CODEWITHSUNDEEP
mysqlruby-on-railsruby-on-rails-4activerecordrails-migrations
svelandiag
svelandiag

Reputation: 4320

Rails: Adding unique index with migration throws Mysql2::Error: BLOB/TEXT

I have this models:

ofert.rb

class Ofert < ActiveRecord::Base
belongs_to :user
validates_uniqueness_of :reference, scope: :user_id
end

user.rb

class User < ActiveRecord::Base
    has_many :oferts
end

I want to validate the uniqueness of the attribute reference scoped by user_id, I mean, the same user can't have a product with the same reference, but the reference can be repeated if it's not the same user.

as you can see there is a validates_uniqueness_of statement in the Ofert model, then I added this migration:

add_index(:oferts, [:reference, :user_id], unique: true)

However when I run the migration I get the following error:

Mysql2::Error: BLOB/TEXT column 'reference' used in key specification without a key length: CREATE UNIQUE INDEX `index_oferts_on_reference_and_user_id`  ON `oferts` (`reference`, `user_id`)

What's wrong here?

Upvotes: 1

Views: 435

Answers (1)

infused
infused

Reputation: 24337

Since :reference is a text or blob column, you must specify a length for the index:

add_index :oferts, [:reference, :user_id], unique: true, length: 10

There are maximum length limits that depend on the database engine you are using, so double check the MySQL index documentation.

Upvotes: 2

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