I have a Course and Lesson models. Course has several lessons. I want to find all the lessons for currently logged in student to generate kind of timetable.
I have a method that returns all the courses that this student is studying. Now I want to get all lessons from all those courses in #courses into #lessons, something like:
def index
#courses = current_student.find_courses
#lessons = #courses.lessons
end
Is it possible to do it somehow simple on one line?
The find_courses method is implemented as following:
def find_courses
Course.where("id IN (?)", StudentAssignment.select("course_id").where('student_id == (?)', self.id))
end
The Models:
class Student < ApplicationRecord
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable, :trackable and :omniauthable
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :validatable
has_many :student_assignments
has_many :courses, :through => :student_assignments
....
class Lesson < ApplicationRecord
belongs_to :room
belongs_to :teacher
belongs_to :course
....
class Course < ApplicationRecord
has_many :lessons, dependent: :destroy
has_many :teacher_assignments
has_many :teachers, :through => :teacher_assignments
has_many :student_assignments
has_many :students, :through => :student_assignments
...
class Student < ApplicationRecord
has_many :courses
def active_lessions
Lession.joins(course: :students).where(students: {id: self.id})
end
end
In this way you can directly get all active lesssions for current_user
current_student.active_lessions
Try:
#lessons = #courses.flat_map(&:lessons)
It takes each course in #courses list and gets the list of lessons for that course.
Related
I have three models and here they are when I try to create a has_many. I basically want my users (using devise) to have many categories. And categories to have many users.
user.rb
class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable,
:omniauthable
has_many :user_categories
has_many :categories, through: :user_categories
acts_as_messageable
def mailboxer_email(object)
email
end
end
userCategory.rb
class UserCategory < ActiveRecord::Base
belongs_to :user
belongs_to :category
accepts_nested_attributes_for :categories
end
Category.rb
class Category < ActiveRecord::Base
has_many :user_categories
has_many :user, through: :user_categories
validates :name, presence: true, length: {minimum: 3, maximum: 25}
validates_uniqueness_of :name
end
when I run category.users << user I get this error:
ActiveRecord::HasManyThroughAssociationNotFoundError: Could not find the association :user_categories in model Category
I can't say for sure what the problem could be, but a few things I could point out:
UserCategory's accepts_nested_attributes_for, does that mean the you want to be able to dynamically create categories?
Category has_many :users, through: :user_categories, not user
You need to follow the Rails file naming conventions, user.rb, user_category.rb and category.rb
These may not be the problem/solution, but I believe they're in the way of resolving the problem.
I want to make audits for nested associations like I have
User has_many addresses i.e either
HomeAddress or OfficeAddress
Now if I have just one table Address and I have used type and id for differentiating them.In this case if I use associated_audits for User then it will make just one audit record and whenever I update the record again ,its just replacing the previous audit with the last one.
Here is the models association:
class Patient < ActiveRecord::Base
devise :database_authenticatable, :registerable, :recoverable, :rememberable,
:trackable, :validatable, :confirmable, request_keys: [:subdomain]
has_one :home_address,-> { where(addr_type: 'home') },class_name: 'Address'
has_one :office_address,-> { where(addr_type: 'office') }, class_name: 'Address'
has_associated_audits
accepts_nested_attributes_for :home_address, allow_destroy: true
accepts_nested_attributes_for :office_address, allow_destroy: true
end
class Address < ActiveRecord::Base
belongs_to :patient
audited
end
class Address < ActiveRecord::Base
belongs_to :patient
audited associated_with: :patient
end
class Patient < ActiveRecord::Base
has_many :addresses
has_associated_audits
end
Let's say I have 3 models in my Rails app... Establishment, WasteType and EstablishmentWaste... My problem is that I want to get all establishments associated with a certain wastetype. This normally would be done with Establishment.where(waste_type_id: some_number), the problem is that Establishment has many WasteType and vice versa, and the association is made through a third party...
Any help?
Classes and data model below
Establishment
class Establishment < ActiveRecord::Base
# Include default devise modules.
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable, :omniauthable
has_many :containers
has_many :establishment_wastes
has_many :waste_types, through: :establishment_wastes, :foreign_key => 'establishment_id'
include DeviseTokenAuth::Concerns::User
end
WasteType
class WasteType < ActiveRecord::Base
has_many :containers
has_many :establishment_wastes
has_many :establishments, through: :establishment_wastes, :foreign_key => 'waste_type_id'
end
EstablishmentWaste
class EstablishmentWaste < ActiveRecord::Base
belongs_to :establishment, :foreign_key => 'establishment_id'
belongs_to :waste_type, :foreign_key => 'waste_type_id'
end
So the data model would be like these
EstablishmentWaste is a join table in this case so the query should be.
Establishment
.joins(:establishment_wastes)
.where('establishment_wastes.waste_type_id = ?', some_number)
Quick tip! You do not need to assign :foreign_key => 'establishment_id' since it is default Rails behavior to assign a foreign key to model_id.
Here is my join model:
class CompanyUser < ActiveRecord::Base
belongs_to :company
belongs_to :user
end
My User model:
class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable
ROLES = %w[admin requestor requestor_limited shipping_vendor].freeze
attr_accessor :temp_password
has_many :companies_users
...
end
If I run this in the console:
u = User.first
u.companies
This is the error I am getting:
NameError: uninitialized constant User::CompaniesUser
has_many through relationships should be like this:
In app/models/company.rb file,
has_many :company_users
has_many :users, :through => :company_users
In app/models/user.rb file,
has_many :company_users
has_many :companies, :through => :company_users
In app/models/company_user.rb file,
belongs_to :company
belongs_to :user
If you want to delete the dependent records in company_users table when deleting companies/users,
Add, , :dependent => :destroy at the end of has_many relations in Company and User model.
Hope this helps you..
Thanks.!!
it must be
has_many :company_users
"CompanyUser".tableize => "company_users"
The model shall be either:
class CompaniesUser < ActiveRecord::Base
belongs_to :company
belongs_to :user
end
Or has_many declaration sheel be defined explicitly as:
class User < ActiveRecord::Base
has_many :company_users
end
Hi I have a many to many association where 'posts' have many 'feeling', I'd like to figure out how to find all the posts with a specific feeling by the user. My Feeling model has a 'name' attribute.
class User < ActiveRecord::Base
has_many :posts, :dependent => :destroy
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable
end
class Post < ActiveRecord::Base
has_many :feelingships
has_many :feelings, :through => :feelingships
belongs_to :user
end
class Feeling < ActiveRecord::Base
has_many :feelingships
has_many :posts, :through => :feelingships
end
class Feelingship < ActiveRecord::Base
belongs_to :post
belongs_to :feeling
attr_accessible :post_id, :feeling_id
end
I tried this but it says I have the wrong association: "ActiveRecord::ConfigurationError: Association named 'feeling' was not found; perhaps you misspelled it?"
def feeling
#user = User.find(params[:id])
#feed_items= #user.posts.includes(:feeling).where(
['`feelings`.name = ?', params[:feeling]])
#feed_items = #feed_items.paginate(:per_page => "10", :page => params[:page])
render 'shared/_feed', :layout => 'head_layout'
end
The includes argument should be :feelings - notice the plural, which is what your association is named.
So it should be:
#user.posts.includes(:feelings)