# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 6 def initialize super reset_transaction end
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 345 def add_transaction_record(record, ensure_finalize = true) current_transaction.add_record(record, ensure_finalize) end
Register a record with the current transaction so that its after_commit and after_rollback callbacks can be called.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 350 def begin_db_transaction() end
Begins the transaction (and turns off auto-committing).
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 364 def begin_isolated_db_transaction(isolation) raise ActiveRecord::TransactionIsolationError, "adapter does not support setting transaction isolation" end
Begins the transaction with the isolation level set. Raises an error by default; adapters that support setting the isolation level should implement this method.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 369 def commit_db_transaction() end
Commits the transaction (and turns on auto-committing).
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 383 def default_sequence_name(table, column) nil end
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 179 def delete(arel, name = nil, binds = []) sql, binds = to_sql_and_binds(arel, binds) exec_delete(sql, name, binds) end
Executes the delete statement and returns the number of rows affected.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 415 def empty_insert_statement_value(primary_key = nil) "DEFAULT VALUES" end
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 138 def exec_delete(sql, name = nil, binds = []) exec_query(sql, name, binds) end
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.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 130 def exec_insert(sql, name = nil, binds = [], pk = nil, sequence_name = nil) sql, binds = sql_for_insert(sql, pk, binds) exec_query(sql, name, binds) end
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.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 123 def exec_query(sql, name = "SQL", binds = [], prepare: false) raise NotImplementedError end
Executes sql statement in the context of this connection using binds as the bind substitutes. name is logged along with the executed sql statement.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 145 def exec_update(sql, name = nil, binds = []) exec_query(sql, name, binds) end
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.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 116 def execute(sql, name = nil) raise NotImplementedError end
Executes the SQL statement in the context of this connection and returns the raw result from the connection adapter. Note: depending on your database connector, the result returned by this method may be manually memory managed. Consider using the exec_query wrapper instead.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 453 def high_precision_current_timestamp HIGH_PRECISION_CURRENT_TIMESTAMP end
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.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 165 def insert(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = []) sql, binds = to_sql_and_binds(arel, binds) value = exec_insert(sql, name, binds, pk, sequence_name) id_value || last_inserted_id(value) end
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.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 397 def insert_fixture(fixture, table_name) execute(build_fixture_sql(Array.wrap(fixture), table_name), "Fixture Insert") end
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.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 401
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
disable_referential_integrity do
transaction(requires_new: true) do
execute_batch(statements, "Fixtures Load")
end
end
end
end # File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 388 def reset_sequence!(table, column, sequence = nil) # Do nothing by default. Implement for PostgreSQL, Oracle, ... end
Set the sequence to the max value of the table's column.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 373 def rollback_db_transaction exec_rollback_db_transaction end
Rolls back the transaction (and turns on auto-committing). Must be done if the transaction block raises an exception or returns false.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 379 def rollback_to_savepoint(name = nil) exec_rollback_to_savepoint(name) end
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 425
def sanitize_limit(limit)
if limit.is_a?(Integer) || limit.is_a?(Arel::Nodes::SqlLiteral)
limit
else
Integer(limit)
end
end 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.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 62 def select_all(arel, name = nil, binds = [], preparable: nil, async: false) arel = arel_from_relation(arel) sql, binds, preparable = to_sql_and_binds(arel, binds, preparable) select(sql, name, binds, prepare: prepared_statements && preparable, async: async && FutureResult::SelectAll) rescue ::RangeError ActiveRecord::Result.empty end
Returns an ActiveRecord::Result instance.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 73 def select_one(arel, name = nil, binds = []) select_all(arel, name, binds).first end
Returns a record hash with the column names as keys and column values as values.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 90 def select_rows(arel, name = nil, binds = []) select_all(arel, name, binds).rows end
Returns an array of arrays containing the field values. Order is the same as that returned by columns.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 78 def select_value(arel, name = nil, binds = []) single_value_from_rows(select_rows(arel, name, binds)) end
Returns a single value from a record
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 84 def select_values(arel, name = nil, binds = []) select_rows(arel, name, binds).map(&:first) end
Returns an array of the values of the first column in a select:
select_values("SELECT id FROM companies LIMIT 3") => [1,2,3] # 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
Converts an arel AST to SQL
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 309
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
else
transaction_manager.within_new_transaction(isolation: isolation, joinable: joinable, &block)
end
rescue ActiveRecord::Rollback
# rollbacks are silently swallowed
end Runs the given block in a database transaction, and returns the result of the block.
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.
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.connection.transaction do # BEGIN
Model.connection.transaction(requires_new: true) do # CREATE SAVEPOINT active_record_1
Model.connection.create_table(...)
# active_record_1 now automatically released
end # RELEASE SAVEPOINT active_record_1 <--- BOOM! database error!
end 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 and postgresql adapters support setting the transaction isolation level.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 352
def transaction_isolation_levels
{
read_uncommitted: "READ UNCOMMITTED",
read_committed: "READ COMMITTED",
repeatable_read: "REPEATABLE READ",
serializable: "SERIALIZABLE"
}
end # File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 335 def transaction_open? current_transaction.open? end
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 185 def truncate(table_name, name = nil) execute(build_truncate_statement(table_name), name) end
Executes the truncate statement.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 173 def update(arel, name = nil, binds = []) sql, binds = to_sql_and_binds(arel, binds) exec_update(sql, name, binds) end
Executes the update statement and returns the number of rows affected.
# File activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb, line 107 def write_query?(sql) raise NotImplementedError end
Determines whether the SQL statement is a write query.
© 2004–2021 David Heinemeier Hansson
Licensed under the MIT License.