In my Game model, I have
class Game < ApplicationRecord
has_many :assignments
has_many :users, through: :assignments
accepts_nested_attributes_for :assignments
after_create :create_assignments
def create_assignments
3.times { Assignment.create!(game_id: id, user_id: 1) }
end
end
This works but I need the user_id to be blank when it's created (it will be edited at a later time). It won't create assignments unless there is a user_id with a value.
I've tried leaving it blank and omitting it, but that doesn't work. I think I need to put optional: true somewhere but I'm pretty stumped on this one.
Needed to add :optional => true on Assignment Model
class Assignment < ApplicationRecord
belongs_to :game
belongs_to :user, :optional => true
end
Related
There are models: member(id,project_id,user_id), project(id), user(id), somemodel(id, project_id, user_id).
member belongs_to :project, belongs_to :user
somemodel belongs_to :project, belongs_to :user
I would like that when a member is deleted so somemodel (that has project_id and user_id the same as that member) is deleted also. How to do that?
To do that I would like has_many :somemodels, dependent: :destroy to be added to member , but I don't know the right parameters to give to has_many :somemodels in member class. has_many :somemodels, dependent: :destroy alone doesn't work as it tries to search for somemodel by member_id which is not present on the somemodels table and so the no column error occurs.
What would be the right has_many :somemodels ... to be added to Member?
An alternative way could be to create a :through association for this specific relation, and then set that one to dependent: :destroy. I think it would be structured like this:
class Member < ActiveRecord::Base
belongs_to :user
belongs_to :project
has_many :some_models, ->(member) { where(user_id: member.user_id) },
through: :project,
dependent: :destroy
end
I haven't tested it, but it seems right as far as I can see.
I think you should add a after_destroy callback to Member model:
# In member model
class Member < ApplicationRecord
after_destroy :also_destroy_somemodel
...
def also_destroy_somemodel
# Fast, use in case somemodel dont have any callbacks
Somemodel.where(project_id: project_id, user_id: user_id).delete_all
# Or
# Slow, use in case somemodel has callback(s)
# Somemodel.where(project_id: project_id, user_id: user_id).each &:destroy
end
end
Hope it helps.
i have three models, all for a has_many :through relationship. They look like this:
class Company < ActiveRecord::Base
has_many :company_users, dependent: :destroy
has_many :users, through: :company_users
accepts_nested_attributes_for :company_users, :users
end
class CompanyUser < ActiveRecord::Base
self.table_name = :companies_users #this is because this was originally a habtm relationship
belongs_to :company
belongs_to :user
end
class User < ActiveRecord::Base
# this is a devise model, if that matters
has_many :company_users, dependent: :destroy
has_many :companies, through: :company_users
accepts_nested_attributes_for :company_users, :companies
end
this loads fine, and the joins are built fine for queries. However, whenever i do something like
#company = Company.last
#user = #company.users.build(params[:user])
#user.save #=> true
#company.save #=> true
both the User record and the CompanyUser records get created, but the company_id field in the CompanyUser record is set to NULL
INSERT INTO `companies_users` (`company_id`, `created_at`,`updated_at`, `user_id`)
VALUES (NULL, '2012-02-19 02:09:04', '2012-02-19 02:09:04', 18)
it does the same thing when you #company.users << #user
I'm sure that I'm doing something stupid here, I just don't know what.
You can't use a has_many :through like that, you have to do it like this:
#company = Company.last
#user = User.create( params[:user] )
#company.company_users.create( :user_id => #user.id )
Then you will have the association defined correctly.
update
In the case of the comment below, as you already have accepts_nested_attributes_for, your parameters would have to come like this:
{ :company =>
{ :company_users_attributes =>
[
{ :company_id => 1, :user_id => 1 } ,
{ :company_id => 1, :user_id => 2 },
{ :company_id => 1, :user_id => 3 }
]
}
}
And you would have users being added to companies automatically for you.
If you have a has_many :through association and you want to save an association using build you can accomplish this using the :inverse_of option on the belongs_to association in the Join Model
Here's a modified example from the rails docs where tags has a has_many :through association with posts and the developer is attempting to save tags through the join model (PostTag) using the build method:
#post = Post.first
#tag = #post.tags.build name: "ruby"
#tag.save
The common expectation is that the last line should save the "through" record in the join table (post_tags). However, this will not work by default. This will only work if the :inverse_of is set:
class PostTag < ActiveRecord::Base
belongs_to :post
belongs_to :tag, inverse_of: :post_tags # add inverse_of option
end
class Post < ActiveRecord::Base
has_many :post_tags
has_many :tags, through: :post_tags
end
class Tag < ActiveRecord::Base
has_many :post_tags
has_many :posts, through: :post_tags
end
So for the question above, setting the :inverse_of option on the belongs_to :user association in the Join Model (CompanyUser) like this:
class CompanyUser < ActiveRecord::Base
belongs_to :company
belongs_to :user, inverse_of: :company_users
end
will result in the following code correctly creating a record in the join table (company_users)
company = Company.first
company.users.build(name: "James")
company.save
Source: here & here
I suspect your params[:user] parameter, otherwise your code seems clean. We can use build method with 1..n and n..n associations too, see here.
I suggest you to first make sure that your model associations works fine, for that open the console and try the following,
> company = Company.last
=> #<Tcompany id: 1....>
> company.users
=> []
> company.users.build(:name => "Jake")
=> > #<User id: nil, name: "Jake">
> company.save
=> true
Now if the records are being saved fine, debug the parameters you pass to build method.
Happy debugging :)
I have many-to-many relationship between Game and Account models like below:
class Account < ActiveRecord::Base
has_many :account_games, :dependent => :destroy
has_many :games, :through => :account_games
end
class Game < ActiveRecord::Base
has_many :account_games, :dependent => :destroy
has_many :accounts, :through => :account_games
end
class AccountGame < ActiveRecord::Base
belongs_to :account
belongs_to :game
end
Now I know let's say I want to create a record something like:
#account = Account.new(params[:user])
#account.games << Game.first
#account.save
But how am I supposed to update some of the attributes in AccountGame while I'm doing that? Lets say that AccountGame has some field called score, how would I update this attribute? Can you tell me about the best way to do that? To add any field in the through table while I'm saving the object.
#account = Account.new(params[:user])
#accountgame = #account.account_games.build(:game => Game.first, :score => 100)
#accountgame.save
Though I'd strongly recommend that if you start adding columns to your join-model that you call it something different eg "subscription" or "membership" or something similar. Once you add columns it stops being a join model and starts just being a regular model.
This should work:
class AccountGame < ActiveRecord::Base
belongs_to :account
belongs_to :game
attr_accessible :account_id, :game_id #<======= Notice this line
end
First I'm using Rails 3.1 from the 3-1-stable branch updated an hour ago.
I'm developing an application where I have 3 essential models User, Company and Job, Here's the relevant part of the models:
class User < ActiveRecord::Base
has_many :companies_users, class_name: "CompaniesUsers"
has_many :companies, :through => :companies_users, :source => :company
end
class Company < ActiveRecord::Base
has_many :companies_users, class_name: "CompaniesUsers"
has_many :employees, :through => :companies_users, :source => :user
has_many :jobs, :dependent => :destroy
end
class Job < ActiveRecord::Base
belongs_to :company, :counter_cache => true
end
class CompaniesUsers < ActiveRecord::Base
belongs_to :company
belongs_to :user
end
The code works just fine, but I have been wondering if it's possible to:
I want to link a job with an employer, so think of this scenario: A user John who's an employee at Example, he posted the job Rails Developer, so I want to access #job.employer and it should get me back the user John, in other words:
#user = User.find_by_name('john')
#job = Job.find(1)
#job.employer == #user #=> true
So I thought of two possible solutions
First solution
class Job
has_one :employer, :through => :employers
end
class User
has_many :jobs, :through => :employers
end
class Employer
belongs_to :job
belongs_to :user
end
Second solution
class Job
has_one :employer, :class_name => "User"
end
class User
belongs_to :job
end
Which route should I go? Is my code right ?
I have another question, how to get rid of the class_name => "CompaniesUsers" option passed to has_many, should the class be Singular or Plural ? Should I rename it to something like Employees ?
P.S: I posted the same question to Ruby on Rails: Talk
Unless I'm missing something, I'd suggest simply doing
class Job
belongs_to :employer, :class_name => "User"
end
class User
has_many :jobs
end
This would give you methods like
user = User.first
user.jobs.create(params)
user.jobs # array
job = user.jobs.first
job.employer == user # true
You'll need an employer_id integer field in your Jobs table for this to work.
Typically you want to name your pass through model:
company_user
Then you don't need this:
class_name: "CompaniesUsers"
Just make sure the name of your database table is:
company_users
What you have works for you, so that's great. I just find when I don't follow convention I
run in to trouble down the road.
How can I delete nested objects in a form? I found out that I need to add :allow_destroy in the parent model at the accepts_nested_attributes_for directive.
Further, I want to restrict the deletion. A nested object only should be deleted, if the parent object is the only one that retains the association.
Example:
class Internship < ActiveRecord::Base
belongs_to :company
accepts_nested_attributes_for :company, allow_destroy => true
end
class Company < ActiveRecord::Base
has_many :internships
end
Explanation: A company can host many internships. Therefore, I do not want to delete the company record as long as there is at least one other internship associated with it.
You could use dependent => :destroy
class Internship < ActiveRecord::Base
belongs_to :company
accepts_nested_attributes_for :company, allow_destroy => true
end
class Company < ActiveRecord::Base
has_many :internships, :dependent => :destroy
end
If you return false in a before_destroy filter, then the destroy action will be blocked. So we can check to see if there are any internships associated to the company, and block it if so. This is done in the company model.
class Company < ActiveRecord::Base
has_many :internships
before_destroy :ensure_no_internships
private
def ensure_no_internships
return false if self.internships.count > 0
end
end