Is there a way to get embedded documents to initialize automatically on construction in mongoid? What I mean is given that User which embeds a garage document. I have to write the following code to fully set up the user with the garage:
user = User.create!(name: "John")
user.build_garage
user.garage.cars << Car.create!(name: "Bessy")
Is there a way I can skip calling user.build_garage?
Thanks
Mongoid 3 have autobuild option which tells Mongoid to instantiate a new document when the relation is accessed and it is nil.
embeds_one :label, autobuild: true
has_one :producer, autobuild: true
You can add a callback to the User model like this:
class User
...
after_initialize do |u|
u.build_garage unless u.garage
end
...
end
This callback fires after each instantiation of the class, so it fires after 'find' and 'new'.
Related
i have a special case for which i need to know the best practice.
Given a simple has_many association:
class Authentication < ActiveRecord::Base
belongs_to :user
#provider can be :password, :facebook_oauth etc
#code is the encrypted password on provider == :password
end
class User < ActiveRecord::Base
has_many :authentications
#this works
def encrypted_password=(pw)
set = false
self.authentications.each do |auth|
if auth.provider.to_sym == :password
set = true
auth.code = pw
end
end
self.authentications.build(provider: :password, code: pw) unless set
pw
end
#this only when no password-auth exist yet
def encrypted_password=(pw)
self.authentications.find_or_initialize_by(provider: :password).code = pw
end
end
and then
user = User.last
user.password="abcdefg"
user.save
While the first solution works, it loads and iterates over ALL associated Authentication objects. It was a workaround but this is a no-go.
The second solution does not work when it loads an existing Password-Authentication object. The User object does not know about the change on the Authentication object loaded with the find_or_initialize_by method. The change won't be saved...
Is there a way to register the changed Authentication object back to the User object so that it will be autosaved when called user.save?
It seems saving associating object returned with find back to parent object is impossible as of now. Refer to this issue https://github.com/rails/rails/issues/17466.
I had the same issue, and my workaround was, even though this is not you nor I wanted, to use save in the method yourself and make all the saves inside the transaction.
def encrypted_password=(pw)
self.authentications.find_or_initialize_by(provider: :password).update_attribute(code, pw)
end
Is there a way to register the changed Authentication object back to the User object so that it will be autosaved when called user.save?
If your question only consists of needing to know how to save an associated class, you can add this to your class definition:
class User < ActiveRecord::Base
has_many :authentications, autosave: true
end
The Authentication object is already referenced back to the User object via the user_id column that should be on Authentication by way of the belongs_to method. This autosave: true will save the associated object Authentication when the parent object (User) is saved.
I've been following the Getting Started rails tutorial and am now trying some custom functionality.
I have 2 models, Person and Hangout. A Person can have many Hangouts. When creating a Hangout, a Person has to be selected and associated with the new Hangout. I'm running into issues however when I call my create action. This fires before the validate_presence_of for person.
Am I going about this the wrong way? Seems like I shouldn't have to create a custom before_create validation to make sure that a Hangout was created with a Person.
#hangout_controller
def create
#person = Person.find(params[:hangout][:person_id])
#hangout = #person.hangouts.create(hangout_params)
#hangout.save
redirect_to hangouts_path(#hangout)
end
#hangout.rb
class Hangout < ActiveRecord::Base
belongs_to :person
validates_presence_of :person
end
#person.rb
class Person < ActiveRecord::Base
has_many :hangouts
validates :first_name, presence: true
validates :met_location, presence: true
validates :last_contacted, presence: true
def full_name
"#{first_name} #{last_name}"
end
end
Create action fires before the validate_presence_of for person
I think you are confused about rails MVC. Your form contains a url and when you submit your form your form params are send to your controller action according to the routes you have defined in routes.rb Your controller action, in this case create action, interacts with model this is very it checks for your validations and if all the validations are passed your object is saved in databse so even though in your app the control is first passed to your controller but your object is saved only once if all the validations are passed.
Now lets comeback to your code. There are couple of things you are doing wrong
a. You don't need to associate your person separately:
In your create action you have this line:
#person = Person.find(params[:hangout][:person_id])
You don't need to do this because your person_id is already coming from your form and it'll automatically associate your hangout with person.
b. You are calling create method instead of build:
When you call .association.create method it does two things for you it first initialize your object, in your case your hangout and if all the validations are passed it saves it. If all the validations are not passed it simply rollback your query.
If you'll use .association.build it'll only initialize your object with the params coming from your form
c. Validation errors won't show:
As explained above, since you are calling create method instead of build your validation error won't show up.
Fix
Your create method should look like this:
def create
#hangout = Hangout.new(hangout_params) # since your person_id is coming from form it'll automatically associate your new hangout with person
if #hangout.save
redirect_to hangouts_path(#hangout)
else
render "new" # this will show up validation errors in your form if your hangout is not saved in database
end
end
private
def hangout_params
params.require(:hangout).permit(:person_id, :other_attributes)
end
You are confused with the controller and model responsibilities.
Let me try to explain what I think is confusing you:
First try this in your rails console:
Hangout.create
It shouldn't let you because you are not passing a Person object to the create method. So, we confirm that the validation is working fine. That validation means that before creating a Hangout, make sure that there is a person attribute. All this is at the model level, nothing about controllers yet!
Let's go to the controllers part. When the create action of the controller 'is fired', that controller doesn't know what you are trying to do at all. It doesn't run any validations. It is just an action, that if you want, can call the Hangout model to create one of those.
I believe that when you say 'it fires' you are saying that the create action of the HangoutController is called first than the create method on the Hangout model. And that is completely fine. The validations run at the model level.
Nested Attributes
I think you'll be better using accepts_nested_attributes_for - we've achieved functionality you're seeking before by using validation on the nested model (although you'll be able to get away with using reject_if: :all_blank):
#app/models/person.rb
Class Person < ActiveRecord::Base
has_many :hangouts
accepts_nested_attributes_for :hangouts, reject_if: :all_blank
end
#app/models/hangout.rb
Class Hangout < ActiveRecord::Base
belongs_to :person
end
This will give you the ability to call the reject_if: :all_blank method -
Passing :all_blank instead of a Proc will create a proc that will
reject a record where all the attributes are blank excluding any value
for _destroy.
--
This means you'll be able to create the following:
#config/routes.rb
resources :people do
resources :hangouts # -> domain.com/people/:people_id/hangouts/new
end
#app/controllers/hangouts_controller.rb
Class HangoutsController < ApplicationController
def new
#person = Person.find params[:people_id]
#hangout = #person.hangouts.build
end
def create
#person = Person.find params[:people_id]
#person.update(hangout_attributes)
end
private
def hangout_attributes
params.require(:person).permit(hangouts_attributes: [:hangout, :attributes])
end
end
Although I've not tested the above, I believe this is the way you should handle it. This will basically save the Hangout associated object for a particular Person - allowing you to reject if the Hangout associated object is blank
The views would be as follows:
#app/views/hangouts/new.html.erb
<%= form_for [#person, #hangout] do |f| %>
<%= f.fields_for :hangouts do |h| %>
<%= h.text_field :name %>
<% end %>
<%= f.submit %>
<% end %>
I have a 1-n relationship defined as follows:
class User
field :email, type: String
embeds_many :papers
end
class Paper
embedded_in :user
end
If I try and access the parent fields (user) from the child (paper) like so:
User.all.map(:papers).flatten.first.user.email
Then I get nil :(
Accessing like this works fine though:
User.all.first.papers.first.user.email
It's a mispelling lire report on comment. To call a method on a map,you need use & before your symbol.
Try:
User.all.map(&:papers).flatten.first.user.email
Is there a way to run a callback only if an embedded document field was changed?
Currently, the following runs the callback on a normal field only if it was changed:
class user
field :email, type: String
embeds_many :connections, cascade_callbacks: true
before_save :run_callback, :if => :email_changed?
before_save :run_connection_callback, :if => :connections_changed? # DOES NOT WORK
end
For anybody seeing this answer in 2015
In Mongoid 4.x model.changed? and model.changes exist and behave like their ActiveRecord counterparts.
Mongoid won't define the method connections_changed? for you, but you can define it yourself by using a virtual field in User to keep track of when an embedded connection gets changed. That is:
class User
# define reader/writer methods for #connections_changed
attr_accessor :connections_changed
def connections_changed?
self.connections_changed
end
# the connections are no longer considered changed after the persistence action
after_save { self.connections_changed = false }
before_save :run_connection_callback, :if => :connections_changed?
end
class Connection
embedded_in :user
before_save :tell_user_about_change, :if => :changed?
def tell_user_about_change
user.connections_changed = true
end
end
One shortcoming of this method is that user.connections_changed only gets set when the document is saved. The callbacks are cascaded in such a way that the Connection before_save callback gets called first and then the User before save callback, which allows the above code to work for this use case. But if you need to know whether any connections have changed before calling save, you'll need to find another method.
I was wondering if there was a way to trigger the after_save callback on an embedded_in object in Mongoid mapper.
Example:
i = Image.new(:file => file)
user.images << i
# => i.after_save should be triggered here
I'm aware that if I call i.save after words, it will fire, however really hard to remember to do that throughout my code.
Also, calling user.images.create(:file => file) is not an option, because I do a check to make sure the same file isn't uploaded twice.
Okay, this is an old question, but with latest Mongoid, you can use:
http://mongoid.org/en/mongoid/docs/relations.html
Cascading Callbacks
If you want the embedded document callbacks to fire when calling a persistence operation on its parent, you will need to provide the cascade callbacks option to the relation.
Cascading callbacks is only available on embeds_one and embeds_many relations.
class Band
include Mongoid::Document
embeds_many :albums, cascade_callbacks: true
embeds_one :label, cascade_callbacks: true
end
band.save # Fires all save callbacks on the band, albums, and label.
The only real solution is to call save on the embedded document. Here's a way to have that done automatically:
class User
references_many :images do
def <<(new_elm)
returner = super
new_elm.save
returner
end
end
end
More info here:
https://github.com/mongoid/mongoid/issues/173