Class: SqlPostgres::Transaction

Inherits:
Object
  • Object
show all
Defined in:
lib/sqlpostgres/Transaction.rb

Overview

This class handles an SQL transaction.

Example: ** example: transaction

Transaction.new(connection) do

  insert = Insert.new('foo', connection)
  insert.insert('i', 1)
  insert.exec

  insert = Insert.new('foo', connection)
  insert.insert('i', 2)
  insert.exec

end

**

Instance Method Summary collapse

Constructor Details

#initialize(connection = Connection.default) ⇒ Transaction

Create an SQL transaction, yield, and then end the transaction. If an exception occurs, the transaction is aborted.

If no connection is given, then the default connection is used.



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# File 'lib/sqlpostgres/Transaction.rb', line 27

def initialize(connection = Connection.default)
  @state = :open
  @finished = false
  @connection = connection
  @connection.exec("begin transaction")
  begin
    result = yield(self)
    commit
    result
  rescue Exception
    abort
    raise
  end
end

Instance Method Details

#abort ⇒ Object

Abort this transaction. This is done for you when an exception occurs within the block you passed to “new”. Call this when you want to abort a transaction without throwing an exception.

Example:

** example: transaction_abort

Transaction.new(connection) do |transaction|
  insert = Insert.new('foo', connection)
  insert.insert('i', 1)
  insert.exec
  transaction.abort
end

select = Select.new(connection)
select.select('i')
select.from('foo')
p select.exec            # []

**



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# File 'lib/sqlpostgres/Transaction.rb', line 94

def abort
  unless @finished
    do_abort
  end
end

#commit ⇒ Object

Commit this transaction. This is done for you unless an exception occurs within the block you passed to “new”. Call this when you want to commit the transaction before raising an exception – in other words, when you want to keep your database changes even though an exception is about to occur.

Example:

** example: transaction_commit 

begin
  Transaction.new(connection) do |transaction|
    insert = Insert.new('foo', connection)
    insert.insert('i', 1)
    insert.exec
    transaction.commit
    raise
  end
rescue Exception => e
end

select = Select.new(connection)
select.select('i')
select.from('foo')
p select.exec            # [{"i"=>1}]

**



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# File 'lib/sqlpostgres/Transaction.rb', line 68

def commit
  unless @finished
    do_commit
  end
end