Module: ActiveRecord::ConnectionAdapters::DatabaseStatements

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Included In: `AbstractAdapter`, `AbstractMysqlAdapter`, `Mysql2Adapter`, `PostgreSQLAdapter`, `SQLite3Adapter`, `TrilogyAdapter`
Defined in:	activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb

Constant Summary

DEFAULT_INSERT_VALUE = private
# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 551
```
Arel.sql("DEFAULT").freeze
```
HIGH_PRECISION_CURRENT_TIMESTAMP = private Internal use only

This is a safe default, even if not high precision on all databases

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 515
```
Arel.sql("CURRENT_TIMESTAMP", retryable: true).freeze
```

Instance Attribute Summary

#begin_transaction readonly
#commit_transaction readonly
#current_transaction readonly
#dirty_current_transaction readonly
#materialize_transactions readonly
#open_transactions readonly
#rollback_transaction readonly
#transaction_open? ⇒ Boolean readonly
#within_new_transaction readonly
#transaction_manager readonly Internal use only

Instance Method Summary

#add_transaction_record(record, ensure_finalize = true)

Register a record with the current transaction so that its after_commit and after_rollback callbacks can be called.
#begin_db_transaction

Begins the transaction (and turns off auto-committing).
#begin_isolated_db_transaction(isolation)

Begins the transaction with the isolation level set.
#commit_db_transaction

Commits the transaction (and turns on auto-committing).
#create(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = [], returning: nil)

Alias for #insert.
#default_sequence_name(table, column)
#delete(arel, name = nil, binds = [])

Executes the delete statement and returns the number of rows affected.
#disable_lazy_transactions!
#empty_insert_statement_value(primary_key = nil)
#enable_lazy_transactions!
#exec_delete(sql, name = nil, binds = [])

Executes delete sql statement in the context of this connection using binds as the bind substitutes.
#exec_insert(sql, name = nil, binds = [], pk = nil, sequence_name = nil, returning: nil)

Executes insert sql statement in the context of this connection using binds as the bind substitutes.
#exec_query(sql, name = "SQL", binds = [], prepare: false)

Executes sql statement in the context of this connection using binds as the bind substitutes.
#exec_update(sql, name = nil, binds = [])

Executes update sql statement in the context of this connection using binds as the bind substitutes.
#execute(sql, name = nil, allow_retry: false)

Executes the SQL statement in the context of this connection and returns the raw result from the connection adapter.
#high_precision_current_timestamp

Returns an ::Arel SQL literal for the CURRENT_TIMESTAMP for usage with arbitrary precision date/time columns.
#initialize
#insert(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = [], returning: nil) (also: #create)

Executes an INSERT query and returns the new record’s ID.
#insert_fixture(fixture, table_name)

Inserts the given fixture into the table.
#insert_fixtures_set(fixture_set, tables_to_delete = [])
#reset_sequence!(table, column, sequence = nil)

Set the sequence to the max value of the table’s column.
#restart_db_transaction
#rollback_db_transaction

Rolls back the transaction (and turns on auto-committing).
#rollback_to_savepoint(name = nil)
#sanitize_limit(limit)

Sanitizes the given LIMIT parameter in order to prevent SQL injection.
#select_all(arel, name = nil, binds = [], preparable: nil, async: false, allow_retry: false)

Returns an ::ActiveRecord::Result instance.
#select_one(arel, name = nil, binds = [], async: false)

Returns a record hash with the column names as keys and column values as values.
#select_rows(arel, name = nil, binds = [], async: false)

Returns an array of arrays containing the field values.
#select_value(arel, name = nil, binds = [], async: false)

Returns a single value from a record.
#select_values(arel, name = nil, binds = [])

Returns an array of the values of the first column in a select:
#to_sql(arel_or_sql_string, binds = [])

Converts an arel AST to SQL.
#transaction(requires_new: nil, isolation: nil, joinable: true, &block)

Runs the given block in a database transaction, and returns the result of the block.
#transaction_isolation_levels
#truncate(table_name, name = nil)

Executes the truncate statement.
#update(arel, name = nil, binds = [])

Executes the update statement and returns the number of rows affected.
#write_query?(sql) ⇒ Boolean

Determines whether the SQL statement is a write query.
#arel_from_relation(relation) private
#build_fixture_sql(fixtures, table_name) private
#build_fixture_statements(fixture_set) private
#build_truncate_statement(table_name) private
#build_truncate_statements(table_names) private
#combine_multi_statements(total_sql) private
#default_insert_value(column) private
#execute_batch(statements, name = nil) private
#extract_table_ref_from_insert_sql(sql) private
#internal_execute(sql, name = "SCHEMA", allow_retry: false, materialize_transactions: true) private
#last_inserted_id(result) private
#raw_execute(sql, name, async: false, allow_retry: false, materialize_transactions: true) private
#returning_column_values(result) private
#select(sql, name = nil, binds = [], prepare: false, async: false, allow_retry: false) private

Returns an ::ActiveRecord::Result instance.
#single_value_from_rows(rows) private
#with_multi_statements private
#cacheable_query(klass, arel) Internal use only

This is used in the ::ActiveRecord::StatementCache object.
#exec_insert_all(sql, name) Internal use only
#exec_restart_db_transaction Internal use only
#exec_rollback_db_transaction Internal use only
#explain(arel, binds = [], options = []) Internal use only
#internal_exec_query(sql, name = "SQL", binds = [], prepare: false, async: false, allow_retry: false) Internal use only
#mark_transaction_written_if_write(sql) Internal use only
#query(sql, name = nil) Internal use only
#query_value(sql, name = nil) Internal use only
#query_values(sql, name = nil) Internal use only
#reset_transaction(restore: false) Internal use only
#truncate_tables(*table_names) Internal use only
#with_yaml_fallback(value) Internal use only

::ActiveRecord::Fixture value is quoted by ::Arel, however scalar values are not quotable.
#sql_for_insert(sql, pk, binds, returning) private Internal use only
#to_sql_and_binds(arel_or_sql_string, binds = [], preparable = nil, allow_retry = false) private Internal use only

Instance Attribute Details

#begin_transaction (readonly)

[ GitHub ]

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


delegate :within_new_transaction, :open_transactions, :current_transaction, :begin_transaction,
         :commit_transaction, :rollback_transaction, :materialize_transactions,
         :disable_lazy_transactions!, :enable_lazy_transactions!, :dirty_current_transaction,
         to: :transaction_manager

#commit_transaction (readonly)

[ GitHub ]

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


delegate :within_new_transaction, :open_transactions, :current_transaction, :begin_transaction,
         :commit_transaction, :rollback_transaction, :materialize_transactions,
         :disable_lazy_transactions!, :enable_lazy_transactions!, :dirty_current_transaction,
         to: :transaction_manager

#current_transaction (readonly)

[ GitHub ]

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


delegate :within_new_transaction, :open_transactions, :current_transaction, :begin_transaction,
         :commit_transaction, :rollback_transaction, :materialize_transactions,
         :disable_lazy_transactions!, :enable_lazy_transactions!, :dirty_current_transaction,
         to: :transaction_manager

#dirty_current_transaction (readonly)

[ GitHub ]

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


delegate :within_new_transaction, :open_transactions, :current_transaction, :begin_transaction,
         :commit_transaction, :rollback_transaction, :materialize_transactions,
         :disable_lazy_transactions!, :enable_lazy_transactions!, :dirty_current_transaction,
         to: :transaction_manager

#materialize_transactions (readonly)

[ GitHub ]

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


delegate :within_new_transaction, :open_transactions, :current_transaction, :begin_transaction,
         :commit_transaction, :rollback_transaction, :materialize_transactions,
         :disable_lazy_transactions!, :enable_lazy_transactions!, :dirty_current_transaction,
         to: :transaction_manager

#open_transactions (readonly)

[ GitHub ]

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


delegate :within_new_transaction, :open_transactions, :current_transaction, :begin_transaction,
         :commit_transaction, :rollback_transaction, :materialize_transactions,
         :disable_lazy_transactions!, :enable_lazy_transactions!, :dirty_current_transaction,
         to: :transaction_manager

#rollback_transaction (readonly)

[ GitHub ]

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


delegate :within_new_transaction, :open_transactions, :current_transaction, :begin_transaction,
         :commit_transaction, :rollback_transaction, :materialize_transactions,
         :disable_lazy_transactions!, :enable_lazy_transactions!, :dirty_current_transaction,
         to: :transaction_manager

#transaction_manager (readonly)

This method is for internal use only.

[ GitHub ]

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


attr_reader :transaction_manager # :nodoc:

#transaction_open? ⇒ `Boolean` (readonly)

[ GitHub ]

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


def transaction_open?
  current_transaction.open?
end

#within_new_transaction (readonly)

[ GitHub ]

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


delegate :within_new_transaction, :open_transactions, :current_transaction, :begin_transaction,
         :commit_transaction, :rollback_transaction, :materialize_transactions,
         :disable_lazy_transactions!, :enable_lazy_transactions!, :dirty_current_transaction,
         to: :transaction_manager

Instance Method Details

#add_transaction_record(record, ensure_finalize = true)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 407


def add_transaction_record(record, ensure_finalize = true)
  current_transaction.add_record(record, ensure_finalize)
end

#arel_from_relation(relation) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 685


def arel_from_relation(relation)
  if relation.is_a?(Relation)
    relation.arel
  else
    relation
  end
end

#begin_db_transaction

Begins the transaction (and turns off auto-committing).

[ GitHub ]

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


def begin_db_transaction()    end

#begin_isolated_db_transaction(isolation)

Begins the transaction with the isolation level set. Raises an error by default; adapters that support setting the isolation level should implement this method.

Raises:

(ActiveRecord::TransactionIsolationError)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 426


def begin_isolated_db_transaction(isolation)
  raise ActiveRecord::TransactionIsolationError, "adapter does not support setting transaction isolation"
end

#build_fixture_sql(fixtures, table_name) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 558


def build_fixture_sql(fixtures, table_name)
  columns = schema_cache.columns_hash(table_name).reject { |_, column| supports_virtual_columns? && column.virtual? }

  values_list = fixtures.map do |fixture|
    fixture = fixture.stringify_keys

    unknown_columns = fixture.keys - columns.keys
    if unknown_columns.any?
      raise Fixture::FixtureError, %(table "#{table_name}" has no columns named #{unknown_columns.map(&:inspect).join(', ')}.)
    end

    columns.map do |name, column|
      if fixture.key?(name)
        type = lookup_cast_type_from_column(column)
        with_yaml_fallback(type.serialize(fixture[name]))
      else
        default_insert_value(column)
      end
    end
  end

  table = Arel::Table.new(table_name)
  manager = Arel::InsertManager.new(table)

  if values_list.size == 1
    values = values_list.shift
    new_values = []
    columns.each_key.with_index { |column, i|
      unless values[i].equal?(DEFAULT_INSERT_VALUE)
        new_values << values[i]
        manager.columns << table[column]
      end
    }
    values_list << new_values
  else
    columns.each_key { |column| manager.columns << table[column] }
  end

  manager.values = manager.create_values_list(values_list)
  visitor.compile(manager.ast)
end

#build_fixture_statements(fixture_set) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 600


def build_fixture_statements(fixture_set)
  fixture_set.filter_map do |table_name, fixtures|
    next if fixtures.empty?
    build_fixture_sql(fixtures, table_name)
  end
end

#build_truncate_statement(table_name) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 607


def build_truncate_statement(table_name)
  "TRUNCATE TABLE #{quote_table_name(table_name)}"
end

#build_truncate_statements(table_names) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 611


def build_truncate_statements(table_names)
  table_names.map do |table_name|
    build_truncate_statement(table_name)
  end
end

#cacheable_query(klass, arel)

This method is for internal use only.

This is used in the ::ActiveRecord::StatementCache object. It returns an object that can be used to query the database repeatedly.

[ GitHub ]

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


def cacheable_query(klass, arel) # :nodoc:
  if prepared_statements
    sql, binds = visitor.compile(arel.ast, collector)
    query = klass.query(sql)
  else
    collector = klass.partial_query_collector
    parts, binds = visitor.compile(arel.ast, collector)
    query = klass.partial_query(parts)
  end
  [query, binds]
end

#combine_multi_statements(total_sql) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 621


def combine_multi_statements(total_sql)
  total_sql.join(";\n")
end

#commit_db_transaction

Commits the transaction (and turns on auto-committing).

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 431


def commit_db_transaction()   end

#create(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = [], returning: nil)

Alias for #insert.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 203


alias create insert

#default_insert_value(column) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 554


def default_insert_value(column)
  DEFAULT_INSERT_VALUE
end

#default_sequence_name(table, column)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 453


def default_sequence_name(table, column)
  nil
end

#delete(arel, name = nil, binds = [])

Executes the delete statement and returns the number of rows affected.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 212


def delete(arel, name = nil, binds = [])
  sql, binds = to_sql_and_binds(arel, binds)
  exec_delete(sql, name, binds)
end

#disable_lazy_transactions!

[ GitHub ]

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


delegate :within_new_transaction, :open_transactions, :current_transaction, :begin_transaction,
         :commit_transaction, :rollback_transaction, :materialize_transactions,
         :disable_lazy_transactions!, :enable_lazy_transactions!, :dirty_current_transaction,
         to: :transaction_manager

#empty_insert_statement_value(primary_key = nil)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 485


def empty_insert_statement_value(primary_key = nil)
  "DEFAULT VALUES"
end

#enable_lazy_transactions!

[ GitHub ]

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


delegate :within_new_transaction, :open_transactions, :current_transaction, :begin_transaction,
         :commit_transaction, :rollback_transaction, :materialize_transactions,
         :disable_lazy_transactions!, :enable_lazy_transactions!, :dirty_current_transaction,
         to: :transaction_manager

#exec_delete(sql, name = nil, binds = [])

Executes delete sql statement in the context of this connection using binds as the bind substitutes. name is logged along with the executed sql statement.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 165


def exec_delete(sql, name = nil, binds = [])
  internal_exec_query(sql, name, binds)
end

#exec_insert(sql, name = nil, binds = [], pk = nil, sequence_name = nil, returning: nil)

Executes insert sql statement in the context of this connection using binds as the bind substitutes. name is logged along with the executed sql statement. Some adapters support the returning keyword argument which allows to control the result of the query: nil is the default value and maintains default behavior. If an array of column names is passed - the result will contain values of the specified columns from the inserted row.

[ GitHub ]

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


def exec_insert(sql, name = nil, binds = [], pk = nil, sequence_name = nil, returning: nil)
  sql, binds = sql_for_insert(sql, pk, binds, returning)
  internal_exec_query(sql, name, binds)
end

#exec_insert_all(sql, name)

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 176


def exec_insert_all(sql, name) # :nodoc:
  internal_exec_query(sql, name)
end

#exec_query(sql, name = "SQL", binds = [], prepare: false)

Executes sql statement in the context of this connection using binds as the bind substitutes. name is logged along with the executed sql statement.

Note: the query is assumed to have side effects and the query cache will be cleared. If the query is read-only, consider using #select_all instead.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 147


def exec_query(sql, name = "SQL", binds = [], prepare: false)
  internal_exec_query(sql, name, binds, prepare: prepare)
end

#exec_restart_db_transaction

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 447


def exec_restart_db_transaction() end # :nodoc:

#exec_rollback_db_transaction

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 441


def exec_rollback_db_transaction() end # :nodoc:

#exec_update(sql, name = nil, binds = [])

Executes update sql statement in the context of this connection using binds as the bind substitutes. name is logged along with the executed sql statement.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 172


def exec_update(sql, name = nil, binds = [])
  internal_exec_query(sql, name, binds)
end

#execute(sql, name = nil, allow_retry: false)

Executes the SQL statement in the context of this connection and returns the raw result from the connection adapter.

Setting allow_retry to true causes the db to reconnect and retry executing the SQL statement in case of a connection-related exception. This option should only be enabled for known idempotent queries.

Note: the query is assumed to have side effects and the query cache will be cleared. If the query is read-only, consider using #select_all instead.

Note: depending on your database connector, the result returned by this method may be manually memory managed. Consider using #exec_query wrapper instead.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 136


def execute(sql, name = nil, allow_retry: false)
  internal_execute(sql, name, allow_retry: allow_retry)
end

#execute_batch(statements, name = nil) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 541


def execute_batch(statements, name = nil)
  statements.each do |statement|
    internal_execute(statement, name)
  end
end

#explain(arel, binds = [], options = [])

This method is for internal use only.

Raises:

(NotImplementedError)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 180


def explain(arel, binds = [], options = []) # :nodoc:
  raise NotImplementedError
end

#extract_table_ref_from_insert_sql(sql) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 693


def extract_table_ref_from_insert_sql(sql)
  if sql =~ /into\s("[A-Za-z0-9_."\[\]\s]"|[A-Za-z0-9_."\[\]])\s*/im
    $1.delete('"').strip
  end
end

#high_precision_current_timestamp

Returns an ::Arel SQL literal for the CURRENT_TIMESTAMP for usage with arbitrary precision date/time columns.

Adapters supporting datetime with precision should override this to provide as much precision as is available.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 523


def high_precision_current_timestamp
  HIGH_PRECISION_CURRENT_TIMESTAMP
end

#initialize

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 6


def initialize
  super
  reset_transaction
end

#insert(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = [], returning: nil) Also known as: #create

Executes an INSERT query and returns the new record’s ID

id_value will be returned unless the value is nil, in which case the database will attempt to calculate the last inserted id and return that value.

If the next id was calculated in advance (as in Oracle), it should be passed in as id_value. Some adapters support the returning keyword argument which allows defining the return value of the method: nil is the default value and maintains default behavior. If an array of column names is passed - an array of is returned from the method representing values of the specified columns from the inserted row.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 195


def insert(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = [], returning: nil)
  sql, binds = to_sql_and_binds(arel, binds)
  value = exec_insert(sql, name, binds, pk, sequence_name, returning: returning)

  return returning_column_values(value) unless returning.nil?

  id_value || last_inserted_id(value)
end

#insert_fixture(fixture, table_name)

Inserts the given fixture into the table. Overridden in adapters that require something beyond a simple insert (e.g. Oracle). Most of adapters should implement #insert_fixtures_set that leverages bulk SQL insert. We keep this method to provide fallback for databases like SQLite that do not support bulk inserts.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 467


def insert_fixture(fixture, table_name)
  execute(build_fixture_sql(Array.wrap(fixture), table_name), "Fixture Insert")
end

#insert_fixtures_set(fixture_set, tables_to_delete = [])

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 471


def insert_fixtures_set(fixture_set, tables_to_delete = [])
  fixture_inserts = build_fixture_statements(fixture_set)
  table_deletes = tables_to_delete.map { |table| "DELETE FROM #{quote_table_name(table)}" }
  statements = table_deletes + fixture_inserts

  with_multi_statements do
    transaction(requires_new: true) do
      disable_referential_integrity do
        execute_batch(statements, "Fixtures Load")
      end
    end
  end
end

#internal_exec_query(sql, name = "SQL", binds = [], prepare: false, async: false, allow_retry: false)

This method is for internal use only.

Raises:

(NotImplementedError)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 527


def internal_exec_query(sql, name = "SQL", binds = [], prepare: false, async: false, allow_retry: false) # :nodoc:
  raise NotImplementedError
end

#internal_execute(sql, name = "SCHEMA", allow_retry: false, materialize_transactions: true) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 532


def internal_execute(sql, name = "SCHEMA", allow_retry: false, materialize_transactions: true)
  sql = transform_query(sql)
  check_if_write_query(sql)

  mark_transaction_written_if_write(sql)

  raw_execute(sql, name, allow_retry: allow_retry, materialize_transactions: materialize_transactions)
end

#last_inserted_id(result) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 672


def last_inserted_id(result)
  single_value_from_rows(result.rows)
end

#mark_transaction_written_if_write(sql)

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 374


def mark_transaction_written_if_write(sql) # :nodoc:
  transaction = current_transaction
  if transaction.open?
    transaction.written ||= write_query?(sql)
  end
end

#query(sql, name = nil)

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 113


def query(sql, name = nil) # :nodoc:
  internal_exec_query(sql, name).rows
end

#query_value(sql, name = nil)

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 105


def query_value(sql, name = nil) # :nodoc:
  single_value_from_rows(query(sql, name))
end

#query_values(sql, name = nil)

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 109


def query_values(sql, name = nil) # :nodoc:
  query(sql, name).map(&:first)
end

#raw_execute(sql, name, async: false, allow_retry: false, materialize_transactions: true) (private)

Raises:

(NotImplementedError)

[ GitHub ]

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


def raw_execute(sql, name, async: false, allow_retry: false, materialize_transactions: true)
  raise NotImplementedError
end

#reset_sequence!(table, column, sequence = nil)

Set the sequence to the max value of the table’s column.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 458


def reset_sequence!(table, column, sequence = nil)
  # Do nothing by default. Implement for PostgreSQL, Oracle, ...
end

#reset_transaction(restore: false)

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 385


def reset_transaction(restore: false) # :nodoc:
  # Store the existing transaction state to the side
  old_state = @transaction_manager if restore && @transaction_manager&.restorable?

  @transaction_manager = ConnectionAdapters::TransactionManager.new(self)

  if block_given?
    # Reconfigure the connection without any transaction state in the way
    result = yield

    # Now the connection's fully established, we can swap back
    if old_state
      @transaction_manager = old_state
      @transaction_manager.restore_transactions
    end

    result
  end
end

#restart_db_transaction

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 443


def restart_db_transaction
  exec_restart_db_transaction
end

#returning_column_values(result) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 676


def returning_column_values(result)
  [last_inserted_id(result)]
end

#rollback_db_transaction

Rolls back the transaction (and turns on auto-committing). Must be done if the transaction block raises an exception or returns false.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 435


def rollback_db_transaction
  exec_rollback_db_transaction
rescue ActiveRecord::ConnectionNotEstablished, ActiveRecord::ConnectionFailed
  # Connection's gone; that counts as a rollback
end

#rollback_to_savepoint(name = nil)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 449


def rollback_to_savepoint(name = nil)
  exec_rollback_to_savepoint(name)
end

#sanitize_limit(limit)

Sanitizes the given LIMIT parameter in order to prevent SQL injection.

The limit may be anything that can evaluate to a string via #to_s. It should look like an integer, or an ::Arel SQL literal.

Returns Integer and ::Arel::Nodes::SqlLiteral limits as is.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 495


def sanitize_limit(limit)
  if limit.is_a?(Integer) || limit.is_a?(Arel::Nodes::SqlLiteral)
    limit
  else
    Integer(limit)
  end
end

#select(sql, name = nil, binds = [], prepare: false, async: false, allow_retry: false) (private)

Returns an ::ActiveRecord::Result instance.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 626


def select(sql, name = nil, binds = [], prepare: false, async: false, allow_retry: false)
  if async && async_enabled?
    if current_transaction.joinable?
      raise AsynchronousQueryInsideTransactionError, "Asynchronous queries are not allowed inside transactions"
    end

    future_result = async.new(
      pool,
      sql,
      name,
      binds,
      prepare: prepare,
    )
    if supports_concurrent_connections? && current_transaction.closed?
      future_result.schedule!(ActiveRecord::Base.asynchronous_queries_session)
    else
      future_result.execute!(self)
    end
    return future_result
  end

  result = internal_exec_query(sql, name, binds, prepare: prepare, allow_retry: allow_retry)
  if async
    FutureResult.wrap(result)
  else
    result
  end
end

#select_all(arel, name = nil, binds = [], preparable: nil, async: false, allow_retry: false)

Returns an ::ActiveRecord::Result instance.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 69


def select_all(arel, name = nil, binds = [], preparable: nil, async: false, allow_retry: false)
  arel = arel_from_relation(arel)
  sql, binds, preparable, allow_retry = to_sql_and_binds(arel, binds, preparable, allow_retry)

  select(sql, name, binds,
    prepare: prepared_statements && preparable,
    async: async && FutureResult::SelectAll,
    allow_retry: allow_retry
  )
rescue ::RangeError
  ActiveRecord::Result.empty(async: async)
end

#select_one(arel, name = nil, binds = [], async: false)

Returns a record hash with the column names as keys and column values as values.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 84


def select_one(arel, name = nil, binds = [], async: false)
  select_all(arel, name, binds, async: async).then(&:first)
end

#select_rows(arel, name = nil, binds = [], async: false)

Returns an array of arrays containing the field values. Order is the same as that returned by columns.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 101


def select_rows(arel, name = nil, binds = [], async: false)
  select_all(arel, name, binds, async: async).then(&:rows)
end

#select_value(arel, name = nil, binds = [], async: false)

Returns a single value from a record

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 89


def select_value(arel, name = nil, binds = [], async: false)
  select_rows(arel, name, binds, async: async).then { |rows| single_value_from_rows(rows) }
end

#select_values(arel, name = nil, binds = [])

Returns an array of the values of the first column in a select:

select_values("SELECT id FROM companies LIMIT 3") => [1,2,3]

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 95


def select_values(arel, name = nil, binds = [])
  select_rows(arel, name, binds).map(&:first)
end

#single_value_from_rows(rows) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 680


def single_value_from_rows(rows)
  row = rows.first
  row && row.first
end

#sql_for_insert(sql, pk, binds, returning) (private)

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 655


def sql_for_insert(sql, pk, binds, returning) # :nodoc:
  if supports_insert_returning?
    if pk.nil?
      # Extract the table from the insert sql. Yuck.
      table_ref = extract_table_ref_from_insert_sql(sql)
      pk = primary_key(table_ref) if table_ref
    end

    returning_columns = returning || Array(pk)

    returning_columns_statement = returning_columns.map { |c| quote_column_name(c) }.join(", ")
    sql = "#{sql} RETURNING #{returning_columns_statement}" if returning_columns.any?
  end

  [sql, binds]
end

#to_sql(arel_or_sql_string, binds = [])

Converts an arel AST to SQL

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 12


def to_sql(arel_or_sql_string, binds = [])
  sql, _ = to_sql_and_binds(arel_or_sql_string, binds)
  sql
end

#to_sql_and_binds(arel_or_sql_string, binds = [], preparable = nil, allow_retry = false) (private)

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 17


def to_sql_and_binds(arel_or_sql_string, binds = [], preparable = nil, allow_retry = false) # :nodoc:
  # Arel::TreeManager -> Arel::Node
  if arel_or_sql_string.respond_to?(:ast)
    arel_or_sql_string = arel_or_sql_string.ast
  end

  if Arel.arel_node?(arel_or_sql_string) && !(String === arel_or_sql_string)
    unless binds.empty?
      raise "Passing bind parameters with an arel AST is forbidden. " \
        "The values must be stored on the AST directly"
    end

    collector = collector()
    collector.retryable = true

    if prepared_statements
      collector.preparable = true
      sql, binds = visitor.compile(arel_or_sql_string, collector)

      if binds.length > bind_params_length
        unprepared_statement do
          return to_sql_and_binds(arel_or_sql_string)
        end
      end
      preparable = collector.preparable
    else
      sql = visitor.compile(arel_or_sql_string, collector)
    end
    allow_retry = collector.retryable
    [sql.freeze, binds, preparable, allow_retry]
  else
    arel_or_sql_string = arel_or_sql_string.dup.freeze unless arel_or_sql_string.frozen?
    [arel_or_sql_string, binds, preparable, allow_retry]
  end
end

#transaction(requires_new: nil, isolation: nil, joinable: true, &block)

Runs the given block in a database transaction, and returns the result of the block.

Transaction callbacks

#transaction yields an ::ActiveRecord::Transaction object on which it is possible to register callback:

ActiveRecord::Base.transaction do |transaction|
  transaction.before_commit { puts "before commit!" }
  transaction.after_commit { puts "after commit!" }
  transaction.after_rollback { puts "after rollback!" }
end

Nested transactions support

#transaction calls can be nested. By default, this makes all database statements in the nested transaction block become part of the parent transaction. For example, the following behavior may be surprising:

ActiveRecord::Base.transaction do
  Post.create(title: 'first')
  ActiveRecord::Base.transaction do
    Post.create(title: 'second')
    raise ActiveRecord::Rollback
  end
end

This creates both “first” and “second” posts. Reason is the ::ActiveRecord::Rollback exception in the nested block does not issue a ROLLBACK. Since these exceptions are captured in transaction blocks, the parent block does not see it and the real transaction is committed.

Most databases don’t support true nested transactions. At the time of writing, the only database that supports true nested transactions that we’re aware of, is MS-SQL.

In order to get around this problem, #transaction will emulate the effect of nested transactions, by using savepoints: dev.mysql.com/doc/refman/en/savepoint.html.

It is safe to call this method if a database transaction is already open, i.e. if #transaction is called within another #transaction block. In case of a nested call, #transaction will behave as follows:

The block will be run without doing anything. All database statements that happen within the block are effectively appended to the already open database transaction.
However, if :requires_new is set, the block will be wrapped in a database savepoint acting as a sub-transaction.

In order to get a ROLLBACK for the nested transaction you may ask for a real sub-transaction by passing requires_new: true. If anything goes wrong, the database rolls back to the beginning of the sub-transaction without rolling back the parent transaction. If we add it to the previous example:

ActiveRecord::Base.transaction do
  Post.create(title: 'first')
  ActiveRecord::Base.transaction(requires_new: true) do
    Post.create(title: 'second')
    raise ActiveRecord::Rollback
  end
end

only post with title “first” is created.

See ::ActiveRecord::Transactions to learn more.

Caveats

MySQL doesn’t support DDL transactions. If you perform a DDL operation, then any created savepoints will be automatically released. For example, if you’ve created a savepoint, then you execute a CREATE TABLE statement, then the savepoint that was created will be automatically released.

This means that, on MySQL, you shouldn’t execute DDL operations inside a #transaction call that you know might create a savepoint. Otherwise, #transaction will raise exceptions when it tries to release the already-automatically-released savepoints:

Model.lease_connection.transaction do  # BEGIN
  Model.lease_connection.transaction(requires_new: true) do  # CREATE SAVEPOINT active_record_1
    Model.lease_connection.create_table(...)
    # active_record_1 now automatically released
  end  # RELEASE SAVEPOINT active_record_1  <--- BOOM! database error!
end

Transaction isolation

If your database supports setting the isolation level for a transaction, you can set it like so:

Post.transaction(isolation: :serializable) do
  # ...
end

Valid isolation levels are:

:read_uncommitted
:read_committed
:repeatable_read
:serializable

You should consult the documentation for your database to understand the semantics of these different levels:

An ::ActiveRecord::TransactionIsolationError will be raised if:

The adapter does not support setting the isolation level
You are joining an existing open transaction
You are creating a nested (savepoint) transaction

The mysql2, trilogy, and postgresql adapters support setting the transaction isolation level.

:args: (requires_new: nil, isolation: nil, &block)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 354


def transaction(requires_new: nil, isolation: nil, joinable: true, &block)
  if !requires_new && current_transaction.joinable?
    if isolation
      raise ActiveRecord::TransactionIsolationError, "cannot set isolation when joining a transaction"
    end
    yield current_transaction
  else
    transaction_manager.within_new_transaction(isolation: isolation, joinable: joinable, &block)
  end
rescue ActiveRecord::Rollback
  # rollbacks are silently swallowed
end

#transaction_isolation_levels

[ GitHub ]

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


def transaction_isolation_levels
  {
    read_uncommitted: "READ UNCOMMITTED",
    read_committed:   "READ COMMITTED",
    repeatable_read:  "REPEATABLE READ",
    serializable:     "SERIALIZABLE"
  }
end

#truncate(table_name, name = nil)

Executes the truncate statement.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 218


def truncate(table_name, name = nil)
  execute(build_truncate_statement(table_name), name)
end

#truncate_tables(*table_names)

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 222


def truncate_tables(*table_names) # :nodoc:
  table_names -= [pool.schema_migration.table_name, pool.internal_metadata.table_name]

  return if table_names.empty?

  with_multi_statements do
    disable_referential_integrity do
      statements = build_truncate_statements(table_names)
      execute_batch(statements, "Truncate Tables")
    end
  end
end

#update(arel, name = nil, binds = [])

Executes the update statement and returns the number of rows affected.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 206


def update(arel, name = nil, binds = [])
  sql, binds = to_sql_and_binds(arel, binds)
  exec_update(sql, name, binds)
end

#with_multi_statements (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 617


def with_multi_statements
  yield
end

#with_yaml_fallback(value)

This method is for internal use only.

::ActiveRecord::Fixture value is quoted by ::Arel, however scalar values are not quotable. In this case we want to convert the column value to YAML.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 506


def with_yaml_fallback(value) # :nodoc:
  if value.is_a?(Hash) || value.is_a?(Array)
    YAML.dump(value)
  else
    value
  end
end

#write_query?(sql) ⇒ `Boolean`

Determines whether the SQL statement is a write query.

Raises:

(NotImplementedError)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 118


def write_query?(sql)
  raise NotImplementedError
end

Module: ActiveRecord::ConnectionAdapters::DatabaseStatements

Constant Summary

Instance Attribute Summary

Instance Method Summary

Instance Attribute Details

#begin_transaction (readonly)

#commit_transaction (readonly)

#current_transaction (readonly)

#dirty_current_transaction (readonly)

#materialize_transactions (readonly)

#open_transactions (readonly)

#rollback_transaction (readonly)

#transaction_manager (readonly)

#transaction_open? ⇒ Boolean (readonly)

#within_new_transaction (readonly)

Instance Method Details

#add_transaction_record(record, ensure_finalize = true)

#arel_from_relation(relation) (private)

#begin_db_transaction

#begin_isolated_db_transaction(isolation)

#build_fixture_sql(fixtures, table_name) (private)

#build_fixture_statements(fixture_set) (private)

#build_truncate_statement(table_name) (private)

#build_truncate_statements(table_names) (private)

#cacheable_query(klass, arel)

#combine_multi_statements(total_sql) (private)

#commit_db_transaction

#create(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = [], returning: nil)

#default_insert_value(column) (private)

#default_sequence_name(table, column)

#delete(arel, name = nil, binds = [])

#disable_lazy_transactions!

#empty_insert_statement_value(primary_key = nil)

#enable_lazy_transactions!

#exec_delete(sql, name = nil, binds = [])

#exec_insert(sql, name = nil, binds = [], pk = nil, sequence_name = nil, returning: nil)

#exec_insert_all(sql, name)

#exec_query(sql, name = "SQL", binds = [], prepare: false)

#exec_restart_db_transaction

#exec_rollback_db_transaction

#exec_update(sql, name = nil, binds = [])

#execute(sql, name = nil, allow_retry: false)

#execute_batch(statements, name = nil) (private)

#explain(arel, binds = [], options = [])

#extract_table_ref_from_insert_sql(sql) (private)

#high_precision_current_timestamp

#initialize

#insert(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = [], returning: nil) Also known as: #create

#insert_fixture(fixture, table_name)

#insert_fixtures_set(fixture_set, tables_to_delete = [])

#internal_exec_query(sql, name = "SQL", binds = [], prepare: false, async: false, allow_retry: false)

#internal_execute(sql, name = "SCHEMA", allow_retry: false, materialize_transactions: true) (private)

#last_inserted_id(result) (private)

#mark_transaction_written_if_write(sql)

#query(sql, name = nil)

#query_value(sql, name = nil)

#query_values(sql, name = nil)

#raw_execute(sql, name, async: false, allow_retry: false, materialize_transactions: true) (private)

#reset_sequence!(table, column, sequence = nil)

#reset_transaction(restore: false)

#restart_db_transaction

#returning_column_values(result) (private)

#rollback_db_transaction

#rollback_to_savepoint(name = nil)

#sanitize_limit(limit)

#select(sql, name = nil, binds = [], prepare: false, async: false, allow_retry: false) (private)

#select_all(arel, name = nil, binds = [], preparable: nil, async: false, allow_retry: false)

#select_one(arel, name = nil, binds = [], async: false)

#select_rows(arel, name = nil, binds = [], async: false)

#select_value(arel, name = nil, binds = [], async: false)

#select_values(arel, name = nil, binds = [])

#single_value_from_rows(rows) (private)

#sql_for_insert(sql, pk, binds, returning) (private)

#to_sql(arel_or_sql_string, binds = [])

#to_sql_and_binds(arel_or_sql_string, binds = [], preparable = nil, allow_retry = false) (private)

#transaction(requires_new: nil, isolation: nil, joinable: true, &block)

Transaction callbacks

Nested transactions support

Caveats

Transaction isolation

#transaction_open? ⇒ `Boolean` (readonly)

#write_query?(sql) ⇒ `Boolean`