I have users and companies in a many to many relationship by a join table which has a column for user Role. I'm not sure if this is the best way to have the model set up.
Now each user can have different roles depending on the company, what is the best way to design and access user's role using ActiveRecord associations?
I would like to return via JSON the user's role based on their current company and default to something if their company is nil OR their role has not been set (nil).
Update:
What I've got now after reading Many-to-many relationship with the same model in rails? which is a bit different (many to many on itself).
CompaniesUser
belongs_to :company
belongs_to :user
Company
has_many(:companies_users, :dependent => :destroy)
has_many :users, :through => :companies_users
User
has_one :company
has_many(:companies_users, :dependent => :destroy)
has_many :companies, :through => :companies_users
Appreciate any advice as I'm just starting to learn this!
What you have above is correct, in terms of the ActiveRecord relationships. If you'd like to read more on the subject I believe this is the best source: http://guides.rubyonrails.org/association_basics.html
One problem I see there is that CompaniesUsers should be in singular form: CompanyUser, and then in all cases where you use :companies_users use: :company_users
I am assuming here that the current company of the User is the last one assigned.
Now in order to serialize in JSON format you should add the following in your User ActiveRecord:
def serializable_hash(options = nil)
options ||= {}
h = super(options)
if(defined?self.company_users.last and defined?(self.company_users.last).role)
h[:role] = (self.company_users.last).role
else
h[:role] = 'default_value'
end
end
Related
In my app (Rails 4.2.0.rc2), users can be either students or admins of a given institution. There's an association :admin_institutions on User that returns all the institutions the user is an admin of by checking their role in the join table. There's also an association :students on Institution that returns all the users who are students at that institution, again according to institution_users.role.
These associations work as expected, so I added an association :admin_students to User, meant to return all the students at all the institutions for which a given user is an admin.
class InstitutionUser < ActiveRecord::Base
belongs_to :institution
belongs_to :user
end
class Institution < ActiveRecord::Base
has_many :institution_users
has_many :users, :through => :institution_users
has_many :students, -> { where "institution_users.role = 'Student'" }, :through => :institution_users, source: :user
...
end
class User < ActiveRecord::Base
has_many :institution_users
has_many :admin_institutions, -> { where "institution_users.role = 'Admin'" }, through: :institution_users, source: :institution
has_many :admin_students, through: :admin_institutions, source: :students
...
end
However, :admin_students does not work as expected. It generates the following SQL:
SELECT "users".* FROM "users" INNER JOIN "institution_users" ON "users"."id" = "institution_users"."user_id" INNER JOIN "institutions" ON "institution_users"."institution_id" = "institutions"."id" INNER JOIN "institution_users" "institution_users_admin_students_join" ON "institutions"."id" = "institution_users_admin_students_join"."institution_id" WHERE "institution_users_admin_students_join"."user_id" = $1 AND (institution_users.role='Student') AND (institution_users.role = 'Admin') [["user_id", 190]]
Instead of looking for all the institutions where the user is an admin and selecting all their students, it seems to be looking for institutions where the user is BOTH a student and an admin, so it returns an empty collection.
Is there a way to write an association (as opposed to just a method) that will give me the results I want, without my conditions conflicting like this?
(Side note: Is this the expected behavior for this kind of association? If so, I'd really appreciate further insight into why ActiveRecord interprets it the way it does.)
This may not be the answer, but maybe it will lead to one.
I'm not a fan of the associations with hard-coded SQL:
-> { where "institution_users.role = 'Student'" }
They are definitely at least part of the problem because they cannot be interpreted by ActiveRecord to determine which table alias for institution_users to apply it to.
You can allow ActiveRecord that flexibility by referencing a class method of the InsitutionUser model:
def self.students
where(role: "Student")
end
This also keeps the InstitutionUser logic all in one place.
Then the association becomes:
has_many :students, -> {merge(InstitutionUser.students)}, :through => :institution_users, source: :user
Perhaps try it with this and see if that sorts it out for you, and if not it might get things going in the right direction.
I am trying to allow users to search through their own friends by email address. I'd like to do something like:
current_user.search('test#fake.com')
and have it return an array of current users friends that have that email address.
So I have a very basic friendship relationship set up on my user model
user.rb
has_many :friendships
has_many :friends, through: :friendships, source: :friend
has_many :inverse_friendships, class_name: 'Friendship', foreign_key: 'friend_id'
has_many :inverse_friends, through: :inverse_friendships, source: :user
friendship.rb
belongs_to :friend, class_name: 'User', foreign_key: 'friend_id'
belongs_to :user
I want to set up a method on my user model that can search through their friends by email address. It's not working so well
def search(query)
conditions = ['friends.user_id = ? AND email LIKE ? ', self.id, "%#{query}%"]
User.includes(:friends).where(conditions)
end
I guess I'm just not sure how to format my active record query / SQL here, since I am trying to search on the relations of a self referential model. Any one have any ideas?
Thanks!
Digital Cake is going in the right direction, but not exactly correct. A scope is a method of User, not user. What you need is:
def followers_by_email(email)
friends.where("email like ?", "%#{email}%")
end
This returns an ActiveRecord::Relation to which you can chain other conditions, order, paginate, etc as in
user.followers_by_email("me#example.com").order(:first_name).limit(10)
Good time to use active record scopes. http://guides.rubyonrails.org/active_record_querying.html#scopes
Heres a simple example
user.rb
scope :followers, friends.where(:published => true).order("created_at DESC").limit(150)
in your controller
#followers = User.followers
I seem to have some success with:
conditions = ['contacts.user_id = ? AND users.email LIKE ? ', self.id, "%#{query}%"]
User.includes(:inverse_friends).where(conditions)
Though it's strange that it works, I'm not entirely sure why it does.
I have a small app which has Users, Recipes, Ingredients and preparation models
A user has many recipes, recipes belong to user and ingredients/preparation belongs to recipes.
Now a user can view all recipes but I would like the option to add the particular recipe to a favourites list. Would I need to set a new DB to hold this and then link by associations or could I add a column to the recipe model called fav for example?
Im looking for the best practice here or if someone has done this before and can offer any advice that would be appreciated
I think you can set has_may association like this:
class User < ActiveRecord::Base
has_many :favorite_recipes, foreign_key: "user_id", class_name: "Recipe", dependent: :destroy
end
I would add a boolean column favorited to your UsersRecipe table.
Then you can add a scope for this in your User model:
has_many :favorite_recipes, :through => :user_recipes, :class => Recipe, :conditions => ['user_recipes.favorited = ?',true]
I am new to Rails and finished Michael Hartl's "Ruby on Rails 3 Tutorial". Although the book teaches me a lot, I find this puzzle I don't understand.
To preview the puzzle, that is, I don't understand, inside User model,
has_many :following, :through=>:relationship, :source=>:followed
how this piece of code link "user.following" to an array of User instances.
And below is the whole puzzle.
First of all, I have the Relationship model, which records followed_id and follower_id infos. Inside Relationship model, the association is simple as
class Relationship < ActiveRecord::Base
attr_accessible :followed_id
belongs_to :follower, :class_name => "User"
belongs_to :followed, :class_name => "User"
end
Then, inside the User model, a user will assume the role of follower, and collect all its following rows in relationships table through relationships association.
class User < ActiveRecord::Base
.
.
.
has_many :relationships, :foreign_key => "follower_id", :dependent => :destroy
.
Until now, I got it.
But confusion came at the next line, where through user.following it can assemble all that user's following(User instances). Like so,
has_many :following, :through=>:relationships, :source=>:followed
I understand that :source=>:followed will overwrite the default, and let find all followed_ids associated with that user.
But, how can Rails recognize followed_id to link to User object? The label name doesn't match users, nor is there :class_name specified. I just don't get how Rails do this underlying work, or I missed out some hints.
Thank you! :)
But, how can Rails recognize followed_id to link to User object? The
label name doesn't match users, nor is there :class_name specified. I
just don't get how Rails do this underlying work, or I missed out some
hints.
Rails recognize that is an user object because it is set in Relationship's belongs_to. What Rails does here is to follow the relationship class through the foreign key "follower_id" and returning every User that has a relationship with the current user as followed. Of course Rails do that in a single SQL statement like this:
SELECT `users`.* FROM `users` INNER JOIN `relationships` ON `relationships`.followed_id = `users`.id WHERE ((`relationships`.follower_id = <the current user id> ))
has_many :following, :through=>:relationships, :source=>:followed
This explains to Rails that following is the inverse relationship of following and that users has many following and followed through his relationships.
The way Rails knows that followed_id is linked to User is that it is defined in your Relationship model.
Hope you've understood ! Good luck :)
I have a simple question, but can't seem to find any solution, though I have found things that are similar, but just not exactly what I am looking for.
I have an application where a User has many Assets through the class UserAsset. I want to be able to do current_user.user_assets , but I only want to return records that have an Asset with a specified field value of "active".
This post is similar but I need to use the main model not the join model as a filter.
class UserAsset < ActiveRecord::Base
belongs_to :asset
belongs_to :user
end
class Asset < ActiveRecord::Base
has_many :user_assets
has_many :users, :through => :user_assets
end
class User < ActiveRecord::Base
has_many :user_assets
has_many :assets, :through => :user_assets
end
I tried setting the default scope on Asset, and also some conditions on the has many (user_assets) relationship, but rails is failing to consider the join on the Assets table. ie Unknown column 'asset.live' in 'where clause'. Trying to achieve the following:
#active_user_assets = current_user.user_assets #only where assets.active = true
So how do I use conditions or scopes to achieve this? I need the user_asset object because it contains info about the relationship that is relevant.
Thanks in advance!
You want current_user.assets, then your scopes should work.
Oh, but you want the user_assets. Hmm. I think you need the :include clause to find() but where to put it, I can't be arsed to think of right now.
Perhaps
current_user.user_assets.find(:all, :include => :assets).where('asset.live=?', true)
(I'm not on Rails 3 yet, so that's going to be mangled)
Are you using :through when you really want a HABTM?