¿Cómo puedo hacer que Ruby on Rails maneje errores de registro duplicados de MySQL?

Question

Tengo un índice único en múltiples campos en mi base de datos. Por lo tanto, si intentas guardar en un registro duplicado, activa ActiveRecord :: StatementInvalid y muestra el error mysql. ¿Hay alguna manera de manejar esto dentro de los rieles creando la restricción única o haciendo que devuelva un mensaje de error relevante cuando esto sucede?

heres la traza:

ActiveRecord::StatementInvalid: Mysql::Error: Duplicate entry '2010-12-09-2-0-1-1' for key 2: INSERT INTO `entries` (`rejected_at`, `created_at`, `comments`, `overtime`, `submitted_at`, `updated_at`, `time`, `approved`, `day`, `user_id`, `approved_at`, `job_id`, `submitted`, `rejected`) VALUES(NULL, '2010-12-09 21:50:46', NULL, 0, NULL, '2010-12-09 21:50:46', 2.0, NULL, '2010-12-09', 1, NULL, 1, NULL, NULL) 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb:219:in `log' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb:319:in `execute' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:259:in `insert_sql' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb:329:in `insert_sql' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:44:in `insert_without_query_dirty' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb:18:in `insert' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/base.rb:2901:in `create_without_timestamps' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/timestamp.rb:53:in `create_without_callbacks' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/callbacks.rb:266:in `create' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/base.rb:2867:in `create_or_update_without_callbacks' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/callbacks.rb:250:in `create_or_update' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/base.rb:2538:in `save_without_validation' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/validations.rb:1078:in `save_without_dirty' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/dirty.rb:79:in `save_without_transactions' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/transactions.rb:229:in `send' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/transactions.rb:229:in `with_transaction_returning_status' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb:136:in `transaction' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/transactions.rb:182:in `transaction' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/transactions.rb:228:in `with_transaction_returning_status' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/transactions.rb:196:in `save' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/transactions.rb:208:in `rollback_active_record_state!' 
from /home/cmatthews/src/cannon/vendor/rails/activerecord/lib/active_record/transactions.rb:196:in `save' 

Answer 1

Puede agregar una restricción de exclusividad a su modelo para que el registro regrese con errores y no sea válido.

Por ejemplo (carriles 2):

class User < ActiveRecord::Base 
    validates_uniqueness_of :email, :scope => [:name, :age] 
end 

o (carriles 3)

class User < ActiveRecord::Base 
    validates :email, :uniqueness => {:scope => [:name, :age]} 
end 

Esto debe resultar en lo siguiente:

user1 = User.create :email => "one@example.com", :name => "one", :age => 20 
user2 = User.create :email => "one@example.com", :name => "one", :age => 20 
user2.valid? # false 

Answer 2

¿Puede cambiar la consulta a

INSERT IGNORE INTO `entries` ... 

Alternativamente, usted podría considerar INSERT... ON DUPLICATE KEY UPDATE....

La documentación INSERT es here.

Answer 3

begin 
    Event.create!(:name => 'Ironman Lanzarote 2011') 
rescue ActiveRecord::RecordNotUnique => e 
    # handle duplicate entry 
end 

Esto funciona para yo bajo Rails 3.