I have the following models: Users (id, name, email, instance_id, etc...) Instances (id, domain name) Books (id, name, user_id, instance_id)
In Rails 3, When a new book is created, I need the user_id, and instance_id to be populated based on the current_user.
Currently, user_id is being assigned when I create a new book but not instance_id? What needs to happen in rails to make that field get filled out on book creation?开发者_JS百科
Also, shouldn't rails be error'ing given that I can create books without that instance_id filled out?
thxs
It looks like you have de-normalized User
and Book
models by adding reference to Instance
model. You can avoid the redundant reference unless you have a specific reason.
I would rewrite your models as follows:
class Instance < ActiveRecord::Base
has_many :users
has_many :books, :through => :users, :order => "created_at DESC"
end
class User < ActiveRecord::Base
belongs_to :instance
has_many :books, :order => "created_at DESC"
end
class Book < ActiveRecord::Base
belongs_to :user
has_one :instance, :through => :user
end
Now to create a new book for a user.
current_user.books.build(...)
To get a list of the books belonging to user's instance:
current_user.instance.books
To get a list of the books created by the user:
current_user.books
Make sure you index the instance_id
column in users
table and user_id
column in books
table.
Rails will only produce an error in this case if (a) you have a validation that's failing, or (b) you have database foreign keys that aren't being satisfied.
What's an instance? i.e. if instance_id is to be populated based on the current user, what attribute of the user should supply it? (the instance_id? why?)
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