Faker is producing duplicate data when used in fac

问题:

I'm trying to populate some fake data into a factory using the Faker gem:

Factory.define :user do |user|
  user.first_name Faker::Name::first_name
  user.last_name Faker::Name::last_name
  user.sequence(:email) {|n| "user#{n}@blow.com" }
end

However while I expect this to produce users who have different first_name and last_names, each one is the same:

>> Factory(:user)
=> #<User id: 16, email: "[e-mail]", created_at: "2011-03-18 18:29:33",     
updated_at: "2011-03-18 18:29:33", first_name: "Bailey", last_name: "Durgan">
>> Factory(:user)
=> #<User id: 17, email: "[e-mail]", created_at: "2011-03-18 18:29:39", 
updated_at: "2011-03-18 18:29:39", first_name: "Bailey", last_name: "Durgan">

How can I get the Faker gem to generate new names for each users and not just reuse the original ones?

回答1:

Factory.define :user do |user|
  user.first_name { Faker::Name::first_name }
  user.last_name { Faker::Name::last_name }
  user.sequence(:email) {|n| "user#{n}@blow.com" }
end

Try putting brackets around the fakers. see this link

回答2:

Note that Faker may still be providing duplicate data due to the limited amount of fake data available.

For simple testing purposes and to get by uniqueness validations, I've used the following:

sequence(:first_name) {|n| Faker::Name::first_name + " (#{n})"}
sequence(:last_name) {|n| Faker::Name::last_name + " (#{n})"}

回答3:

For the sake of preserving the correct answer, here it is translocated from the blog, I take no credit for the answer.

If you use the code below, faker will not churn out unique names

Factory.define :user do |u|
  u.first_name Faker::Name.first_name
  u.last_name Faker::Name.last_name
end

However putting curly braces around faker makes it work!

Factory.define :user do |u|
  u.first_name { Faker::Name.first_name }
  u.last_name { Faker::Name.last_name }
end

To explain why, the first example is producing the same names. It's only evaluating once. The second example evaluates every time the factory is used.

This is due to the {} providing lazy evaluation. Essentially they are providing a proc/lambda with the Faker call as their return value.

回答4:

A (less efficient) alternative to using sequences when you have a uniqueness validation on an attribute is to check whether a proposed value already exists and keep trying new ones until it's unique:

FactoryGirl.define do
  factory :company do
    name do
      loop do
        possible_name = Faker::Company.name
        break possible_name unless Company.exists?(name: possible_name)
      end
    end
  end
end