Hey there,
Im fairly new to rails and i've tried several tutorials which taught me how to use the associatives on a basic level(has_many => belongs_to).
However i'm trying to figure out how i can create and execute some kind of a join. My case is: I've got a list of playing cards in my DB that are static. Every user can have any of those cards, even multiple times. So my tables would look something like this:
users id = 1 name => "Bear Grylls"
id => 2 name => "Poopypants"
Check out the guide to associations. It should have more information than you need…
Hey!
Associats are covered in great detail here:
I think what you need is a has_many :through association
-- Manuel
Thanks you guys, i've actually tried that(And failed) Perhaps you guys can help me out. I have to following files:
card_controller.rb class CardController < ApplicationController has_many :cardlevels has_many :users, :through => :cardlevels def show @cards = Card.find(1) end end
I seem to have it up and running at this point. I made all the has_many's etc. in my models. But when i try @cards.user (Or each it first and use c.user) it says 'undefined method 'user''. So i'm assuming i'm doing something awfully wrong.
My card_controller looks like this def show @cards = Card.all end
Here are my models: card.rb class Card < ActiveRecord::Base has_many :cardlevels has_many :users, :through => :cardlevels end
I seem to have it up and running at this point. I made all the has_many's etc. in my models. But when i try @cards.user (Or each it first and use c.user) it says 'undefined method 'user''. So i'm assuming i'm doing something awfully wrong.
My card_controller looks like this def show @cards = Card.all end
Here are my models: card.rb class Card < ActiveRecord::Base has_many :cardlevels has_many :users, :through => :cardlevels end -------------------------------------------------
cardlevel.rb class Cardlevel < ActiveRecord::Base belongs_to :users belongs_to :cards
Those should both be singular (:user and :card). Each cardlevel belongs to one user and card so they should be singular.
Colin
Colin Law wrote in post #1065209:
Post the code for the models, the code that generates the error (with a few lines each side) and the full error message.
Colin
I've just got a really basic setup to see if i got it working:
card.rb class Card < ActiveRecord::Base attr_accessible :attack, :defense, :name has_many :cardlevels has_many :users, :through => :cardlevels end
cardlevel.rb class Cardlevel < ActiveRecord::Base attr_accessible :card_id, :level, :user_id belongs_to :user belongs_to :card end
user.rb class User < ActiveRecord::Base attr_accessible :name has_many :cardlevels has_many :cards end
@card is a collection of cards (that's how you populate it in the "show" action. If it needs to be a single card, you need to find it by ID (or some other attribute), if it's supposed to be a collection of every card, you need to iterate it in the view and print the user for each card.
I've just got a really basic setup to see if i got it working:
card.rb class Card < ActiveRecord::Base attr_accessible :attack, :defense, :name has_many :cardlevels has_many :users, :through => :cardlevels end
cardlevel.rb class Cardlevel < ActiveRecord::Base attr_accessible :card_id, :level, :user_id belongs_to :user belongs_to :card end
user.rb class User < ActiveRecord::Base attr_accessible :name has_many :cardlevels has_many :cards end -----------------------------------------------------
card_controller.rb class CardController < ApplicationController def show @card = Card.all
You would have been better to put @cards = Card.all as the result will be be an (effectively) an array of cards not a single one.
end end
User & cardlevel are empty for now -----------------------------------------------------
<h1>Card#show</h1> <p>Find me in app/views/card/show.html.erb</p> <%= @card.user %> Where i tried eaching the @card, tried @card.users, @card.user.name etc. etc. -----------------------------------------------------
The error: Showing c:/tuts/kaartje/app/views/card/show.html.erb where line #3 raised:
undefined method `user' for #<Array:0x3c81ac8>
The clue is in the error message, as is often the case, it says that @card is an Array and the Arrray class does not have a method user. You can only call user on an individual card.
Colin
Michael Pavling wrote in post #1065301:
undefined method `user' for #<Array:0x3c81ac8> Extracted source (around line #3):
@card is a collection of cards (that's how you populate it in the "show" action. If it needs to be a single card, you need to find it by ID (or some other attribute), if it's supposed to be a collection of every card, you need to iterate it in the view and print the user for each card.
aaah i see, nonetheless i noticed that i turned it around. I need to get the user with it's cards, haha!
What you mentioned did work but it doesn't seem to 'associate' the right way around because i'm getting the error SQLite3::SQLException: no such column: cards.user_id: SELECT "cards".* FROM "cards" WHERE "cards"."user_id" = 1"". Shouldn't he query through cardlevels instead of cards?
Still got one(Hopefuly last for now) question, guys.
I've got the above data now and i can access my cards through users that are joined by the cardlevel. I'm trying to loop through all the cards a user has as such: <% @user.cards.each do |c| %> <%= c.name %><br> <% end %>
And this works great. However i'd like to get some extra info about this card from my cardlevel array, but i can't seem to access it like this. I can however loop it in a seperate each, but i don't want that obviously.
Any ideas?
Thanks
You have not explained well what you are trying to do, but possibly you want to loop through the cardlevels instead of the cards, then for each cardlevel you can obtain the card aswell as the other data, so something like
<% @user.cardlevels.each do |cl| %> <%= cl.card.name %><br> <%= cl.other_data %> <% end %>
You might need to check for cl.card nil though.
Colin
Colin Law wrote in post #1065311: