For example
class User < ActiveRecord::Base
has_one :avatar, :dependent => :destroy
end
class Avatar < ActiveRecord::Base
belongs_to :user
end
What if I have a User with an Avatar and then do something like
old_avatar = user.avatar
new_avatar = Avatar.new
user.avatar = new_avatar
user.save
old_avatar.destroy
So I don't want do the last command manually (destroy). Is there any options for has_many to autodestroy old object? Or many it's better use something else instead of avatar= method?
Thank you.
Why not update old avatar instead of creating new one like:
avatar = Avatar.find_or_initialize_by_user_id(:user_id => user.id)
avatar.attributes = new_attributes
avatar.save
Also, you might create after_save callback inside Avatar model if you like.
Related
I have the following model structure:
Model Visitor
class Visitor < ActiveRecord::Base
has_many: triggers
end
Model Trigger
class Trigger < ActiveRecord::Base
belongs_to :visitor, :inverse_of => :triggers
belongs_to :event, :inverse_of => :triggers
end
Model Event
class Event < ActiveRecord::Base
has_many: triggers
end
I am trying to setup a custom association in Visitor model like so:
has_many: triggers_that_pass_some_condition ,:class_name => "Trigger",
:conditions => ["triggers.some_column >= events.some_column"]
The problem is that it doesn't work .. I am guessing I have to do some kind of join to compare columns of two separate models (that are associated with each other)
I have tried
triggers.some_column >= triggers.event.some_column
That does not work either. Anyone has any suggestions? thanks!
Try the following code..
class Trigger < ActiveRecord::Base
belongs_to :event
belongs_to :visitor
end
# Visitors.rb
has_many :triggers_with_condition, -> { includes(:event).where(some_trigger_column >= event.some_event_column)}, class_name: "Trigger"
Make sure you first add the correct association between Visitor and Trigger in your model setup. From there, you can add a custom association as follows:
class Visitor < ActiveRecord::Base
has_many :approved_triggers, -> { includes(:events).where("events.something = ?", true).references(:events) }, class_name: 'Trigger', inverse_of: :visitor
end
class Trigger < ActiveRecord::Base
belongs_to :visitor, inverse_of :triggers
end
Right now your Trigger class holds no association to a Visitor.
Thanks to the clue from Darpa, I eventually settled on this:
has_many :custom_trigger, {:class_name => "Trigger", :include => :event,
:conditions => ["triggers.some_column >= events.another_column"]}
My model structure is as follows:
class Client < ActiveRecord::Base
has_many :charts
end
class Chart < ActiveRecord::Base
belongs_to :client
has_many :chart_data
end
class ChartDatum < ActiveRecord::Base
belongs_to :chart
end
ChartDatum has an attribute called 'name' which needs to be unique for each client.
I tried using "validates_uniqueness_of :name, :scope => [:chart_id]" but this helped me getting a unique key for a particular chart but not for all charts for a particular client. I am looking for something like "validates_uniqueness_of :name, :scope => [:client_id]" but obviously with the current structure it will not work out.
Could someone please help me?
Since you need unique name for chart_data for each client, you can try writing a custom validation for name something like this :
class ChartDatum < ActiveRecord::Base
belongs_to :chart
validates :name, :uniqueness => true, unless => :unique_for_client?
def unique_for_client?
client = self.chart.client
client.charts.chart_data.pluck(:name).include?(self.name)
end
end
I am currently building very simple Comment system on Rails. The primary models are User, Albumpost, and Comment. Users can post Albumposts. For each Albumpost, Users can add Comments to the Albumpost. As a result, a Comment belongs to a User and belongs to an Albumpost.
The problem I'm having is that even with the proper associations in my models (see below), I can't get
#comment.user.name
when I'm trying to render the comments in the albumpost 'show' page (/views/albumposts/show.html.erb). When I go to the page, I can't get #comment.user.name (doesn't understand the association) and get a
"undefined method `name' for nil:NilClass"
Oddly I can get
#comment.albumpost.content
I've double-checked my models and also added the proper foreign keys to the models. Am I doing something wrong in the controllers?
Here are my models:
class Comment < ActiveRecord::Base
attr_accessible :body, :albumpost_id, :user_id
belongs_to :albumpost
belongs_to :user
end
class Albumpost < ActiveRecord::Base
attr_accessible :content
belongs_to :user
has_many :comments, dependent: :destroy
end
class User < ActiveRecord::Base
attr_accessible :name, :email, :password, :password_confirmation
has_many :albumposts, dependent: :destroy
has_many :comments, dependent: :destroy
end
Here are the relevant parts of my Albumpost and Comments controllers:
class AlbumpostsController < ApplicationController
def show
#albumpost = Albumpost.find(params[:id])
#comments = #albumpost.comments
#comment = Comment.new
#comment.albumpost_id = #albumpost.id
#comment.user_id = current_user.id
end
end
class CommentsController < ApplicationController
def create
albumpost_id = params[:comment].delete(:albumpost_id)
#comment = Comment.new(params[:comment])
#comment.albumpost_id = albumpost_id
#comment.user_id = current_user.id
#comment.save
redirect_to albumpost_path(#comment.albumpost)
end
end
I think you should prefer setting objects to relations instead of setting their ids. For example, you should do this:
#comment.user = current_user
instead of
#comment.user_id = current_user.id
ActiveRecord will take care of setting corresponding *_id fields. I'm not sure how it handles the reverse. (it should autoload though, if I understand correctly)
I have a User model:
class User < ActiveRecord::Base
has_many :cards
end
and a Card model:
class Card< ActiveRecord::Base
belongs_to :user, :foreign_key => "owner_id"
end
the card model also has an attribute called "owner_id", which I'd like to use in way like this:
Card.first.owner which will retrieve the User which owns that card
my problem as that, I know that rails will automagically connect the id's in the association but that doesnt happen.
in the CardController, rails get stuck in the create action on the line
#card=current_user.cards.new(params[:card])
and says unknown attribute: user_id
I've done db:migrate and it still won't work.
must I do as follows for it to work?
#card = Card.new(params[:card])
#card.owner_id=current_user.id
or am I missing something?
First of all, you don't need a owner_id column for this. All you need is
class User
has_many :cards
end
This will give you #user.cards
class Card
belongs_to :owner, :class_name => "User", :foreign_key => "user_id"
end
This will give you #card.owner
I have the following:
class Org < ActiveRecord::Base
has_many :users
has_many :entries
end
class Entry < ActiveRecord::Base
belongs_to :org
belongs_to :user
validates_presence_of :entry_text
end
class User < ActiveRecord::Base
belongs_to :org
has_many :entries
validates_uniqueness_of :user_name
validates_presence_of :user_name, :length => { :minimum => 3 }
end
I can Create Orgs and Users... How do i create an entry if there are two belongs_to? and what is this pattern called?
Double nested resources are tricky. The trick with users usually is to keep it out of your desired entry path.
Your question is kind of broad, but if you specify more information, people would be able to help you better. Also, I would recommend using the gem Devise for your user management system. Since you're using 'users' I would assume you want users from orgs to create entries. The entry created would be a part of org and the user would be the session's current user. Sorry if I am wrong to assume this.
Your routes.rb file can look something like this (assuming rails 3):
resources :orgs do
resources :entries
end
Then the create of your entry controller would look like:
#entry = #org.entries.new(params[:topic])
#entry.user = current_user #or however you are managing the current user's session.
And you'd want to set the org for the entire class by making a method that loads your current org and do a before_filter :loadOrg
def loadOrg
#org = Org.find(params[:id])
end
This is of course assuming your path is something like: /org/(id)/entry/(entry_id)
and not
/org/(id)/user/(user_id)/entry/(entry_id)
which in my opinion is unnecessary and can lead to more problems. You can always create a userpage model that calls all entries by users, but the default route doesn't necessarily have to include users in the path.
I don't see any problem.
#entry = Entry.create(:entry_text => "Hello World!")
Now questions to clarify what do you need:
Can #entry belongs both org and user at the same time? Or it can belongs to only one of them?
Should #entry belongs to at least one of them?
If #entry supposed to belong only one of them, so you should use Polymorphism
http://railscasts.com/episodes/154-polymorphic-association
class Entry < ActiveRecord::Base
belongs_to :textable, :polymorphic => true
validates_presence_of :entry_text
end
class Org < ActiveRecord::Base
has_many :users
has_many :entries, :as => :textable
end
class User < ActiveRecord::Base
belongs_to :org
has_many :entries, :as => :textable
validates_uniqueness_of :user_name
validates_presence_of :user_name, :length => { :minimum => 3 }
end