Is validates_uniqueness_of transaction safe?

rubyonrails-talk
1

Hi All,

I've recently starting programming in RoR. Here's a question re: the ActiveRecord validation methods. Are they transaction safe?

It seems that saving an instance of a model with validation methods could require multiple db queries. For example, validated_uniqueness_of would need to do at least one query to figure out if the value already exists and then the second query to insert a new record.

Are these queries contained in a single transaction? If not, how do you make sure that they are part of the same transaction?

Thanks for your help!

2

dparkmit wrote:

I've recently starting programming in RoR. Here's a question re: the ActiveRecord validation methods. Are they transaction safe?

It seems that saving an instance of a model with validation methods could require multiple db queries. For example, validated_uniqueness_of would need to do at least one query to figure out if the value already exists and then the second query to insert a new record.

Are these queries contained in a single transaction? If not, how do you make sure that they are part of the same transaction?

Yes validates_uniqueness_of may fail when there concurrent validations because it doesn't lock the table. To be sure you'd have to either lock the table in a before_validation callback or add a unique index to the table and handle the error.