Module: ActiveRecord::ConnectionAdapters::DatabaseStatements
- Included in:
- AbstractAdapter
- Defined in:
- lib/active_record/connection_adapters/abstract/database_statements.rb
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.
-
#begin_transaction(options = {}) ⇒ Object
:nodoc:.
-
#commit_db_transaction ⇒ Object
Commits the transaction (and turns on auto-committing).
-
#commit_transaction ⇒ Object
:nodoc:.
-
#current_transaction ⇒ Object
:nodoc:.
- #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 ⇒ Object
-
#exec_delete(sql, name, binds) ⇒ Object
Executes delete
sql
statement in the context of this connection usingbinds
as the bind substitutes. -
#exec_insert(sql, name, binds, pk = nil, sequence_name = nil) ⇒ Object
Executes insert
sql
statement in the context of this connection usingbinds
as the bind substitutes. -
#exec_query(sql, name = 'SQL', binds = []) ⇒ Object
Executes
sql
statement in the context of this connection usingbinds
as the bind substitutes. -
#exec_update(sql, name, 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.
- #initialize ⇒ Object
-
#insert(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = []) ⇒ Object
Returns the last auto-generated ID from the affected table.
-
#insert_fixture(fixture, table_name) ⇒ Object
Inserts the given fixture into the table.
-
#join_to_delete(delete, select, key) ⇒ Object
:nodoc:.
-
#join_to_update(update, select) ⇒ Object
The default strategy for an UPDATE with joins is to use a subquery.
- #limited_update_conditions(where_sql, quoted_table_name, quoted_primary_key) ⇒ Object
-
#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_transaction ⇒ Object
:nodoc:.
-
#sanitize_limit(limit) ⇒ Object
Sanitizes the given LIMIT parameter in order to prevent SQL injection.
-
#select_all(arel, name = nil, binds = []) ⇒ 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(sql, 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) ⇒ 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].
-
#supports_statement_cache? ⇒ Boolean
Returns
true
when the connection adapter supports prepared statement caching, otherwise returnsfalse
. -
#to_sql(arel, binds = []) ⇒ Object
Converts an arel AST to SQL.
-
#transaction(options = {}) ⇒ Object
Runs the given block in a database transaction, and returns the result of the block.
- #transaction_isolation_levels ⇒ Object
- #transaction_open? ⇒ Boolean
-
#update(arel, name = nil, binds = []) ⇒ Object
Executes the update statement and returns the number of rows affected.
-
#within_new_transaction(options = {}) ⇒ Object
:nodoc:.
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.
258 259 260 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 258 def add_transaction_record(record) @transaction.add_record(record) end |
#begin_db_transaction ⇒ Object
Begins the transaction (and turns off auto-committing).
263 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 263 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.
277 278 279 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 277 def begin_isolated_db_transaction(isolation) raise ActiveRecord::TransactionIsolationError, "adapter does not support setting transaction isolation" end |
#begin_transaction(options = {}) ⇒ Object
:nodoc:
240 241 242 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 240 def begin_transaction( = {}) #:nodoc: @transaction = @transaction.begin() end |
#commit_db_transaction ⇒ Object
Commits the transaction (and turns on auto-committing).
282 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 282 def commit_db_transaction() end |
#commit_transaction ⇒ Object
:nodoc:
244 245 246 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 244 def commit_transaction #:nodoc: @transaction = @transaction.commit end |
#current_transaction ⇒ Object
:nodoc:
232 233 234 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 232 def current_transaction #:nodoc: @transaction end |
#default_sequence_name(table, column) ⇒ Object
288 289 290 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 288 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.
115 116 117 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 115 def delete(arel, name = nil, binds = []) exec_delete(to_sql(arel, binds), name, binds) end |
#empty_insert_statement_value ⇒ Object
311 312 313 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 311 def empty_insert_statement_value "DEFAULT VALUES" end |
#exec_delete(sql, name, 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.
84 85 86 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 84 def exec_delete(sql, name, binds) exec_query(sql, name, binds) end |
#exec_insert(sql, name, 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.
77 78 79 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 77 def exec_insert(sql, name, binds, pk = nil, sequence_name = nil) exec_query(sql, name, binds) end |
#exec_query(sql, name = 'SQL', binds = []) ⇒ 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.
71 72 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 71 def exec_query(sql, name = 'SQL', binds = []) end |
#exec_update(sql, name, 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.
91 92 93 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 91 def exec_update(sql, name, binds) exec_query(sql, name, binds) end |
#execute(sql, name = nil) ⇒ Object
Executes the SQL statement in the context of this connection.
64 65 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 64 def execute(sql, name = nil) end |
#initialize ⇒ Object
4 5 6 7 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 4 def initialize super reset_transaction end |
#insert(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = []) ⇒ Object
Returns the last auto-generated ID from the affected table.
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
.
103 104 105 106 107 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 103 def insert(arel, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = []) sql, binds = sql_for_insert(to_sql(arel, binds), pk, id_value, sequence_name, 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).
299 300 301 302 303 304 305 306 307 308 309 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 299 def insert_fixture(fixture, table_name) columns = schema_cache.columns_hash(table_name) key_list = [] value_list = fixture.map do |name, value| key_list << quote_column_name(name) quote(value, columns[name]) end execute "INSERT INTO #{quote_table_name(table_name)} (#{key_list.join(', ')}) VALUES (#{value_list.join(', ')})", 'Fixture Insert' end |
#join_to_delete(delete, select, key) ⇒ Object
:nodoc:
348 349 350 351 352 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 348 def join_to_delete(delete, select, key) #:nodoc: subselect = subquery_for(key, select) delete.where key.in(subselect) end |
#join_to_update(update, select) ⇒ Object
The default strategy for an UPDATE with joins is to use a subquery. This doesn’t work on mysql (even when aliasing the tables), but mysql allows using JOIN directly in an UPDATE statement, so in the mysql adapters we redefine this to do that.
341 342 343 344 345 346 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 341 def join_to_update(update, select) #:nodoc: key = update.key subselect = subquery_for(key, select) update.where key.in(subselect) end |
#limited_update_conditions(where_sql, quoted_table_name, quoted_primary_key) ⇒ Object
315 316 317 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 315 def limited_update_conditions(where_sql, quoted_table_name, quoted_primary_key) "WHERE #{quoted_primary_key} IN (SELECT #{quoted_primary_key} FROM #{quoted_table_name} #{where_sql})" end |
#reset_sequence!(table, column, sequence = nil) ⇒ Object
Set the sequence to the max value of the table’s column.
293 294 295 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 293 def reset_sequence!(table, column, sequence = nil) # Do nothing by default. Implement for PostgreSQL, Oracle, ... end |
#reset_transaction ⇒ Object
:nodoc:
252 253 254 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 252 def reset_transaction #:nodoc: @transaction = ClosedTransaction.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.
286 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 286 def rollback_db_transaction() end |
#rollback_transaction ⇒ Object
:nodoc:
248 249 250 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 248 def rollback_transaction #:nodoc: @transaction = @transaction.rollback 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 a comma-delimited list of integers, or an Arel SQL literal.
Returns Integer and Arel::Nodes::SqlLiteral limits as is. Returns the sanitized limit parameter, either as an integer, or as a string which contains a comma-delimited list of integers.
328 329 330 331 332 333 334 335 336 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 328 def sanitize_limit(limit) if limit.is_a?(Integer) || limit.is_a?(Arel::Nodes::SqlLiteral) limit elsif limit.to_s =~ /,/ Arel.sql limit.to_s.split(',').map{ |i| Integer(i) }.join(',') else Integer(limit) end end |
#select_all(arel, name = nil, binds = []) ⇒ Object
Returns an ActiveRecord::Result instance.
22 23 24 25 26 27 28 29 30 31 32 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 22 def select_all(arel, name = nil, binds = []) if arel.is_a?(Relation) relation = arel arel = relation.arel if !binds || binds.empty? binds = relation.bind_values end end select(to_sql(arel, binds), name, binds) end |
#select_one(arel, name = nil, binds = []) ⇒ Object
Returns a record hash with the column names as keys and column values as values.
36 37 38 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 36 def select_one(arel, name = nil, binds = []) select_all(arel, name, binds).first end |
#select_rows(sql, name = nil, binds = []) ⇒ Object
Returns an array of arrays containing the field values. Order is the same as that returned by columns
.
59 60 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 59 def select_rows(sql, name = nil, binds = []) end |
#select_value(arel, name = nil, binds = []) ⇒ Object
Returns a single value from a record
41 42 43 44 45 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 41 def select_value(arel, name = nil, binds = []) if result = select_one(arel, name, binds) result.values.first end end |
#select_values(arel, name = nil) ⇒ 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]
49 50 51 52 53 54 55 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 49 def select_values(arel, name = nil) binds = [] if arel.is_a?(Relation) arel, binds = arel.arel, arel.bind_values end select_rows(to_sql(arel, binds), name, binds).map(&:first) end |
#supports_statement_cache? ⇒ Boolean
Returns true
when the connection adapter supports prepared statement caching, otherwise returns false
121 122 123 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 121 def supports_statement_cache? false end |
#to_sql(arel, binds = []) ⇒ Object
Converts an arel AST to SQL
10 11 12 13 14 15 16 17 18 19 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 10 def to_sql(arel, binds = []) if arel.respond_to?(:ast) binds = binds.dup visitor.accept(arel.ast) do quote(*binds.shift.reverse) end else arel end end |
#transaction(options = {}) ⇒ 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/5.0/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 mysql, mysql2 and postgresql adapters support setting the transaction isolation level. However, support is disabled for mysql versions below 5, because they are affected by a bug which means the isolation level gets persisted outside the transaction.
201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 201 def transaction( = {}) .assert_valid_keys :requires_new, :joinable, :isolation if ![:requires_new] && current_transaction.joinable? if [:isolation] raise ActiveRecord::TransactionIsolationError, "cannot set isolation when joining a transaction" end yield else within_new_transaction() { yield } end rescue ActiveRecord::Rollback # rollbacks are silently swallowed end |
#transaction_isolation_levels ⇒ Object
265 266 267 268 269 270 271 272 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 265 def transaction_isolation_levels { read_uncommitted: "READ UNCOMMITTED", read_committed: "READ COMMITTED", repeatable_read: "REPEATABLE READ", serializable: "SERIALIZABLE" } end |
#transaction_open? ⇒ Boolean
236 237 238 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 236 def transaction_open? @transaction.open? end |
#update(arel, name = nil, binds = []) ⇒ Object
Executes the update statement and returns the number of rows affected.
110 111 112 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 110 def update(arel, name = nil, binds = []) exec_update(to_sql(arel, binds), name, binds) end |
#within_new_transaction(options = {}) ⇒ Object
:nodoc:
217 218 219 220 221 222 223 224 225 226 227 228 229 230 |
# File 'lib/active_record/connection_adapters/abstract/database_statements.rb', line 217 def within_new_transaction( = {}) #:nodoc: transaction = begin_transaction() yield rescue Exception => error rollback_transaction if transaction raise ensure begin commit_transaction unless error rescue Exception rollback_transaction raise end end |