Module: ActiveRecord::ConnectionAdapters::SchemaStatements

Includes:
Migration::JoinTable
Included in:
AbstractAdapter
Defined in:
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.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 357

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_column_options!(sql, options) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 697

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
  if options[:auto_increment] == true
    sql << " AUTO_INCREMENT"
  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.

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.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 520

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 = {}) ⇒ Object Also known as: add_belongs_to

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)



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 604

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 : nil) if index_options
end

#add_timestamps(table_name) ⇒ Object

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

add_timestamps(:suppliers)



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 730

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 



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 644

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 = {}) ⇒ Object

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

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

Raises:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 391

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:

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)

Raises:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 404

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) ⇒ Object

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.

Raises:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 424

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 = {}) ⇒ Object

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.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 328

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 = {}) ⇒ Boolean

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)

Returns:



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# File '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) ⇒ 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.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 57

def columns(table_name) end

#columns_for_distinct(columns, orders) ⇒ Object

Given a set of columns and an ORDER BY clause, returns the columns for a SELECT DISTINCT. Both PostgreSQL and Oracle overrides this for custom DISTINCT syntax - they require the order columns appear in the SELECT.

columns_for_distinct("posts.id", ["posts.created_at desc"])



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 722

def columns_for_distinct(columns, orders) #:nodoc:
  columns
end

#create_join_table(table_1, table_2, options = {}) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 232

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 = {}) {|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.

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.

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) 


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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 173

def create_table(table_name, options = {})
  td = create_table_definition table_name, options[:temporary], options[:options]

  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?

  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

#distinct(columns, order_by) ⇒ Object

SELECT DISTINCT clause for a given set of columns and a given ORDER BY clause.

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



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 712

def distinct(columns, order_by)
  ActiveSupport::Deprecation.warn("#distinct is deprecated and shall be removed from future releases.")
  "DISTINCT #{columns_for_distinct(columns, order_by)}"
end

#drop_join_table(table_1, table_2, options = {}) ⇒ Object

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.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 253

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 = {}) ⇒ Object

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.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 351

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

#dump_schema_information ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 630

def dump_schema_information #:nodoc:
  sm_table = ActiveRecord::Migrator.schema_migrations_table_name

  ActiveRecord::SchemaMigration.order('version').map { |sm|
    "INSERT INTO #{sm_table} (version) VALUES ('#{sm.version}');"
  }.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.

# 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:



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# File '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(table_name, options) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 565

def index_name(table_name, options) #:nodoc:
  if Hash === options
    if options[:column]
      "index_#{table_name}_on_#{Array(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

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.

Returns:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 583

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 ⇒ Object

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



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 640

def initialize_schema_migrations_table
  ActiveRecord::SchemaMigration.create_table
end

#native_database_types ⇒ Object

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.



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

def native_database_types
  {}
end

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

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.



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 381

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) ⇒ Object

Removes the given columns from the table definition.

remove_columns(:suppliers, :qualification, :experience)

Raises:



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

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 = {}) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 543

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:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 547

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

#remove_reference(table_name, ref_name, options = {}) ⇒ Object Also known as: remove_belongs_to

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)



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 624

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) ⇒ Object

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

remove_timestamps(:suppliers)



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 739

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.

rename_column(:suppliers, :description, :name)

Raises:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 432

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

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'



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 557

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.

rename_table('octopuses', 'octopi')

Raises:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 342

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

#table_alias_for(table_name) ⇒ Object

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



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# File '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) ⇒ Boolean

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

table_exists?(:developers)

Returns:



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

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

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

:nodoc:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 670

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 is specified"
      end

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

    column_type_sql
  else
    type.to_s
  end
end

#update_table_definition(table_name, base) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/abstract/schema_statements.rb', line 744

def update_table_definition(table_name, base) #:nodoc:
  Table.new(table_name, base)
end