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Rails Transaction Demonstration
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| require 'spec_helper' | |
| describe 'Rails Transaction Demonstration' do | |
| it 'Should rollback due to any exception raised' do | |
| expect { | |
| ActiveRecord::Base.transaction do | |
| NotificationHistory.create!(transporter: 'should not see this') | |
| Resource.create(name: 'should not see this') | |
| NotificationHistory.first.transporter = 'should not see this' | |
| NotificationHistory.first.save! | |
| raise 'should not have create / saves persisting' | |
| end | |
| }.to raise_error | |
| NotificationHistory.count.should == 0 | |
| Resource.count.should == 0 | |
| end | |
| context 'Special case of ActiveRecord::Rollback exception' do | |
| it 'Creates objects even though Rollback is triggered in inner txn' do | |
| # this is created | |
| NotificationHistory.create!(transporter: 'first') | |
| expect { | |
| ActiveRecord::Base.transaction do | |
| # this is created, inner transaction rollback doesnt affect at all | |
| NotificationHistory.create!(transporter: 'This is created') | |
| ActiveRecord::Base.transaction do | |
| # this is created, inner transaction rollback doesnt affect at all | |
| NotificationHistory.create!(transporter: 'Inner transporter') | |
| raise ActiveRecord::Rollback | |
| end | |
| end | |
| }.to_not raise_error | |
| # 3 Objects created, 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. | |
| NotificationHistory.count.should == 3 | |
| end | |
| it 'Creates only parent objects when RollBack is triggered in inner txn' do | |
| # this is created | |
| NotificationHistory.create!(transporter: 'first') | |
| expect { | |
| ActiveRecord::Base.transaction do | |
| # this is created, inner transaction rollback doesnt affect parent | |
| NotificationHistory.create!(transporter: 'This is created') | |
| ActiveRecord::Base.transaction(requires_new: true) do | |
| # not created! | |
| NotificationHistory.create!(transporter: 'Inner transporter') | |
| raise ActiveRecord::Rollback | |
| end | |
| end | |
| }.to_not raise_error | |
| # only 2 objects created. 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. | |
| NotificationHistory.count.should == 2 | |
| NotificationHistory.first.transporter.should == 'first' | |
| end | |
| end | |
| end |
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