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 619
```
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 588
```
Arel.sql("CURRENT_TIMESTAMP", retryable: true).freeze
```

TRANSACTION_ISOLATION_LEVELS = private
# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 487

{
  read_uncommitted: "READ UNCOMMITTED",
  read_committed:   "READ COMMITTED",
  repeatable_read:  "REPEATABLE READ",
  serializable:     "SERIALIZABLE"
}.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_isolation_level

Hook point called after an isolated DB transaction is committed or rolled back.
#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)
#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.
#affected_rows(raw_result) private
#arel_from_relation(relation) private
#build_delete_from_statements(table_names) 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
#cast_result(raw_result) private

Receive a native adapter result object and returns an ::ActiveRecord::Result object.
#combine_multi_statements(total_sql) private
#execute_batch(statements, name = nil, **kwargs) private
#extract_table_ref_from_insert_sql(sql) private
#handle_warnings(raw_result, sql) private
#internal_build_intent(sql, name = "SQL", binds = [], prepare: false, allow_retry: false, materialize_transactions: true, &block) private
#last_inserted_id(result) private
#perform_query(raw_connection, intent) private
#returning_column_values(result) private
#single_value_from_rows(rows) private
#_exec_insert(intent, pk = nil, sequence_name = nil, returning: nil) Internal use only
#begin_deferred_transaction(isolation_level = nil) Internal use only
#cacheable_query(klass, arel) Internal use only

This is used in the ::ActiveRecord::StatementCache object.
#default_insert_value(column) Internal use only
#empty_all_tables Internal use only
#exec_insert_all(sql, name) Internal use only
#exec_restart_db_transaction Internal use only
#exec_rollback_db_transaction Internal use only
#execute_intent(intent) Internal use only

Lowest-level abstract execution of a query, called only from the intent itself.
#explain(arel, binds = [], options = []) Internal use only
#query_all(sql, name = "SCHEMA", allow_retry: true, materialize_transactions: false) Internal use only
#query_command(sql, name = nil, allow_retry: false, materialize_transactions: true) Internal use only
#query_one Internal use only
#query_rows Internal use only
#query_value Internal use only
#query_values Internal use only
#reset_transaction(restore: false) Internal use only
#to_sql_and_binds(arel_or_sql_string, binds = [], preparable = nil, allow_retry = 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

Instance Attribute Details

#begin_transaction (readonly)

[ GitHub ]

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


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 441


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 441


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 441


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 441


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 441


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 441


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 439


attr_reader :transaction_manager # :nodoc:

#transaction_open? ⇒ `Boolean` (readonly)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 446


def transaction_open?
  current_transaction.open?
end

#within_new_transaction (readonly)

[ GitHub ]

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


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

#_exec_insert(intent, pk = nil, sequence_name = nil, returning: nil)

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 193


def _exec_insert(intent, pk = nil, sequence_name = nil, returning: nil) # :nodoc:
  sql, binds = sql_for_insert(intent.raw_sql, pk, intent.binds, returning)
  intent.raw_sql = sql
  intent.binds = binds

  intent.execute!
  intent.cast_result
end

#add_transaction_record(record, ensure_finalize = true)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 472


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

#affected_rows(raw_result) (private)

Raises:

(NotImplementedError)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 634


def affected_rows(raw_result)
  raise NotImplementedError
end

#arel_from_relation(relation) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 766


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 477


def begin_db_transaction()    end

#begin_deferred_transaction(isolation_level = nil)

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 479


def begin_deferred_transaction(isolation_level = nil) # :nodoc:
  if isolation_level
    begin_isolated_db_transaction(isolation_level)
  else
    begin_db_transaction
  end
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 502


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

#build_delete_from_statements(table_names) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 726


def build_delete_from_statements(table_names)
  table_names.map do |table_name|
    "DELETE FROM #{quote_table_name(table_name)}"
  end
end

#build_fixture_sql(fixtures, table_name) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 667


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)
        # TODO: Remove fetch_cast_type and the need for connection after we release 8.1.
        with_yaml_fallback(column.fetch_cast_type(self).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 709


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 716


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 720


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 55


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

#cast_result(raw_result) (private)

Receive a native adapter result object and returns an ::ActiveRecord::Result object.

Raises:

(NotImplementedError)

[ GitHub ]

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


def cast_result(raw_result)
  raise NotImplementedError
end

#combine_multi_statements(total_sql) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 732


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 516


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 252


alias create insert

#default_insert_value(column)

This method is for internal use only.

[ GitHub ]

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


def default_insert_value(column) # :nodoc:
  DEFAULT_INSERT_VALUE
end

#default_sequence_name(table, column)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 538


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 263


def delete(arel, name = nil, binds = [])
  intent = QueryIntent.new(adapter: self, arel: arel, name: name, binds: binds)

  intent.execute!
  intent.affected_rows
end

#disable_lazy_transactions!

[ GitHub ]

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


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_all_tables

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 568


def empty_all_tables # :nodoc:
  truncate_tables(*tables)
end

#empty_insert_statement_value(primary_key = nil)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 572


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 441


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 205


def exec_delete(sql, name = nil, binds = [])
  intent = internal_build_intent(sql, name, binds)
  intent.execute!
  intent.affected_rows
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 187


def exec_insert(sql, name = nil, binds = [], pk = nil, sequence_name = nil, returning: nil)
  intent = QueryIntent.new(adapter: self, raw_sql: sql, name: name, binds: binds)

  _exec_insert(intent, pk, sequence_name, returning: returning)
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 222


def exec_insert_all(sql, name) # :nodoc:
  intent = internal_build_intent(sql, name)
  intent.execute!
  intent.cast_result
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 175


def exec_query(sql, name = "SQL", binds = [], prepare: false)
  intent = internal_build_intent(sql, name, binds, prepare: prepare)
  intent.execute!
  intent.cast_result
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 532


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 526


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 214


def exec_update(sql, name = nil, binds = [])
  intent = internal_build_intent(sql, name, binds)
  intent.execute!
  intent.affected_rows
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 162


def execute(sql, name = nil, allow_retry: false)
  intent = internal_build_intent(sql, name, allow_retry: allow_retry)
  intent.execute!
  intent.raw_result
end

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

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 650


def execute_batch(statements, name = nil, **kwargs)
  statements.each do |statement|
    intent = QueryIntent.new(
      adapter: self,
      processed_sql: statement,
      name: name,
      binds: kwargs[:binds] || [],
      prepare: kwargs[:prepare] || false,
      allow_retry: kwargs[:allow_retry] || false,
      materialize_transactions: kwargs[:materialize_transactions] != false,
      batch: kwargs[:batch] || false
    )
    intent.execute!
    intent.finish
  end
end

#execute_intent(intent)

This method is for internal use only.

Lowest-level abstract execution of a query, called only from the intent itself. Final wrapper around the subclass-specific #perform_query. Populates the calling intent’s raw_result.

[ GitHub ]

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


def execute_intent(intent) # :nodoc:
  log(intent) do |notification_payload|
    intent.notification_payload = notification_payload
    with_raw_connection(allow_retry: intent.allow_retry, materialize_transactions: intent.materialize_transactions) do |conn|
      result = perform_query(conn, intent)
      intent.raw_result = result
      handle_warnings(result, intent.processed_sql)
    end
  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 228


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 774


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

#handle_warnings(raw_result, sql) (private)

[ GitHub ]

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


def handle_warnings(raw_result, sql)
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 596


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 243


def insert(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = [], returning: nil)
  intent = QueryIntent.new(adapter: self, arel: arel, name: name, binds: binds)

  value = _exec_insert(intent, 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 552


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 556


def insert_fixtures_set(fixture_set, tables_to_delete = [])
  fixture_inserts = build_fixture_statements(fixture_set)
  table_deletes = build_delete_from_statements(tables_to_delete)
  statements = table_deletes + fixture_inserts

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

#internal_build_intent(sql, name = "SQL", binds = [], prepare: false, allow_retry: false, materialize_transactions: true, &block) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 638


def internal_build_intent(sql, name = "SQL", binds = [], prepare: false, allow_retry: false, materialize_transactions: true, &block)
  QueryIntent.new(
    adapter: self,
    raw_sql: sql,
    name: name,
    binds: binds,
    prepare: prepare,
    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 753


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

#perform_query(raw_connection, intent) (private)

Raises:

(NotImplementedError)

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 622


def perform_query(raw_connection, intent)
  raise NotImplementedError
end

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

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 131


def query_all(sql, name = "SCHEMA", allow_retry: true, materialize_transactions: false) # :nodoc:
  intent = internal_build_intent(sql, name, allow_retry:, materialize_transactions:)
  intent.execute!
  intent.cast_result
end

#query_command(sql, name = nil, allow_retry: false, materialize_transactions: true)

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 137


def query_command(sql, name = nil, allow_retry: false, materialize_transactions: true) # :nodoc:
  intent = internal_build_intent(sql, name, allow_retry: allow_retry, materialize_transactions: materialize_transactions)
  intent.execute!
  intent.finish
end

#query_one

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 123


def query_one(...) # :nodoc:
  query_all(...).first
end

#query_rows

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 127


def query_rows(...) # :nodoc:
  query_all(...).rows
end

#query_value

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 115


def query_value(...) # :nodoc:
  single_value_from_rows(query_rows(...))
end

#query_values

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 119


def query_values(...) # :nodoc:
  query_rows(...).map(&:first)
end

#reset_isolation_level

Hook point called after an isolated DB transaction is committed or rolled back. Most adapters don’t need to implement anything because the isolation level is set on a per transaction basis. But some databases like SQLite set it on a per connection level and need to explicitly reset it after commit or rollback.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 512


def reset_isolation_level
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 543


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 450


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 528


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 757


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 520


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 534


def rollback_to_savepoint(name = nil)
  exec_rollback_to_savepoint(name)
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 71


def select_all(arel, name = nil, binds = [], preparable: nil, async: false, allow_retry: false)
  arel = arel_from_relation(arel)
  intent = QueryIntent.new(
    adapter: self,
    arel: arel,
    name: name,
    binds: binds,
    prepare: preparable,
    allow_async: async,
    allow_retry: allow_retry
  )

  intent.execute!

  if async
    intent.future_result
  else
    intent.cast_result
  end
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 94


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 111


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 99


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 105


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 761


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 736


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)

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 405


def transaction(requires_new: nil, isolation: nil, joinable: true, &block)
  # If we're running inside the single, non-joinable transaction that
  # ActiveRecord::TestFixtures starts around each example (depth == 1),
  # an `isolation:` hint must be validated then ignored so that the
  # adapter isn't asked to change the isolation level mid-transaction.
  isolation_override = false
  if isolation && open_transactions == 1 && !current_transaction.joinable?
    iso = isolation.to_sym

    unless transaction_isolation_levels.include?(iso)
      raise ActiveRecord::TransactionIsolationError,
            "invalid transaction isolation level: #{iso.inspect}"
    end

    isolation_override = true
    old_isolation = current_transaction.isolation
    current_transaction.isolation = iso
    isolation = nil
  end

  if !requires_new && current_transaction.joinable?
    if isolation && current_transaction.isolation != isolation
      raise ActiveRecord::TransactionIsolationError, "cannot set isolation when joining a transaction"
    end
    yield current_transaction.user_transaction
  else
    within_new_transaction(isolation: isolation, joinable: joinable, &block)
  end
rescue ActiveRecord::Rollback
  # rollbacks are silently swallowed
ensure
  current_transaction.isolation = old_isolation if isolation_override
end

#transaction_isolation_levels

[ GitHub ]

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


def transaction_isolation_levels
  TRANSACTION_ISOLATION_LEVELS
end

#truncate(table_name, name = nil)

Executes the truncate statement.

[ GitHub ]

# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 271


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 275


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

  return if table_names.empty?

  disable_referential_integrity do
    statements = build_truncate_statements(table_names)
    execute_batch(statements, "Truncate Tables")
  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 255


def update(arel, name = nil, binds = [])
  intent = QueryIntent.new(adapter: self, arel: arel, name: name, binds: binds)

  intent.execute!
  intent.affected_rows
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 579


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 144


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

#_exec_insert(intent, pk = nil, sequence_name = nil, returning: nil)

#add_transaction_record(record, ensure_finalize = true)

#affected_rows(raw_result) (private)

#arel_from_relation(relation) (private)

#begin_db_transaction

#begin_deferred_transaction(isolation_level = nil)

#begin_isolated_db_transaction(isolation)

#build_delete_from_statements(table_names) (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)

#cacheable_query(klass, arel)

#cast_result(raw_result) (private)

#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)

#default_sequence_name(table, column)

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

#disable_lazy_transactions!

#empty_all_tables

#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, **kwargs) (private)

#execute_intent(intent)

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

#extract_table_ref_from_insert_sql(sql) (private)

#handle_warnings(raw_result, 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_build_intent(sql, name = "SQL", binds = [], prepare: false, allow_retry: false, materialize_transactions: true, &block) (private)

#last_inserted_id(result) (private)

#perform_query(raw_connection, intent) (private)

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

#query_command(sql, name = nil, allow_retry: false, materialize_transactions: true)

#query_one

#query_rows

#query_value

#query_values

#reset_isolation_level

#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)

#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)

#transaction_open? ⇒ `Boolean` (readonly)

#write_query?(sql) ⇒ `Boolean`