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Module: ActiveRecord::ConnectionAdapters::DatabaseStatements

Constant Summary

Instance Attribute Summary

Instance Method Summary

Instance Attribute Details

#begin_transaction (readonly)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 499

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)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 499

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)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 499

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)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 499

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)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 499

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)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 499

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)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 499

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.
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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 497

attr_reader :transaction_manager # :nodoc:

#transaction_open?Boolean (readonly)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 504

def transaction_open?
  current_transaction.open?
end

#within_new_transaction (readonly)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 499

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, sequence_name = nil, returning: nil)

This method is for internal use only.
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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 208

def _exec_insert(intent, sequence_name = nil, returning: nil) # :nodoc:
  apply_returning_to!(intent, returning)
  intent.execute!
  intent.cast_result
end

#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.

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 530

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

#affected_rows(raw_result) (private)

Raises:

  • (NotImplementedError)
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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 735

def affected_rows(raw_result)
  raise NotImplementedError
end

#apply_returning_to!(intent, returning) (private)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 819

def apply_returning_to!(intent, returning)
  return unless supports_insert_returning?

  arel_or_sql = intent.arel || intent.raw_sql

  returning ||= primary_key_for_insert(arel_or_sql)
  returning = Array(returning)
  return if returning.empty?

  if arel_or_sql.is_a?(String)
    returning_statement = returning.map { |c| quote_column_name(c) }.join(", ")
    intent.raw_sql = "#{arel_or_sql} RETURNING #{returning_statement}"
  else
    arel_or_sql.returning(returning.map { |column| Arel.sql(quote_column_name(column)) })
  end
end

#arel_from_relation(relation) (private)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 867

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).

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 535

def begin_db_transaction()    end

#begin_deferred_transaction(isolation_level = nil)

This method is for internal use only.
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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 537

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.

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 560

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

#build_delete_from_statements(table_names) (private)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 809

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)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 751

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)
        with_yaml_fallback(column.cast_type.serialize(fixture[name]))
      else
        default_insert_value(column)
      end
    end
  end

  table = Arel::Table.new(name: 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)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 792

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)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 799

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

#build_truncate_statements(table_names) (private)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 803

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.

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 61

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)
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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 731

def cast_result(raw_result)
  raise NotImplementedError
end

#combine_multi_statements(total_sql) (private)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 815

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

#commit_db_transaction

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

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 574

def commit_db_transaction()   end

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

Alias for #insert.

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 299

alias create insert

#default_insert_value(column)

This method is for internal use only.
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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 658

def default_insert_value(column) # :nodoc:
  DEFAULT_INSERT_VALUE
end

#default_sequence_name(table, column)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 596

def default_sequence_name(table, column)
  nil
end

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

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

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 321

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

  intent.execute!
  intent.affected_rows
end

#disable_lazy_transactions!

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 499

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

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

#empty_insert_statement_value(primary_key = nil)

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

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

#enable_lazy_transactions!

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 499

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.

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 217

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.

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

def exec_insert(sql, name = nil, binds = [], pk = nil, sequence_name = nil, returning: nil)
  # The `pk` positional argument is really the RETURNING column name.
  # Translate it to `returning:` — including the legacy `false` sentinel
  # meaning "no primary key / skip RETURNING".
  if pk == false
    returning ||= []
  elsif pk
    returning ||= pk
  end

  intent = QueryIntent.new(adapter: self, raw_sql: sql, name: name, binds: binds)

  _exec_insert(intent, sequence_name, returning: returning)
end

#exec_insert_all(inserter, name)

This method is for internal use only.
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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 234

def exec_insert_all(inserter, name) # :nodoc:
  intent = internal_build_intent(inserter.to_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.

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 181

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.
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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 590

def exec_restart_db_transaction() end # :nodoc:

#exec_rollback_db_transaction

This method is for internal use only.
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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 584

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.

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 226

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 168

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)

This method is for internal use only.

Executes SQL statements in the context of this connection without returning a result.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 702

def execute_batch(statements, name = nil, **kwargs) # :nodoc:
  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.

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 665

def execute_intent(intent) # :nodoc:
  should_dirty = false

  if intent.materialize_transactions
    # These can raise locally (e.g., ReadOnlyError). Validate before BEGIN.
    intent.processed_sql
    intent.type_casted_binds
    materialize_transactions
  end

  log(intent) do |notification_payload|
    intent.notification_payload = notification_payload
    with_raw_connection(allow_retry: intent.allow_retry, materialize_transactions: false) do |conn|
      should_dirty = intent.materialize_transactions
      begin
        result = perform_query(conn, intent)
        intent.raw_result = result

        query_completed = true
      ensure
        begin
          handle_warnings(result, intent.processed_sql)
        rescue
          raise if query_completed

          # The query failed, so we need to swallow this exception
          # from handle_warnings to avoid masking the original.
        end
      end
    end
  end
ensure
  dirty_current_transaction if should_dirty
end

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

This method is for internal use only.

Raises:

  • (NotImplementedError)
[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 240

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

#extract_table_ref_from_insert_sql(sql) (private)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 875

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)

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# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 727

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 654

def high_precision_current_timestamp
  HIGH_PRECISION_CURRENT_TIMESTAMP
end

#initialize

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

def initialize
  super
  reset_transaction
end

#insert(arel_or_sql, 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.

Some adapters support the returning keyword argument, which controls what the method returns: nil (default) returns the id via #last_inserted_id; a column name returns that column as a single value; an array of column names returns an ::Array of column values.

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 250

def insert(arel_or_sql, name = nil, pk = nil, id_value = nil, sequence_name = nil, binds = [], returning: nil)
  unless pk.nil?
    ActiveRecord.deprecator.warn(<<~MSG.squish)
      Passing `pk` as a positional argument to `insert` is deprecated
      and will be removed in Rails 8.3. Pass `returning:` instead —
      `insert(arel, name, "id")` becomes `insert(arel, name, returning: "id")`.
    MSG
  end
  unless id_value.nil?
    ActiveRecord.deprecator.warn(<<~MSG.squish)
      Passing `id_value` as a positional argument to `insert` is
      deprecated and will be removed in Rails 8.3. `id_value` was
      returned when the database couldn't compute the last inserted id;
      callers that pass it already know the value and can use it
      directly rather than reading it back from `insert`.
    MSG
  end
  unless sequence_name.nil?
    ActiveRecord.deprecator.warn(<<~MSG.squish)
      Passing `sequence_name` as a positional argument to `insert` is
      deprecated and will be removed in Rails 8.3. It was only used by
      PostgreSQL's `use_insert_returning?` currval fallback, which is
      deprecated on its own — drop the argument once the
      `insert_returning` option is removed.
    MSG
  end

  # The `pk` positional argument is really the RETURNING column name.
  # Translate it to `returning:` — including the legacy `false` sentinel
  # meaning "no primary key / skip RETURNING".
  if pk == false
    returning ||= []
  elsif pk
    returning ||= pk
  end

  intent = QueryIntent.new(adapter: self, arel: arel_or_sql, name: name, binds: binds)

  value = _exec_insert(intent, sequence_name, returning: returning)

  case returning
  when nil
    id_value || last_inserted_id(value)
  when Array
    returning_column_values(value)
  else
    returning_column_values(value)&.first
  end
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 610

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 614

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 739

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 850

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 723

def perform_query(raw_connection, intent)
  raise NotImplementedError
end

#primary_key_for_insert(arel_or_sql) (private)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 836

def primary_key_for_insert(arel_or_sql)
  table_ref = table_ref_for_insert(arel_or_sql)
  pk = schema_cache.primary_keys(table_ref) if table_ref
  pk unless pk.is_a?(Array)
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 137

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 143

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 129

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 133

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 121

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 125

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 570

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 601

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 508

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 586

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 854

def returning_column_values(result)
  if supports_insert_returning?
    result.rows.first
  else
    [last_inserted_id(result)]
  end
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 578

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 592

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 77

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 100

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 117

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 105

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 111

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 862

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

#table_ref_for_insert(arel_or_sql) (private)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 842

def table_ref_for_insert(arel_or_sql)
  if arel_or_sql.is_a?(String)
    extract_table_ref_from_insert_sql(arel_or_sql)
  elsif arel_or_sql.respond_to?(:ast) && arel_or_sql.ast.respond_to?(:relation)
    arel_or_sql.ast.relation.name
  end
end

#to_sql(arel_or_sql, binds = nil)

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 11

def to_sql(arel_or_sql, binds = nil)
  unless binds.nil?
    ActiveRecord.deprecator.warn(<<~MSG)
      Passing `binds` to `to_sql` is deprecated and will be removed in Rails 8.3.
      The `binds` argument has been unused since bind parameters were moved into
      the Arel AST in Rails 5.2.
    MSG
  end
  sql, _ = to_sql_and_binds(arel_or_sql)
  sql
end

#to_sql_and_binds(arel_or_sql, 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 23

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

  if Arel.arel_node?(arel_or_sql) && !(String === arel_or_sql)
    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, collector)

      if binds.length > bind_params_length
        unprepared_statement do
          return to_sql_and_binds(arel_or_sql)
        end
      end
      preparable = collector.preparable
    else
      sql = visitor.compile(arel_or_sql, collector)
    end
    allow_retry = collector.retryable
    [sql.freeze, binds, preparable, allow_retry]
  else
    arel_or_sql = arel_or_sql.dup.freeze unless arel_or_sql.frozen?
    [arel_or_sql, 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: https://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 463

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 553

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 329

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 333

def truncate_tables(*table_names) # :nodoc:
  table_names -= [pool.schema_migration.table_name, pool..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_or_sql, 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 302

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

  intent.execute!
  intent.affected_rows
end

#update_with_result(arel, name = nil, returning:)

This method is for internal use only.

Executes the update statement and returns an ::ActiveRecord::Result Some adapters support the returning keyword argument

[ GitHub ]

  
# File 'activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb', line 311

def update_with_result(arel, name = nil, returning:) # :nodoc:
  arel.returning(returning.map { |column| Arel.sql(quote_column_name(column)) })

  intent = QueryIntent.new(adapter: self, arel: arel, name: name)

  intent.execute!
  intent.cast_result
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 637

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 150

def write_query?(sql)
  raise NotImplementedError
end