使用FactoryGirl时association_id为nil的问题求助

Let's break down what's going wrong here and get your associations working correctly.

The Core Problem #

You're passing foreign key field names (entity_id, social_media_site_id) to the association method, but FactoryGirl expects the association name defined in your model instead. When you use the field name directly, FactoryGirl can't properly create the associated record and populate the foreign key—hence the nil values.

Step 1: Confirm Your Model Associations #

First, let's clarify what your AccountInfo model's association looks like, since you mentioned it "belongs to Person" and have an entity_type field (this hints at either a custom foreign key or a polymorphic association):

Scenario 1: Custom Foreign Key (Non-Polymorphic)

If your model uses a custom foreign key for the Person association:

# app/models/account_info.rb
class AccountInfo < ApplicationRecord
  belongs_to :person, foreign_key: :entity_id
  belongs_to :social_media_site, foreign_key: :social_media_site_id
end

Scenario 2: Polymorphic Association

If entity is a polymorphic association (since you have entity_type):

# app/models/account_info.rb
class AccountInfo < ApplicationRecord
  belongs_to :entity, polymorphic: true
  belongs_to :social_media_site
end

Step 2: Fix the Factory Definition #

Adjust your factory to use the correct association names instead of the foreign key fields:

For Scenario 1 (Custom Foreign Key):

FactoryGirl.define do
  factory :account_info do
    entity_type 1 # Keep this if it's a required field for your logic
    account_key { Faker::Twitter.user[:id] }
    
    # Use the association name :person, FactoryGirl auto-sets entity_id
    association :person, factory: :person
    # Use :social_media_site instead of social_media_site_id
    association :social_media_site, factory: :twitter
  end
end

For Scenario 2 (Polymorphic Association):

FactoryGirl.define do
  factory :account_info do
    # FactoryGirl will auto-set entity_type when you associate :entity with a Person
    # entity_type 'Person' # Uncomment if you need to hardcode it instead of auto-set
    account_key { Faker::Twitter.user[:id] }
    
    # Associate the polymorphic :entity with the :person factory
    association :entity, factory: :person
    association :social_media_site, factory: :twitter
  end
end

Why This Works #

When you pass the association name (like :person or :entity) to association, FactoryGirl:

1. Creates an instance of the associated model using the specified factory
2. Automatically assigns the correct foreign key (e.g., entity_id for the :person association) on your AccountInfo record

Bonus: Overriding Associated Attributes #

If you need to customize the associated record's attributes, you can use a block:

association :entity, factory: :person do
  first_name "Lucian"
  last_name "Tarna"
end

内容的提问来源于stack exchange，提问作者Lucian Tarna