So I have been trying to create a dummy application to try and learn Rails. The app I thought I could create is a coffee ordering app for a group of people in work.
So the website will have many users.
A user can create a coffee_order.
A coffee order contains orders for other individual users.
Each user can have one or more coffee_shop_items (e.g. latte,
cappuccino,danish, muffin, etc)
A coffee order also has an assignee, this is the person who is tasked
with going and getting the order.
So as a user, I create a coffee order, select an assignee, add users to the order, and add one or more coffee shop items to each user,
I am really struggling with how the database should be, and what the associations need to be, along with any join tables?
I am also trying to use nested attributes for the form entry.
Thanks in advance for help.
Update with some code I have tried to create a coffee order:
#coffee_order = CoffeeOrder.new(coffee_order_params)
params[:coffee_order][:user_coffee_orders_attributes].each do |user_order|
order = #coffee_order.user_coffee_orders.new(user_id: user_order[1][:user_id].to_i)
user_order[1][:coffee_shop_items].each do |item|
coffee_shop_item = CoffeeShopItems.find(item) if item != ""
# this line fails! see error below
#coffee_order.user_coffee_orders.coffee_shop_items << coffee_shop_item if coffee_shop_item != nil
end
end
error:
NoMethodError (undefined method `coffee_shop_items' for #<UserCoffeeOrder::ActiveRecord_Associations_CollectionProxy:0x42c6180>):
The coffee_shop_items belong to the order, not the user. After all, a user could probably create another order another day? You should probably also check out the rails documentation, which, IIRC actually contains a walk-through of a shopping cart application.
User has_many :coffes_orders
User has_many :coffee_orders_he_needs_to_get, class_name: "CoffeeOrder", foreign_key: "assignee_id"
CoffeeOrder belongs_to :user
CoffeeOrder belongs_to :assignee, class_name: "User"
CoffeeOrder has_and_belongs_to_many :coffee_shop_items
Coffee_shop_items has_and_belongs_to_many :coffee_orders
Related
i'm new to rails and your help and advise would be much appreciated as i am finding this challenging
Aim: i want the creator of the event to be able to select more than one user as
hosts for a created event (just like how facebook allows the creator of
a page to be be able to select users as admins of a created page). Is the below how my model and schema should be displayed?
i was aiming to build something like this image. Event1 i can select Ian & Jesse as hosts, Event2 i can also select Ian again as a host and select Emma
This is how i imagine it so far to be built (your guidance would be much appreciated):
models
user.rb
has_many events
event.rb
belongs_to user
host.rb
belongs_to user
has_many events
schema
users
name
email
events
title
address
user_id
hosts
user_id
event_id
Started writing this as a comment but realised it was getting too wordy.
your model is broken ... an event has many users .. it doesn't belong_to a single user.
What you have is a many to many relationship between users and events which needs resolving through a join table (aka associative/junction table). You have gone some way to resolving this with the hosts table though this goes against the rails convention.
What you want is something like:
models
user.rb
has_and_belongs_to_many :events
event.rb
has_and_belongs_to_many :users
and create a join table that references the two models
users table
name
email
events table
title
address
events_hosts table
user_id
event_id
The rails convention is for the join table to be named by joining the two names of the tables it is joining lexically ordered - i.e. events before hosts, concatenated together to give events_hosts.
Alternatively, you can also create a join model if you prefer:
EventHost
belongs_to :user
belongs_to :event
and modify the has_and_belongs_to_many to has_many :event_hosts in the other two models - the database schema will remain the same.
I have a Boat Model and its Models such as Brand, Model and Year. I have also User model and I would like to connect them by adding migrations to User model of boat_id and I added belongs_to :boat and has_many :boats to User model. But I can not reach User.first.boat.name from the console even though I am able to reach Boat.first.brand.name.
When I try User.first.boat.name. Console gives an error saying;
NoMethodError: undefined method `boat' for #<User:0x0000000665dc30>
Btw: Boat Model includes model_id brand_id and year_id.
EDIT1:
Or should i remove Boat model and add model_id brand_id and year_id to User model directly.
EDIT2:
I would like to be able to reach User.first.boat.brand.name or User.first.boat.year.nameor User.first.boat.model.name
EDIT3:
Every boat has one brand, year and model. But user can have many boats
EDIT4:
What i will do is;
User can sign up and login
Then User press the link list my boat.
He/she saves the boat then the page renders to User Profile
In the User profile I do not know how to get current user boat name year etc. That is why I am confused. Sorry for the misunderstanding
I think you're confused about how Rails associations work in conjunction with how they are stored in the database. If a User can have many boats, then the foreign key needs to be on the boats table. Currently you have boat_id in the users table, this should be removed and a user_id column needs to be added to the boats table as per Matt's answer.
Reference
To achieve what you're trying to do, you'll need to setup your models in the following manner:
class User
has_many :boats
...
end
class Boat
belongs_to :user # table has a user_id column
...
end
Then you can access a boat's brand using user.boats.first.brand.name
Run rails generate migration, then fill in the change method as follows:
def change
add_column :boats, :user_id, :integer
end
Then run rake db:migrate.
You user model has_many boats, so you need the boats table to refer to users. It's probably worth reading the Rails guide for ActiveRecord associations to get a better feel for how this works: http://guides.rubyonrails.org/association_basics.html#the-has-many-association
So many tutorials on how to set up a has_many :through but not enough on how to actually do it!
I have a Inventories and Requests table joined by Bookings. Example: there could be 3 lenders who have tents in inventory, each of which is requested by 3 other borrowers. What I want to do is for each of the 3 tents in inventory, show that lender the list of 3 borrowers who requested the tent. Then the lender can pick who s/he wants to be the ultimate borrower.
I have thoughts on how this should work, but no idea if it's right, so please give advice on the below! The action is driven all by the Requests controller. Let's run through an example where the Inventories table already has 3 tents, ids [1, 2, 3]. Let's say Borrower Pat submits a Request_ID 1 for a tent.
Am I then supposed to create 3 new Bookings all with Request_ID 1 and then Inventory_ID [1, 2, 3] to get all the conceivable combinations? Something like
Inventory.where(name: "tent").each { |inventory| #request.bookings.create(inventory_id: inventory.id) }
And then is it right to use the Bookings primary key as the foreign key in both the Request and Inventory? Which means that after Borrower Pat submits his request, the bookings_id will be blank until say Lender 2 accepts, at which point bookings_id equals the id that matches the combination of Request_ID 1 and Inventory_ID 2
Now let's say when a Request is posted and a Bookings is made, I email the lender. However, I realized I don't want to bother Lender Taylor if 3 borrowers want her tent over the same time period. I'll just email her the first time, and then the subsequent ones she'll find out about when she logs in to say yes or no. In this situation is it OK to just query the Bookings table in the create action, something like (expanding off above)
-
Inventory.where(name: "tent").each do |inventory|
if !Bookings.find_by_inventory_id(inventory.id).exists?
# If there are no other bookings for this inventory, then create the booking and send an email
#request.bookings.create(inventory_id: inventory.id)
AlertMail.mail_to_lender(inventory).deliver
else
# If there are other bookings for this inventory, do any of those bookings have a request ID where the requested time overlaps with this new request's requested time? If so then just create a booking, don't bother with another email
if Bookings.where(inventory_id: inventory.id).select { |bookings_id| Bookings.find_by_id(bookings_id).request.time overlaps_with current_request.time }.count > 0
#request.bookings.create(inventory_id: inventory.id)
# If there are other bookings for this inventory but without overlapping times, go ahead and send an new email
else
#request.bookings.create(inventory_id: inventory.id)
AlertMail.mail_to_lender(inventory).deliver
end
end
end
Code above is probably flawed, I just want to know the theory of how this is supposed to be working.
Join Table
Firstly, has_many :through works by using a join table - a central table used to identify two different foreign_keys for your other tables. This is what provides the through functionality:
Some trivia for you:
has_and_belongs_to_many tables are called [plural_model_1]_[plural_model_2] and the models need to be in alphabetical order (entries_users)
has_many :through join tables can be called anything, but are typically called [alphabetical_model_1_singular]_[alphabetical_model_2_plural]
--
Models
The has_many :through models are generally constructed as such:
#app/models/inventory.rb
Class Inventory < ActiveRecord::Base
has_many :bookings
has_many :requests, through: :bookings
end
#app/models/booking.rb
Class Booking < ActiveRecord::Base
belongs_to :inventory
belongs_to :request
end
#app/models/request.rb
Class Request < ActiveRecord::Base
has_many :bookings
has_many :requests, through: :bookings
end
--
Code
Your code is really quite bloated - you'll be much better doing something like this:
#app/controllers/inventories_controller.rb
Class InventoriesController < ApplicationController
def action
#tents = Inventory.where name: "tent"
#tents.each do |tent|
booking = Booking.find_or_create_by inventory_id: tend.id
AlertMail.mail_to_lender(tent).deliver if booking.is_past_due?
end
end
end
#app/models/booking.rb
Class Booking < ActiveRecord::Base
def is_past_due?
...logic here for instance method
end
end
Used find_or_create_by
You should only be referencing things once - it's called DRY (don't repeat yourself)
I did a poor job of asking this question. What I wanted to know was how to create the actual associations once everything is set up in the DB and Model files.
If you want to create a record of B that is in a many-to-many relationship with an existing record of A, it's the same syntax of A.Bs.create. What was more important for me, was how to link an A and B that already existed, in which case the answer was A.B_ids += B_id.
Two other things:
More obvious: if you created/ linked something one way, was the other way automatic? And yes, of course. In a many-to-many relationship, if you've done say A.B_ids += B_id, you no longer have to do 'B.A_ids += A_id`.
Less obvious: if A and B are joined by table AB, the primary key of table AB doesn't need to be added to A or B. Rails wants you to worry about the AB table as less as possible, so searches, builds, etc. can all be done by A.B or B.A instead of A.AB.B or B.AB.A
Right now I have a simple blog website setup with devise which allows users to edit posts. I also have activeadmin installed on the backend. What I want is when a user signs in and they edit a post I want that users email to be tied to that post. Then I could go into active admin and setup the column to view the user later. Trouble im having is that im not sure how to automatically tag a users email to a specific post when they edit it, also my user and post model are on different tables in the database.
Thanks for any help.
http://guides.rubyonrails.org/association_basics.html#the-has_and_belongs_to_many-association
Just set up a join table for a has_and_belongs_to_many association on each model. This is a standard active record association which should be well-documented; see the link above for a start.
Then in your update method for the PostsController you can add a line like:
#post.users << current_user
(obviously the specific code will vary depending on the names of your variables & associations -- i'd probably rename the association to "editors" or something like that)
I don't know anything about active admin, so I can't tell you how to make these associations viewable there. But it shouldn't be too hard once the association is set up properly.
Two approaches I use to create user_stamps.
paper_trail gem that records all modifications in Version table.
Works great with Active Admin.
Adding updated_by_id and created_by_id columns to all tables (paper_trail needed)
# In each Model.
belongs_to :updated_by, :class_name => "AdminUser", :foreign_key => "updated_by_id"
belongs_to :created_by, :class_name => "AdminUser", :foreign_key => "created_by_id"
after_create { |i| i.update_column(:created_by_id, PaperTrail.whodunnit) }
after_save { |i| i.update_column(:updated_by_id, PaperTrail.whodunnit) }
These columns will be redundant but a great compliment to Version table and is faster and better for many reports and scopes.
I am starting to create my sites in Ruby on Rails these days instead of PHP.
I have picked up the language easily but still not 100% confident with associations :)
I have this situation:
User Model
has_and_belongs_to_many :roles
Roles Model
has_and_belongs_to_many :users
Journal Model
has_and_belongs_to_many :roles
So I have a roles_users table and a journals_roles table
I can access the user roles like so:
user = User.find(1)
User.roles
This gives me the roles assigned to the user, I can then access the journal model like so:
journals = user.roles.first.journals
This gets me the journals associated with the user based on the roles. I want to be able to access the journals like so user.journals
In my user model I have tried this:
def journals
self.roles.collect { |role| role.journals }.flatten
end
This gets me the journals in a flatten array but unfortunately I am unable to access anything associated with journals in this case, e.g in the journals model it has:
has_many :items
When I try to access user.journals.items it does not work as it is a flatten array which I am trying to access the has_many association.
Is it possible to get the user.journals another way other than the way I have shown above with the collect method?
Hope you guys understand what I mean, if not let me know and ill try to explain it better.
Cheers
Eef
If you want to have user.journals you should write query by hand. As far as I know Rails does has_many :through associations (habtm is a kind of has_many :through) one level deep. You can use has_many with finder_sql.
user.journals.items in your example doesn't work, becouse journals is an array and it doesn't have items method associated. So, you need to select one journal and then call items:
user.journals.first.items
I would also modify your journals method:
def journals
self.roles(:include => :journals).collect { |role| role.journals }.flatten.uniq
end
uniq removes duplicates and :inlcude => :journals should improve sql queries.
Similar question https://stackoverflow.com/questions/2802539/ruby-on-rails-join-table-associations
You can use Journal.scoped to create scope with conditions you need. As you have many-to-many association for journals-roles, you need to access joining table either with separate query or with inner select:
def journals
Journal.scoped(:conditions => ["journals.id in (Select journal_id from journals_roles where role_id in (?))", role_ids])
end
Then you can use user.journals.all(:include => :items) etc