Module: ActiveRecord::ConnectionAdapters::DatabaseStatements
- Included in:
- AbstractAdapter
- Defined in:
- lib/active_record/connection_adapters/abstract/database_statements.rb
Instance Attribute Summary collapse
-
#transaction_manager ⇒ Object
readonly
:nodoc:.
Instance Method Summary collapse
-
#add_transaction_record(record) ⇒ Object
Register a record with the current transaction so that its after_commit and after_rollback callbacks can be called.
-
#begin_db_transaction ⇒ Object
Begins the transaction (and turns off auto-committing).
-
#begin_isolated_db_transaction(isolation) ⇒ Object
Begins the transaction with the isolation level set.
-
#cacheable_query(klass, arel) ⇒ Object
This is used in the StatementCache object.
-
#commit_db_transaction ⇒ Object
Commits the transaction (and turns on auto-committing).
- #default_sequence_name(table, column) ⇒ Object
-
#delete(arel, name = nil, binds = []) ⇒ Object
Executes the delete statement and returns the number of rows affected.
- #empty_insert_statement_value(primary_key = nil) ⇒ Object
-
#exec_delete(sql, name = nil, binds = []) ⇒ Object
Executes delete
sql
statement in the context of this connection usingbinds
as the bind substitutes. -
#exec_insert(sql, name = nil, binds = [], pk = nil, sequence_name = nil) ⇒ Object
Executes insert
sql
statement in the context of this connection usingbinds
as the bind substitutes. -
#exec_insert_all(sql, name) ⇒ Object
:nodoc:.
-
#exec_query(sql, name = "SQL", binds = [], prepare: false) ⇒ Object
Executes
sql
statement in the context of this connection usingbinds
as the bind substitutes. -
#exec_rollback_db_transaction ⇒ Object
:nodoc:.
-
#exec_update(sql, name = nil, binds = []) ⇒ Object
Executes update
sql
statement in the context of this connection usingbinds
as the bind substitutes. -
#execute(sql, name = nil) ⇒ Object
Executes the SQL statement in the context of this connection and returns the raw result from the connection adapter.
- #initialize ⇒ Object
-
#insert(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = []) ⇒ Object
(also: #create)
Executes an INSERT query and returns the new record’s ID.
-
#insert_fixture(fixture, table_name) ⇒ Object
Inserts the given fixture into the table.
- #insert_fixtures_set(fixture_set, tables_to_delete = []) ⇒ Object
-
#query(sql, name = nil) ⇒ Object
:nodoc:.
-
#query_value(sql, name = nil) ⇒ Object
:nodoc:.
-
#query_values(sql, name = nil) ⇒ Object
:nodoc:.
-
#reset_sequence!(table, column, sequence = nil) ⇒ Object
Set the sequence to the max value of the table’s column.
-
#reset_transaction ⇒ Object
:nodoc:.
-
#rollback_db_transaction ⇒ Object
Rolls back the transaction (and turns on auto-committing).
- #rollback_to_savepoint(name = nil) ⇒ Object
-
#sanitize_limit(limit) ⇒ Object
Sanitizes the given LIMIT parameter in order to prevent SQL injection.
-
#select_all(arel, name = nil, binds = [], preparable: nil) ⇒ Object
Returns an ActiveRecord::Result instance.
-
#select_one(arel, name = nil, binds = []) ⇒ Object
Returns a record hash with the column names as keys and column values as values.
-
#select_rows(arel, name = nil, binds = []) ⇒ Object
Returns an array of arrays containing the field values.
-
#select_value(arel, name = nil, binds = []) ⇒ Object
Returns a single value from a record.
-
#select_values(arel, name = nil, binds = []) ⇒ Object
Returns an array of the values of the first column in a select: select_values(“SELECT id FROM companies LIMIT 3”) => [1,2,3].
-
#to_sql(arel_or_sql_string, binds = []) ⇒ Object
Converts an arel AST to SQL.
-
#transaction(requires_new: nil, isolation: nil, joinable: true) ⇒ Object
Runs the given block in a database transaction, and returns the result of the block.
- #transaction_isolation_levels ⇒ Object
- #transaction_open? ⇒ Boolean
- #transaction_state ⇒ Object
-
#truncate(table_name, name = nil) ⇒ Object
Executes the truncate statement.
-
#truncate_tables(*table_names) ⇒ Object
:nodoc:.
-
#update(arel, name = nil, binds = []) ⇒ Object
Executes the update statement and returns the number of rows affected.
-
#with_yaml_fallback(value) ⇒ Object
Fixture value is quoted by Arel, however scalar values are not quotable.
-
#write_query?(sql) ⇒ Boolean
Determines whether the SQL statement is a write query.
Instance Attribute Details
#transaction_manager ⇒ Object (readonly)
:nodoc:
286 287 288 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 286 def transaction_manager @transaction_manager end |
Instance Method Details
#add_transaction_record(record) ⇒ Object
Register a record with the current transaction so that its after_commit and after_rollback callbacks can be called.
302 303 304 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 302 def add_transaction_record(record) current_transaction.add_record(record) end |
#begin_db_transaction ⇒ Object
Begins the transaction (and turns off auto-committing).
311 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 311 def begin_db_transaction() end |
#begin_isolated_db_transaction(isolation) ⇒ Object
Begins the transaction with the isolation level set. Raises an error by default; adapters that support setting the isolation level should implement this method.
325 326 327 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 325 def begin_isolated_db_transaction(isolation) raise ActiveRecord::TransactionIsolationError, "adapter does not support setting transaction isolation" end |
#cacheable_query(klass, arel) ⇒ Object
This is used in the StatementCache object. It returns an object that can be used to query the database repeatedly.
46 47 48 49 50 51 52 53 54 55 56 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 46 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 |
#commit_db_transaction ⇒ Object
Commits the transaction (and turns on auto-committing).
330 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 330 def commit_db_transaction() end |
#default_sequence_name(table, column) ⇒ Object
344 345 346 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 344 def default_sequence_name(table, column) nil end |
#delete(arel, name = nil, binds = []) ⇒ Object
Executes the delete statement and returns the number of rows affected.
178 179 180 181 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 178 def delete(arel, name = nil, binds = []) sql, binds = to_sql_and_binds(arel, binds) exec_delete(sql, name, binds) end |
#empty_insert_statement_value(primary_key = nil) ⇒ Object
376 377 378 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 376 def empty_insert_statement_value(primary_key = nil) "DEFAULT VALUES" end |
#exec_delete(sql, name = nil, binds = []) ⇒ Object
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.
141 142 143 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 141 def exec_delete(sql, name = nil, binds = []) exec_query(sql, name, binds) end |
#exec_insert(sql, name = nil, binds = [], pk = nil, sequence_name = nil) ⇒ Object
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.
133 134 135 136 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 133 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 |
#exec_insert_all(sql, name) ⇒ Object
:nodoc:
152 153 154 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 152 def exec_insert_all(sql, name) # :nodoc: exec_query(sql, name) end |
#exec_query(sql, name = "SQL", binds = [], prepare: false) ⇒ Object
Executes sql
statement in the context of this connection using binds
as the bind substitutes. name
is logged along with the executed sql
statement.
126 127 128 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 126 def exec_query(sql, name = "SQL", binds = [], prepare: false) raise NotImplementedError end |
#exec_rollback_db_transaction ⇒ Object
:nodoc:
338 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 338 def exec_rollback_db_transaction() end |
#exec_update(sql, name = nil, binds = []) ⇒ Object
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.
148 149 150 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 148 def exec_update(sql, name = nil, binds = []) exec_query(sql, name, binds) end |
#execute(sql, name = nil) ⇒ Object
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.
119 120 121 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 119 def execute(sql, name = nil) raise NotImplementedError end |
#initialize ⇒ Object
6 7 8 9 |
# File '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 = []) ⇒ Object 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
.
164 165 166 167 168 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 164 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 |
#insert_fixture(fixture, table_name) ⇒ Object
Inserts the given fixture into the table. Overridden in adapters that require something beyond a simple insert (eg. 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.
358 359 360 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 358 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 = []) ⇒ Object
362 363 364 365 366 367 368 369 370 371 372 373 374 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 362 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 |
#query(sql, name = nil) ⇒ Object
:nodoc:
105 106 107 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 105 def query(sql, name = nil) # :nodoc: exec_query(sql, name).rows end |
#query_value(sql, name = nil) ⇒ Object
:nodoc:
97 98 99 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 97 def query_value(sql, name = nil) # :nodoc: single_value_from_rows(query(sql, name)) end |
#query_values(sql, name = nil) ⇒ Object
:nodoc:
101 102 103 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 101 def query_values(sql, name = nil) # :nodoc: query(sql, name).map(&:first) end |
#reset_sequence!(table, column, sequence = nil) ⇒ Object
Set the sequence to the max value of the table’s column.
349 350 351 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 349 def reset_sequence!(table, column, sequence = nil) # Do nothing by default. Implement for PostgreSQL, Oracle, ... end |
#reset_transaction ⇒ Object
:nodoc:
296 297 298 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 296 def reset_transaction #:nodoc: @transaction_manager = ConnectionAdapters::TransactionManager.new(self) end |
#rollback_db_transaction ⇒ Object
Rolls back the transaction (and turns on auto-committing). Must be done if the transaction block raises an exception or returns false.
334 335 336 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 334 def rollback_db_transaction exec_rollback_db_transaction end |
#rollback_to_savepoint(name = nil) ⇒ Object
340 341 342 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 340 def rollback_to_savepoint(name = nil) exec_rollback_to_savepoint(name) end |
#sanitize_limit(limit) ⇒ Object
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.
386 387 388 389 390 391 392 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 386 def sanitize_limit(limit) if limit.is_a?(Integer) || limit.is_a?(Arel::Nodes::SqlLiteral) limit else Integer(limit) end end |
#select_all(arel, name = nil, binds = [], preparable: nil) ⇒ Object
Returns an ActiveRecord::Result instance.
59 60 61 62 63 64 65 66 67 68 69 70 71 72 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 59 def select_all(arel, name = nil, binds = [], preparable: nil) arel = arel_from_relation(arel) sql, binds = to_sql_and_binds(arel, binds) if preparable.nil? preparable = prepared_statements ? visitor.preparable : false end if prepared_statements && preparable select_prepared(sql, name, binds) else select(sql, name, binds) end end |
#select_one(arel, name = nil, binds = []) ⇒ Object
Returns a record hash with the column names as keys and column values as values.
76 77 78 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 76 def select_one(arel, name = nil, binds = []) select_all(arel, name, binds).first end |
#select_rows(arel, name = nil, binds = []) ⇒ Object
Returns an array of arrays containing the field values. Order is the same as that returned by columns
.
93 94 95 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 93 def select_rows(arel, name = nil, binds = []) select_all(arel, name, binds).rows end |
#select_value(arel, name = nil, binds = []) ⇒ Object
Returns a single value from a record
81 82 83 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 81 def select_value(arel, name = nil, binds = []) single_value_from_rows(select_rows(arel, name, binds)) end |
#select_values(arel, name = nil, binds = []) ⇒ Object
Returns an array of the values of the first column in a select:
select_values("SELECT id FROM companies LIMIT 3") => [1,2,3]
87 88 89 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 87 def select_values(arel, name = nil, binds = []) select_rows(arel, name, binds).map(&:first) end |
#to_sql(arel_or_sql_string, binds = []) ⇒ Object
Converts an arel AST to SQL
12 13 14 15 |
# File '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 |
#transaction(requires_new: nil, isolation: nil, joinable: true) ⇒ Object
Runs the given block in a database transaction, and returns the result of the block.
Nested transactions support
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/5.7/en/savepoint.html Savepoints are supported by MySQL and PostgreSQL. SQLite3 version >= ‘3.6.8’ supports savepoints.
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.
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.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
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 and postgresql adapters support setting the transaction isolation level.
273 274 275 276 277 278 279 280 281 282 283 284 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 273 def transaction(requires_new: nil, isolation: nil, joinable: true) 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) { yield } end rescue ActiveRecord::Rollback # rollbacks are silently swallowed end |
#transaction_isolation_levels ⇒ Object
313 314 315 316 317 318 319 320 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 313 def transaction_isolation_levels { read_uncommitted: "READ UNCOMMITTED", read_committed: "READ COMMITTED", repeatable_read: "REPEATABLE READ", serializable: "SERIALIZABLE" } end |
#transaction_open? ⇒ Boolean
292 293 294 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 292 def transaction_open? current_transaction.open? end |
#transaction_state ⇒ Object
306 307 308 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 306 def transaction_state current_transaction.state end |
#truncate(table_name, name = nil) ⇒ Object
Executes the truncate statement.
184 185 186 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 184 def truncate(table_name, name = nil) execute(build_truncate_statement(table_name), name) end |
#truncate_tables(*table_names) ⇒ Object
:nodoc:
188 189 190 191 192 193 194 195 196 197 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 188 def truncate_tables(*table_names) # :nodoc: 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 = []) ⇒ Object
Executes the update statement and returns the number of rows affected.
172 173 174 175 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 172 def update(arel, name = nil, binds = []) sql, binds = to_sql_and_binds(arel, binds) exec_update(sql, name, binds) end |
#with_yaml_fallback(value) ⇒ Object
Fixture value is quoted by Arel, however scalar values are not quotable. In this case we want to convert the column value to YAML.
397 398 399 400 401 402 403 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 397 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.
110 111 112 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 110 def write_query?(sql) raise NotImplementedError end |