ActiveRecord::ConnectionAdapters::SchemaStatements

add_belongs_to(table_name, ref_name, options = {}) Link

Alias for: add_reference

add_column(table_name, column_name, type, options = {}) Link

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

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 372
def add_column(table_name, column_name, type, options = {})
  at = create_alter_table table_name
  at.add_column(column_name, type, options)
  execute schema_creation.accept at
end

add_index(table_name, column_name, options = {}) Link

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.

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, party_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).

Creating a partial index

add_index(:accounts, [:branch_id, :party_id], unique: true, where: "active")

generates:

CREATE UNIQUE INDEX index_accounts_on_branch_id_and_party_id ON accounts(branch_id, party_id) WHERE active

Creating an index with a specific method

add_index(:developers, :name, using: 'btree')

generates:

CREATE INDEX index_developers_on_name ON developers USING btree (name) -- PostgreSQL
CREATE INDEX index_developers_on_name USING btree ON developers (name) -- MySQL

Note: only supported by PostgreSQL and MySQL

Creating an index with a specific type

add_index(:developers, :name, type: :fulltext)

generates:

CREATE FULLTEXT INDEX index_developers_on_name ON developers (name) -- MySQL

Note: only supported by MySQL. Supported: :fulltext and :spatial on MyISAM tables.

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 535
def add_index(table_name, column_name, options = {})
  index_name, index_type, index_columns, index_options = 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})#{index_options}"
end

add_reference(table_name, ref_name, options = {}) Link

Adds a reference. Optionally adds a type column, if :polymorphic option is provided. add_reference and add_belongs_to are acceptable.

Create a user_id column

add_reference(:products, :user)

Create a supplier_id and supplier_type columns

add_belongs_to(:products, :supplier, polymorphic: true)

Create a supplier_id, supplier_type columns and appropriate index

add_reference(:products, :supplier, polymorphic: true, index: true)

Also aliased as: add_belongs_to

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 619
def add_reference(table_name, ref_name, options = {})
  polymorphic = options.delete(:polymorphic)
  index_options = options.delete(:index)
  add_column(table_name, "#{ref_name}_id", :integer, options)
  add_column(table_name, "#{ref_name}_type", :string, polymorphic.is_a?(Hash) ? polymorphic : options) if polymorphic
  add_index(table_name, polymorphic ? %w[id type].map{ |t| "#{ref_name}_#{t}" } : "#{ref_name}_id", index_options.is_a?(Hash) ? index_options : {}) if index_options
end

add_timestamps(table_name) Link

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

add_timestamps(:suppliers)

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 725
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) Link

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 659
def assume_migrated_upto_version(version, migrations_paths = ActiveRecord::Migrator.migrations_paths)
  migrations_paths = Array(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 = {}) Link

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

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

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 406
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) Link

Sets a new default value for a column:

change_column_default(:suppliers, :qualification, 'new')
change_column_default(:accounts, :authorized, 1)

Setting the default to nil effectively drops the default:

change_column_default(:users, :email, nil)

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 419
def change_column_default(table_name, column_name, default)
  raise NotImplementedError, "change_column_default is not implemented"
end

change_column_null(table_name, column_name, null, default = nil) Link

Sets or removes a +NOT NULL+ constraint on a column. The null flag indicates whether the value can be NULL. For example

change_column_null(:users, :nickname, false)

says nicknames cannot be NULL (adds the constraint), whereas

change_column_null(:users, :nickname, true)

allows them to be NULL (drops the constraint).

The method accepts an optional fourth argument to replace existing +NULL+s with some other value. Use that one when enabling the constraint if needed, since otherwise those rows would not be valid.

Please note the fourth argument does not set a column's default.

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 439
def change_column_null(table_name, column_name, null, default = nil)
  raise NotImplementedError, "change_column_null is not implemented"
end

change_table(table_name, options = {}) Link

A block for changing columns in table.

# 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.

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.

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 343
def change_table(table_name, options = {})
  if supports_bulk_alter? && options[:bulk]
    recorder = ActiveRecord::Migration::CommandRecorder.new(self)
    yield update_table_definition(table_name, recorder)
    bulk_change_table(table_name, recorder.commands)
  else
    yield update_table_definition(table_name, self)
  end
end

column_exists?(table_name, column_name, type = nil, options = {}) Link

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

# 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)
column_exists?(:suppliers, :name, :string, default: 'default')
column_exists?(:suppliers, :name, :string, null: false)
column_exists?(:suppliers, :tax, :decimal, precision: 8, scale: 2)

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 73
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.key?(:limit)     || c.limit == options[:limit]) &&
                                (!options.key?(:precision) || c.precision == options[:precision]) &&
                                (!options.key?(:scale)     || c.scale == options[:scale]) &&
                                (!options.key?(:default)   || c.default == options[:default]) &&
                                (!options.key?(:null)      || c.null == options[:null]) }
end

columns(table_name) Link

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

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 57
def columns(table_name) end

create_join_table(table_1, table_2, options = {}) Link

Creates a new join table with the name created using the lexical order of the first two arguments. These arguments can be a String or a Symbol.

# Creates a table called 'assemblies_parts' with no id.
create_join_table(:assemblies, :parts)

You can pass a options hash can include the following keys:

:table_name: Sets the table name overriding the default
:column_options: Any extra options you want appended to the columns 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.

Note that create_join_table does not create any indices by default; you can use its block form to do so yourself:

create_join_table :products, :categories do |t|
  t.index :product_id
  t.index :category_id
end

Add a backend specific option to the generated SQL (MySQL)

create_join_table(:assemblies, :parts, options: 'ENGINE=InnoDB DEFAULT CHARSET=utf8')

generates:

CREATE TABLE assemblies_parts (
  assembly_id int NOT NULL,
  part_id int NOT NULL,
) ENGINE=InnoDB DEFAULT CHARSET=utf8

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 247
def create_join_table(table_1, table_2, options = {})
  join_table_name = find_join_table_name(table_1, table_2, options)

  column_options = options.delete(:column_options) || {}
  column_options.reverse_merge!(null: false)

  t1_column, t2_column = [table_1, table_2].map{ |t| t.to_s.singularize.foreign_key }

  create_table(join_table_name, options.merge!(id: false)) do |td|
    td.integer t1_column, column_options
    td.integer t2_column, column_options
    yield td if block_given?
  end
end

create_table(table_name, options = {}) Link

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.

Note that Active Record models will automatically detect their primary key. This can be avoided by using self.primary_key= on the model to define the key explicitly.

: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.

:as

SQL to use to generate the table. When this option is used, the block is ignored, as are the :id and :primary_key options.

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
)

Create a temporary table based on a query

create_table(:long_query, temporary: true,
  as: "SELECT * FROM orders INNER JOIN line_items ON order_id=orders.id")

generates:

CREATE TEMPORARY TABLE long_query AS
  SELECT * FROM orders INNER JOIN line_items ON order_id=orders.id

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

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 186
def create_table(table_name, options = {})
  td = create_table_definition table_name, options[:temporary], options[:options], options[:as]

  if !options[:as]
    unless options[:id] == false
      pk = options.fetch(:primary_key) {
        Base.get_primary_key table_name.to_s.singularize
      }

      td.primary_key pk, options.fetch(:id, :primary_key), options
    end

    yield td if block_given?
  end

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

  execute schema_creation.accept td
  td.indexes.each_pair { |c,o| add_index table_name, c, o }
end

drop_join_table(table_1, table_2, options = {}) Link

Drops the join table specified by the given arguments. See create_join_table for details.

Although this command ignores the block if one is given, it can be helpful to provide one in a migration's change method so it can be reverted. In that case, the block will be used by create_join_table.

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 268
def drop_join_table(table_1, table_2, options = {})
  join_table_name = find_join_table_name(table_1, table_2, options)
  drop_table(join_table_name)
end

drop_table(table_name, options = {}) Link

Drops a table from the database.

Although this command ignores options and the block if one is given, it can be helpful to provide these in a migration's change method so it can be reverted. In that case, options and the block will be used by create_table.

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 366
def drop_table(table_name, options = {})
  execute "DROP TABLE #{quote_table_name(table_name)}"
end

index_exists?(table_name, column_name, options = {}) Link

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

# 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")

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 45
def index_exists?(table_name, column_name, options = {})
  column_names = Array(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_exists?(table_name, index_name, default) Link

Verifies 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.

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 598
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_table() Link

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

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 655
def initialize_schema_migrations_table
  ActiveRecord::SchemaMigration.create_table
end

native_database_types() Link

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

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 11
def native_database_types
  {}
end

remove_belongs_to(table_name, ref_name, options = {}) Link

Alias for: remove_reference

remove_column(table_name, column_name, type = nil, options = {}) Link

Removes the column from the table definition.

remove_column(:suppliers, :qualification)

The type and options parameters will be ignored if present. It can be helpful to provide these in a migration's change method so it can be reverted. In that case, type and options will be used by add_column.

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 396
def remove_column(table_name, column_name, type = nil, options = {})
  execute "ALTER TABLE #{quote_table_name(table_name)} DROP #{quote_column_name(column_name)}"
end

remove_columns(table_name, *column_names) Link

Removes the given columns from the table definition.

remove_columns(:suppliers, :qualification, :experience)

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 382
def remove_columns(table_name, *column_names)
  raise ArgumentError.new("You must specify at least one column name. Example: remove_columns(:people, :first_name)") if column_names.empty?
  column_names.each do |column_name|
    remove_column(table_name, column_name)
  end
end

remove_index(table_name, options = {}) Link

Removes the given index from the table.

Removes the index_accounts_on_column in the accounts table.

remove_index :accounts, :column

Removes the index named index_accounts_on_branch_id in the accounts table.

remove_index :accounts, column: :branch_id

Removes the index named index_accounts_on_branch_id_and_party_id in the accounts table.

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

Removes the index named by_branch_party in the accounts table.

remove_index :accounts, name: :by_branch_party

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 558
def remove_index(table_name, options = {})
  remove_index!(table_name, index_name_for_remove(table_name, options))
end

remove_reference(table_name, ref_name, options = {}) Link

Removes the reference(s). Also removes a type column if one exists. remove_reference, remove_references and remove_belongs_to are acceptable.

Remove the reference

remove_reference(:products, :user, index: true)

Remove polymorphic reference

remove_reference(:products, :supplier, polymorphic: true)

Also aliased as: remove_belongs_to

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 639
def remove_reference(table_name, ref_name, options = {})
  remove_column(table_name, "#{ref_name}_id")
  remove_column(table_name, "#{ref_name}_type") if options[:polymorphic]
end

remove_timestamps(table_name) Link

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

remove_timestamps(:suppliers)

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 734
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) Link

Renames a column.

rename_column(:suppliers, :description, :name)

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 447
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) Link

Renames 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'

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 572
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
  add_index(table_name, old_index_def.columns, name: new_name, unique: old_index_def.unique)
  remove_index(table_name, name: old_name)
end

rename_table(table_name, new_name) Link

Renames a table.

rename_table('octopuses', 'octopi')

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 357
def rename_table(table_name, new_name)
  raise NotImplementedError, "rename_table is not implemented"
end

table_alias_for(table_name) Link

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

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 16
def table_alias_for(table_name)
  table_name[0...table_alias_length].tr('.', '_')
end

table_exists?(table_name) Link

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

table_exists?(:developers)

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 24
def table_exists?(table_name)
  tables.include?(table_name.to_s)
end

add_index_options(table_name, column_name, options = {}) Link

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 773
def add_index_options(table_name, column_name, options = {})
  column_names = Array(column_name)
  index_name   = index_name(table_name, column: column_names)

  options.assert_valid_keys(:unique, :order, :name, :where, :length, :internal, :using, :algorithm, :type)

  index_type = options[:unique] ? "UNIQUE" : ""
  index_type = options[:type].to_s if options.key?(:type)
  index_name = options[:name].to_s if options.key?(:name)
  max_index_length = options.fetch(:internal, false) ? index_name_length : allowed_index_name_length

  if options.key?(:algorithm)
    algorithm = index_algorithms.fetch(options[:algorithm]) {
      raise ArgumentError.new("Algorithm must be one of the following: #{index_algorithms.keys.map(&:inspect).join(', ')}")
    }
  end

  using = "USING #{options[:using]}" if options[:using].present?

  if supports_partial_index?
    index_options = options[:where] ? " WHERE #{options[:where]}" : ""
  end

  if index_name.length > max_index_length
    raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' is too long; the limit is #{max_index_length} characters"
  end
  if index_name_exists?(table_name, index_name, false)
    raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' already exists"
  end
  index_columns = quoted_columns_for_index(column_names, options).join(", ")

  [index_name, index_type, index_columns, index_options, algorithm, using]
end

add_index_sort_order(option_strings, column_names, options = {}) Link

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 744
def add_index_sort_order(option_strings, column_names, options = {})
  if options.is_a?(Hash) && order = options[:order]
    case order
    when Hash
      column_names.each {|name| option_strings[name] += " #{order[name].upcase}" if order.has_key?(name)}
    when String
      column_names.each {|name| option_strings[name] += " #{order.upcase}"}
    end
  end

  return option_strings
end

index_name_for_remove(table_name, options = {}) Link

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 807
def index_name_for_remove(table_name, options = {})
  index_name = index_name(table_name, options)

  unless index_name_exists?(table_name, index_name, true)
    if options.is_a?(Hash) && options.has_key?(:name)
      options_without_column = options.dup
      options_without_column.delete :column
      index_name_without_column = index_name(table_name, options_without_column)

      return index_name_without_column if index_name_exists?(table_name, index_name_without_column, false)
    end

    raise ArgumentError, "Index name '#{index_name}' on table '#{table_name}' does not exist"
  end

  index_name
end

options_include_default?(options) Link

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 769
def options_include_default?(options)
  options.include?(:default) && !(options[:null] == false && options[:default].nil?)
end

quoted_columns_for_index(column_names, options = {}) Link

Overridden by the mysql adapter for supporting index lengths

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 758
def quoted_columns_for_index(column_names, options = {})
  option_strings = Hash[column_names.map {|name| [name, '']}]

  # add index sort order if supported
  if supports_index_sort_order?
    option_strings = add_index_sort_order(option_strings, column_names, options)
  end

  column_names.map {|name| quote_column_name(name) + option_strings[name]}
end

rename_column_indexes(table_name, column_name, new_column_name) Link

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 834
def rename_column_indexes(table_name, column_name, new_column_name)
  column_name, new_column_name = column_name.to_s, new_column_name.to_s
  indexes(table_name).each do |index|
    next unless index.columns.include?(new_column_name)
    old_columns = index.columns.dup
    old_columns[old_columns.index(new_column_name)] = column_name
    generated_index_name = index_name(table_name, column: old_columns)
    if generated_index_name == index.name
      rename_index table_name, generated_index_name, index_name(table_name, column: index.columns)
    end
  end
end

rename_table_indexes(table_name, new_name) Link

Source: show | on GitHub

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 825
def rename_table_indexes(table_name, new_name)
  indexes(new_name).each do |index|
    generated_index_name = index_name(table_name, column: index.columns)
    if generated_index_name == index.name
      rename_index new_name, generated_index_name, index_name(new_name, column: index.columns)
    end
  end
end

Module ActiveRecord::ConnectionAdapters::SchemaStatements

Creating a simple index

Creating a unique index

Creating a named index

Creating an index with specific key length

Creating an index with a sort order (desc or asc, asc is the default)

Creating a partial index

Creating an index with a specific method

Creating an index with a specific type

Create a user_id column

Create a supplier_id and supplier_type columns

Create a supplier_id, supplier_type columns and appropriate index

Add a column

Add 2 integer columns

Add created_at/updated_at columns

Add a foreign key column

Add a polymorphic foreign key column

Remove a column

Remove several columns

Remove an index

Add a backend specific option to the generated SQL (MySQL)

Block form

Block form, with shorthand

Regular form

Add a backend specific option to the generated SQL (MySQL)

Rename the primary key column

Do not add a primary key column

Create a temporary table based on a query

Remove the reference

Remove polymorphic reference