FROM #{sm_table} ORDER BY version")
  migrated.map { |v| "INSERT INTO #{sm_table} (version) VALUES ('#{v}');" }.join("\n\n")
end

#index_exists?(table_name, column_name, options = {}) ⇒ Boolean

Checks to see if an index exists on a table for a given index definition.

Examples

# Check an index exists
index_exists?(:suppliers, :company_id)

# Check an index on multiple columns exists
index_exists?(:suppliers, [:company_id, :company_type])

# Check a unique index exists
index_exists?(:suppliers, :company_id, :unique => true)

# Check an index with a custom name exists
index_exists?(:suppliers, :company_id, :name => "idx_company_id"

Returns:

  • (Boolean)

44
45
46
47
48
49
50
51
52
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 44

def index_exists?(table_name, column_name, options = {})
  column_names = Array.wrap(column_name)
  index_name = options.key?(:name) ? options[:name].to_s : index_name(table_name, :column => column_names)
  if options[:unique]
    indexes(table_name).any?{ |i| i.unique && i.name == index_name }
  else
    indexes(table_name).any?{ |i| i.name == index_name }
  end
end

#index_name(table_name, options) ⇒ Object

:nodoc:


385
386
387
388
389
390
391
392
393
394
395
396
397
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 385

def index_name(table_name, options) #:nodoc:
  if Hash === options # legacy support
    if options[:column]
      "index_#{table_name}_on_#{Array.wrap(options[:column]) * '_and_'}"
    elsif options[:name]
      options[:name]
    else
      raise ArgumentError, "You must specify the index name"
    end
  else
    index_name(table_name, :column => options)
  end
end

#index_name_exists?(table_name, index_name, default) ⇒ Boolean

Verify the existence of an index with a given name.

The default argument is returned if the underlying implementation does not define the indexes method, as there's no way to determine the correct answer in that case.

Returns:

  • (Boolean)

403
404
405
406
407
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 403

def index_name_exists?(table_name, index_name, default)
  return default unless respond_to?(:indexes)
  index_name = index_name.to_s
  indexes(table_name).detect { |i| i.name == index_name }
end

#initialize_schema_migrations_tableObject

Should not be called normally, but this operation is non-destructive. The migrations module handles this automatically.


422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 422

def initialize_schema_migrations_table
  sm_table = ActiveRecord::Migrator.schema_migrations_table_name

  unless table_exists?(sm_table)
    create_table(sm_table, :id => false) do |schema_migrations_table|
      schema_migrations_table.column :version, :string, :null => false
    end
    add_index sm_table, :version, :unique => true,
      :name => "#{Base.table_name_prefix}unique_schema_migrations#{Base.table_name_suffix}"

    # Backwards-compatibility: if we find schema_info, assume we've
    # migrated up to that point:
    si_table = Base.table_name_prefix + 'schema_info' + Base.table_name_suffix

    if table_exists?(si_table)
      ActiveSupport::Deprecation.warn "Usage of the schema table `#{si_table}` is deprecated. Please switch to using `schema_migrations` table"

      old_version = select_value("SELECT version FROM #{quote_table_name(si_table)}").to_i
      assume_migrated_upto_version(old_version)
      drop_table(si_table)
    end
  end
end

#native_database_typesObject

Returns a Hash of mappings from the abstract data types to the native database types. See TableDefinition#column for details on the recognized abstract data types.


10
11
12
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 10

def native_database_types
  {}
end

#remove_column(table_name, *column_names) ⇒ Object Also known as: remove_columns

Removes the column(s) from the table definition.

Examples
remove_column(:suppliers, :qualification)
remove_columns(:suppliers, :qualification, :experience)

271
272
273
274
275
276
277
278
279
280
281
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 271

def remove_column(table_name, *column_names)
  if column_names.flatten!
    message = 'Passing array to remove_columns is deprecated, please use ' +
              'multiple arguments, like: `remove_columns(:posts, :foo, :bar)`'
    ActiveSupport::Deprecation.warn message, caller
  end

  columns_for_remove(table_name, *column_names).each do |column_name|
    execute "ALTER TABLE #{quote_table_name(table_name)} DROP #{column_name}"
  end
end

#remove_index(table_name, options = {}) ⇒ Object

Remove the given index from the table.

Remove the index_accounts_on_column in the accounts table.

remove_index :accounts, :column

Remove the index named index_accounts_on_branch_id in the accounts table.

remove_index :accounts, :column => :branch_id

Remove the index named index_accounts_on_branch_id_and_party_id in the accounts table.

remove_index :accounts, :column => [:branch_id, :party_id]

Remove the index named by_branch_party in the accounts table.

remove_index :accounts, :name => :by_branch_party

365
366
367
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 365

def remove_index(table_name, options = {})
  remove_index!(table_name, index_name_for_remove(table_name, options))
end

#remove_index!(table_name, index_name) ⇒ Object

:nodoc:


369
370
371
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 369

def remove_index!(table_name, index_name) #:nodoc:
  execute "DROP INDEX #{quote_column_name(index_name)} ON #{quote_table_name(table_name)}"
end

#remove_timestamps(table_name) ⇒ Object

Removes the timestamp columns (created_at and updated_at) from the table definition.

Examples
remove_timestamps(:suppliers)

526
527
528
529
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 526

def remove_timestamps(table_name)
  remove_column table_name, :updated_at
  remove_column table_name, :created_at
end

#rename_column(table_name, column_name, new_column_name) ⇒ Object

Renames a column.

Example
rename_column(:suppliers, :description, :name)

Raises:

  • (NotImplementedError)

305
306
307
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 305

def rename_column(table_name, column_name, new_column_name)
  raise NotImplementedError, "rename_column is not implemented"
end

#rename_index(table_name, old_name, new_name) ⇒ Object

Rename an index.

Rename the index_people_on_last_name index to index_users_on_last_name

rename_index :people, 'index_people_on_last_name', 'index_users_on_last_name'

377
378
379
380
381
382
383
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 377

def rename_index(table_name, old_name, new_name)
  # this is a naive implementation; some DBs may support this more efficiently (Postgres, for instance)
  old_index_def = indexes(table_name).detect { |i| i.name == old_name }
  return unless old_index_def
  remove_index(table_name, :name => old_name)
  add_index(table_name, old_index_def.columns, :name => new_name, :unique => old_index_def.unique)
end

#rename_table(table_name, new_name) ⇒ Object

Renames a table.

Example
rename_table('octopuses', 'octopi')

Raises:

  • (NotImplementedError)

250
251
252
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 250

def rename_table(table_name, new_name)
  raise NotImplementedError, "rename_table is not implemented"
end

#structure_dumpObject

Returns a string of CREATE TABLE SQL statement(s) for recreating the entire structure of the database.


411
412
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 411

def structure_dump
end

#table_alias_for(table_name) ⇒ Object

Truncates a table alias according to the limits of the current adapter.


15
16
17
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 15

def table_alias_for(table_name)
  table_name[0...table_alias_length].gsub(/\./, '_')
end

#table_exists?(table_name) ⇒ Boolean

Checks to see if the table table_name exists on the database.

Example

table_exists?(:developers)

Returns:

  • (Boolean)

23
24
25
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 23

def table_exists?(table_name)
  tables.include?(table_name.to_s)
end

#type_to_sql(type, limit = nil, precision = nil, scale = nil) ⇒ Object

:nodoc:


472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 472

def type_to_sql(type, limit = nil, precision = nil, scale = nil) #:nodoc:
  if native = native_database_types[type.to_sym]
    column_type_sql = (native.is_a?(Hash) ? native[:name] : native).dup

    if type == :decimal # ignore limit, use precision and scale
      scale ||= native[:scale]

      if precision ||= native[:precision]
        if scale
          column_type_sql << "(#{precision},#{scale})"
        else
          column_type_sql << "(#{precision})"
        end
      elsif scale
        raise ArgumentError, "Error adding decimal column: precision cannot be empty if scale if specified"
      end

    elsif (type != :primary_key) && (limit ||= native.is_a?(Hash) && native[:limit])
      column_type_sql << "(#{limit})"
    end

    column_type_sql
  else
    type
  end
end