Module: ActiveRecord::ConnectionAdapters::SchemaStatements

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

Instance Method Summary (collapse)

Instance Method Details

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

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



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 262

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

- (Object) add_column_options!(sql, options)

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 490

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

- (Object) add_index(table_name, column_name, options = {})

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 first column name, unless you pass :name as an option.

When creating an index on multiple columns, the first column is used as a name for the index. For example, when you specify an index on two columns [:first, :last], the DBMS creates an index for both columns as well as an index for the first column :first. Using just the first name for this index makes sense, because you will never have to create a singular index with this name.

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



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

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

- (Object) add_timestamps(table_name)

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

Examples
add_timestamps(:suppliers)


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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 509

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

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



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 437

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

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

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)


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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 282

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

- (Object) change_column_default(table_name, column_name, default)

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)


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

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

- (Object) change_table(table_name, options = {})

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



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 238

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

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

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)


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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 70

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

- (Object) columns(table_name, name = nil)

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

def columns(table_name, name = nil) end

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

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 the set_primary_key macro. 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)


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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 157

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

- (Object) distinct(columns, order_by)

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")


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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 502

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

- (Object) drop_table(table_name, options = {})

Drops a table from the database.



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

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

- (Object) dump_schema_information

:nodoc:



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

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

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

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)


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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 45

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

- (Object) index_name(table_name, options)

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 377

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

- (Boolean) index_name_exists?(table_name, index_name, default)

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)


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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 395

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

- (Object) initialize_schema_migrations_table

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



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 414

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)

      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

- (Object) native_database_types

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 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 9

def native_database_types
  {}
end

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

Removes the column(s) from the table definition.

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


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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 272

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

- (Object) remove_index(table_name, options = {})

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


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

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

- (Object) remove_index!(table_name, index_name)

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 361

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

- (Object) remove_timestamps(table_name)

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

Examples
remove_timestamps(:suppliers)


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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 517

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

- (Object) rename_column(table_name, column_name, new_column_name)

Renames a column.

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

Raises:

  • (NotImplementedError)


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

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

- (Object) rename_index(table_name, old_name, new_name)

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'


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

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

- (Object) rename_table(table_name, new_name)

Renames a table.

Example
rename_table('octopuses', 'octopi')

Raises:

  • (NotImplementedError)


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

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

- (Object) structure_dump

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



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 403

def structure_dump
end

- (Object) table_alias_for(table_name)

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



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 14

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

- (Boolean) table_exists?(table_name)

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

Example

table_exists?(:developers)

Returns:

  • (Boolean)


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# 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

- (Object) type_to_sql(type, limit = nil, precision = nil, scale = nil)

:nodoc:



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# File 'activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb', line 463

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