How to handle database errors in Rails?

Question

I have that in my migration for table

t.string :name, :null => false

When user trying to save model with null name then it gives an error. How can I handle it and give back beautiful message? I don't wanna use validates

validates :name, presence: true

Answer 1

You can try Migrations Validators project ( https://github.com/vprokopchuk256/mv-core ). It allows you to define validations on a database level.

Example:

def change
  create_table :items do |t|
    t.string :name, presence: true
  end
end

And you can define event beautiful message:

def change
  create_table :items do |t|
    t.string :name, presence: {message: 'not beautiful', as: :trigger}
  end
end

In this case validation would be defined as condition inside trigger. You can define that trigger name or trigger event. Just see documentation to the project. In case validation is failed then db exception with specified message is risen.

And if you want to handle error from that constraint graciously you can do it in this way:

class Item < ActiveRecord::Base
  enforce_migration_validations
end

As result:

Item.new(name: nil).valid?
=> false

Item.new(name: 'Mr. Smith').valid?
=> true