问题
I have a User model that belongs to a Group. Group must have unique name attribute. User factory and group factory are defined as:
Factory.define :user do |f|
f.association :group, :factory => :group
# ...
end
Factory.define :group do |f|
f.name "default"
end
When the first user is created a new group is created too. When I try to create a second user it fails because it wants to create same group again.
Is there a way to tell factory_girl association method to look first for an existing record?
Note: I did try to define a method to handle this, but then I cannot use f.association. I would like to be able to use it in Cucumber scenarios like this:
Given the following user exists:
| Email | Group |
| test@email.com | Name: mygroup |
and this can only work if association is used in Factory definition.
回答1:
You can to use initialize_with with find_or_create method
FactoryGirl.define do
factory :group do
name "name"
initialize_with { Group.find_or_create_by_name(name)}
end
factory :user do
association :group
end
end
It can also be used with id
FactoryGirl.define do
factory :group do
id 1
attr_1 "default"
attr_2 "default"
...
attr_n "default"
initialize_with { Group.find_or_create_by_id(id)}
end
factory :user do
association :group
end
end
For Rails 4
The correct way in Rails 4 is Group.find_or_create_by(name: name), so you'd use
initialize_with { Group.find_or_create_by(name: name) }
instead.
回答2:
I ended up using a mix of methods found around the net, one of them being inherited factories as suggested by duckyfuzz in another answer.
I did following:
# in groups.rb factory
def get_group_named(name)
# get existing group or create new one
Group.where(:name => name).first || Factory(:group, :name => name)
end
Factory.define :group do |f|
f.name "default"
end
# in users.rb factory
Factory.define :user_in_whatever do |f|
f.group { |user| get_group_named("whatever") }
end
回答3:
You can also use a FactoryGirl strategy to achieve this
module FactoryGirl
module Strategy
class Find
def association(runner)
runner.run
end
def result(evaluation)
build_class(evaluation).where(get_overrides(evaluation)).first
end
private
def build_class(evaluation)
evaluation.instance_variable_get(:@attribute_assigner).instance_variable_get(:@build_class)
end
def get_overrides(evaluation = nil)
return @overrides unless @overrides.nil?
evaluation.instance_variable_get(:@attribute_assigner).instance_variable_get(:@evaluator).instance_variable_get(:@overrides).clone
end
end
class FindOrCreate
def initialize
@strategy = FactoryGirl.strategy_by_name(:find).new
end
delegate :association, to: :@strategy
def result(evaluation)
found_object = @strategy.result(evaluation)
if found_object.nil?
@strategy = FactoryGirl.strategy_by_name(:create).new
@strategy.result(evaluation)
else
found_object
end
end
end
end
register_strategy(:find, Strategy::Find)
register_strategy(:find_or_create, Strategy::FindOrCreate)
end
You can use this gist. And then do the following
FactoryGirl.define do
factory :group do
name "name"
end
factory :user do
association :group, factory: :group, strategy: :find_or_create, name: "name"
end
end
This is working for me, though.
回答4:
Usually I just make multiple factory definitions. One for a user with a group and one for a groupless user:
Factory.define :user do |u|
u.email "email"
# other attributes
end
Factory.define :grouped_user, :parent => :user do |u|
u.association :group
# this will inherit the attributes of :user
end
THen you can use these in your step definitions to create users and groups seperatly and join them together at will. For example you could create one grouped user and one lone user and join the lone user to the grouped users team.
Anyway, you should take a look at the pickle gem which will allow you to write steps like:
Given a user exists with email: "hello@email.com"
And a group exists with name: "default"
And the user: "hello@gmail.com" has joined that group
When somethings happens....
回答5:
I'm using exactly the Cucumber scenario you described in your question:
Given the following user exists:
| Email | Group |
| test@email.com | Name: mygroup |
You can extend it like:
Given the following user exists:
| Email | Group |
| test@email.com | Name: mygroup |
| foo@email.com | Name: mygroup |
| bar@email.com | Name: mygroup |
This will create 3 users with the group "mygroup". As it used like this uses 'find_or_create_by' functionality, the first call creates the group, the next two calls finds the already created group.
回答6:
I faced a similar issue lately, and here's what I tried.
To ensure FactoryBot's build and create still behaves as it should, we should only override the logic of create, by doing:
factory :user do
association :group, factory: :group
# ...
end
factory :group do
to_create do |instance|
instance.attributes = Group.find_or_create_by(name: instance.name).attributes
instance.reload
end
name { "default" }
end
This ensures build maintains it's default behavior of "building/initializing the object" and does not perform any database read or write so it's always fast. Only logic of create is overridden to fetch an existing record if exists, instead of attempting to always create a new record.
I wrote an article explaining this.
回答7:
I had a similar problem and came up with this solution. It looks for a group by name and if it is found it associates the user with that group. Otherwise it creates a group by that name and then associates with it.
factory :user do
group { Group.find_by(name: 'unique_name') || FactoryBot.create(:group, name: 'unique_name') }
end
I hope this can be useful to someone :)
来源：https://stackoverflow.com/questions/7145256/find-or-create-record-through-factory-girl-association