I am trying to create an association between a User model and an Attendance model in which an attendee_id references a user. The association is a many to many relationship between users and concerts. The join table attendances has two fields
:attendee and :concert.
seed.rb file:
require 'faker'
Concert.destroy_all
User.destroy_all
Attendance.destroy_all
15.times do
Concert.create(band: Faker::RockBand.name, venue: "#{Faker::LordOfTheRings.location}", date: Faker::Date.forward(rand(30)), start_time: "8:00 PM")
end
5.times do |number|
User.create(first_name: Faker::Name.first_name, last_name: Faker::Name.last_name, email: "#{number}#email.com", password: "password")
end
concerts = Concert.all
users = User.all
15.times do
Attendance.create(attendee: users.sample, concert: concerts.sample)
end
Here are the models:
class Attendance < ApplicationRecord
belongs_to :attendee, class_name: "User"
belongs_to :concert
end
class Concert < ApplicationRecord
validates :band, :venue, :date, :start_time, presence: true
has_many :attendances
has_many :attendees, through: :attendances
end
class User < ApplicationRecord
validates :first_name, :last_name, :email, presence: true
validates_format_of :email, with: /#/
has_secure_password
has_many :attendances, foreign_key: :attendee_id
has_many :concerts, through: :attendances
end
Here are the migrations:
class CreateAttendances < ActiveRecord::Migration[5.0]
def change
create_table :attendances do |t|
t.references :attendee
t.references :concert, index: true
t.timestamps
end
end
end
class CreateUsers < ActiveRecord::Migration[5.0]
def change
create_table :users do |t|
t.string :first_name
t.string :last_name
t.string :email
t.string :password_digest
t.timestamps
end
end
end
class CreateConcerts < ActiveRecord::Migration[5.0]
def change
create_table :concerts do |t|
t.string :band
t.string :venue
t.datetime :date
t.time :start_time
t.timestamps
end
end
end
Looks like there are no attendee_id column
bundle exec rails db:reset (same as db:drop + db:create + db:migrate + db:seed)
And for tests bundle exec rails db:test:prepare
If it`s not solve the problem, i think, we need moar stacktraces)
I run bundle exec rake db:drop and then I created the database bundle exec rake db:create and bundle exec rake db:migrate I was then able to seed the database.
Please try to change t.references to special alias t.belongs_to.
It worked for me with Rails 5.2.1
Related
I'm building a sinatra app with Active record. The idea is to essentially have a custom email app. Here I have the models User and Message. A User has_many :messages and a Message belongs_to :user. This may be where I have the issue. I also have it set up for a Message belongs_to :user and has_many :users.
here are the models
Now when I create a message in the action controller I am attempting to use the shove methods to put the new message in a user's messages array. If I attempt to "share" this message with multiple users at once with all the user's id's in params( #user = User.find(id) and then user.messages << #new_message) the last user will have the message stored in it's .messages array. However only the last one to be iterated.
class Message < ActiveRecord::Base
belongs_to :user
has_many :users
end
class User < ActiveRecord::Base
validates :username, presence: true, uniqueness: true
has_secure_password
has_many :messages
end
The idea is the writer "owns" the message but can share it with many users. Here are the tables
class CreateUsers < ActiveRecord::Migration
def change
create_table :users do |t|
t.string :username
t.string :email
t.string :password_digest
end
end
end
class CreateMessages < ActiveRecord::Migration
def change
create_table :messages do |t|
t.string :message
t.string :author
t.integer :user_id
t.integer :user_ids
t.integer :share_id
t.string :title
t.timestamps
end
end
end
# action controller
new_params = {}
new_params[:message] = params["message"]
new_params[:title] = params["title"]
new_params[:author] = params["author"]
new_params[:user_id] = params["user_id"]
#message = Message.create(new_params)
# #share = Share.create
# #message.share_id = #share.id
response.map do |x|
x.messages << #message
x.save!
end
#all = User.all
#user = User.find_by(username: #message.author)
erb :"/user/sent"
I am fairly sure this is because my associations are not set up properly.
You need to have has-and-belongs-to-many relationship between users and messages to implement sharing multiple messages to multiple users. Create an additional record, e.g. MessageShare and do has many to it from both sides:
class MessageShare < ActiveRecord::Base
belongs_to :user
belongs_to :message
end
class Message < ActiveRecord::Base
has_many :message_shares
end
class User < ActiveRecord::Base
has_many :message_shares
end
message_shares table should have user_id and message_id integer columns.
I have my resources:
resources :flows do
resources :fmodules
end
the new method in fmodules controller:
# /flows/1/fmodules/new
def new
#flow = Flow.find(params[:flow_id])
#fmodule = #flow.fmodules.build
end
the models:
class Flow < ApplicationRecord
has_many :fmodules, dependent: :destroy
validates :code, presence: true, length: { maximum: 5 }
validates :name, presence: true
end
class Fmodule < ApplicationRecord
belongs_to :flow
end
When i try to go at /flows/1/fmodules/new ruby says unknown attribute 'flow_id' for Fmodule.
I dont know what is wrong
Here is the migration of Fmodel in addition
class CreateFmodules < ActiveRecord::Migration[5.1]
def change
create_table :fmodules do |t|
t.string :code
t.string :name
t.string :f_code
t.timestamps
end
add_foreign_key :fmodules, :flows, column: :f_code
end
end
So, the problem is that you don't have a flow_id in your fmodules table. In rails, by convention the foreign key is build automatically inferring column name from an argument you pass to belongs_to. That's why rails think that foreign key for flows table is flow_id and it raises exception not finding it. You can overwrite the default with foreign_key option like the following
class Fmodule < ApplicationRecord
belongs_to :flow, foreign_key: : f_code
end
i'm learning Rails and i'm doing an exercise to practice associations and migration files.
Currently, trying to make a models between users, auction item, and bids.
So far for the migrate files I have the following:
class CreateItem < ActiveRecord::Migration
def change
create_table :auction do |t|
t.string :item_name
t.string :condition
t.date :start_date
t.date :end_date
t.text :description
t.timestamps
end
end
end
class CreateBids < ActiveRecord::Migration
def change
create_table :bids do |t|
t.integer :user_id
t.integer :auction_id
t.timestamps
end
end
end
class CreateUsers < ActiveRecord::Migration
def change
create_table :users do |t|
t.string :email
t.string :username
t.string :password_digest
t.timestamps
end
end
end
These are the following models:
class Bid < ActiveRecord::Base
belongs_to :bidder, class_name: "User", foreign_key: "bidder_id"
belongs_to :auction
end
class User < ActiveRecord::Base
has_many :bids
has_many :auctions, :foreign_key => 'bidder_id'
has_secure_password
end
class Auction < ActiveRecord::Base
belongs_to :seller, class_name: "User", foreign_key: :user_id
has_many :bids
has_many :bidders, through: :bids
end
Any suggestions or opinions? I'm currently trying to test the tables but auctions doesn't seem to be working...
Specifically, my auction table can't seem to find a user_id and therefore a user doesn't have any auctions.
foreign_key refers to the _id (by default) or any unique attribute used to associate the models.
I can't see bidder model, you need to replace them with user_id as they are associated to user model.
Refer for more details belongs_to
class CreateBids < ActiveRecord::Migration
def change
create_table :bids do |t|
t.integer :user_id **do not think this is correct**
t.integer :auction_id **or this one**
t.timestamps
end
end
end
You want to use something more along the lines of the following
class CreateGames < ActiveRecord::Migration[5.0]
def change
create_table :games do |t|
t.integer :total_time
t.references :version, foreign_key: true **#this is how a foreign key should be declared**
t.integer :total_points
t.timestamps
end
end
end
Alternatively, if you want to change things in future migrations you can always add a reference:
def change
add_reference :levels, :version, foreign_key: true
end
These are my tables:
create_table :messages do |t|
t.integer :type
t.string :text
t.datetime :sent_date
t.string :sender
t.timestamps
end
create_table :users do |t|
t.integer :phone
t.string :fullname
t.string :profile_image
t.timestamps
end
create_table :send_tos do |t|
t.string :receiver
t.belongs_to :message
t.boolean :is_received
end
and these are the model classes:
class User < ActiveRecord::Base
has_many :send_tos, :foreign_key => 'receiver'
has_many :messages, :foreign_key => 'sender'
end
class Message < ActiveRecord::Base
belongs_to :user, :foreign_key => 'sender'
has_many :send_tos
end
class Send_to < ActiveRecord::Base
belongs_to :user, :foreign_key => "receiver"
belongs_to :message
end
When I run these commands on rails console:
m = Message.new
m.save
s = Send_to.new
s.message = m
s.save
m.send_tos
After command m.send_tos I get this error:
RuntimeError: Circular dependency detected while autoloading constant
SendTo
Why am I getting this error? What should I do to change it?
Change the name of the Send_to class to SendTo. This follows the naming convention that Rails assumes for its relationships. The name of the file it is in should be send_to.rb
Let me explain :
I followed the M. Hartl tutorial and I did just like him with migrations. So now, I have the followings files in my db/migrate directory (I spare you the timestamps):
create_users.rb
class CreateUsers < ActiveRecord::Migration
def change
create_table :users do |t|
t.string :name
t.string :email
t.timestamps
end
end
end
add_index_to_users_email.rb
class AddIndexToUsersEmail < ActiveRecord::Migration
def change
add_index :users, :email, unique: true
end
end
add_password_digest_to_users.rb
class AddPasswordDigestToUsers < ActiveRecord::Migration
def change
add_column :users, :password_digest, :string
end
end
add_remember_token_to_users.rb
class AddRememberTokenToUsers < ActiveRecord::Migration
def change
add_column :users, :remember_token, :string
add_index :users, :remember_token
end
end
add_admin_to_users.rb
class AddAdminToUsers < ActiveRecord::Migration
def change
add_column :users, :admin, :boolean, default: false
end
end
Is it possible to mix everything into create_users.rb like following, and delete the others migration files without any damage to my app ?
create_users.rb
class CreateUsers < ActiveRecord::Migration
def change
create_table :users do |t|
t.string :name
t.string :email
t.string :password_digest
t.string :remember_token
t.boolean :admin, default: false
t.timestamps
end
add_index :users, :email, unique: true
add_index :users, :remember_token
end
end
Yes, it is possible. A straighforward strategy for that might be:
In order to avoid data loss, make a database dumb (create a DB backup)
Drop and recreate the database:
rake db:drop db:create
Have all migrations merged into a single file like you've shown
Run:
rake db:migrate
Restore the DB backup
Though, this may become tricky if you already have the application deployed on production.