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Suppose the following DB migration in Ruby:
create_table :question_votes do |t| t.integer :user_id t.integer :question_id t.integer :vote t.timestamps end
Suppose further that I wish the rows in the DB contain unique (user_id, question_id) pairs. What is the right dust to put in the model to accomplish that?
validates_uniqueness_of :user_id, :question_idseems to simply make rows unique by user id, and unique by question id, instead of unique by the pair.
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Validations are used to ensure that only valid data is saved into your database. For example, it may be important to your application to ensure that every user provides a valid email address and mailing address. Model-level validations are the best way to ensure that only valid data is saved into your database.
Rails validation defines valid states for each of your Active Record model classes. They are used to ensure that only valid details are entered into your database. Rails make it easy to add validations to your model classes and allows you to create your own validation methods as well.
Published Feb 02, 2018. Validation is one of the core features which rails provides. There are plenty of built in validation helpers there which helps validating our form inputs or user attributes.
validates_uniqueness_of :user_id, :scope => [:question_id] if you needed to include another column (or more), you can add that to the scope as well. Example:
validates_uniqueness_of :user_id, :scope => [:question_id, :some_third_column] If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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