Rails validates_uniqueness_of除非自我验证

Question

I'm using rails for authentication and want to validate the uniqueness of a username, unless the other username was set up as a temporary account.

Example: We set up a user account that has name: "buddy" with email: "placeholder@email.com"

A user comes and creates an account. We want the user to be able to user the name "buddy" if the only other buddy account is associated with email: "placehoder@gmail.com".

Bascially I want to do something along the lines of:

validates_uniqueness_of :name, unless: User.where(name: :name).first.email.include?("placeholder@email.com")

What is the correct way to do this?

Answer 1

您可以将Proc传递给exclude：选项，就像这样...

validates_uniqueness_of :name, unless: Proc.new { |user| User.where(name: user.name).first && User.where(name: user.name.first.email.include?(user.email) }

Answer 2

validates_uniqueness_of :name, conditions: -> {where.not(email: "placeholder@email.com")}

This will generate a query like

SELECT 1 AS one FROM "users"
  WHERE ("users"."name" = 'buddy') AND
        ("users"."email" != 'placeholder@email.com')
  LIMIT 1