I have two models - Customer and Contractors. I have setup a simple app, where they interact on an activity. Now at the end of it, I would like for them to leave each other feedbacks. Nothing complex just a database field of comment.
I am wondering what is the right model association to have here?
I tried this
class Customer
has_many :feedbacks
end
class Contractor
has_many :feedbacks
end
class Feedback
belongs_to :customer
belongs_to :contractor
end
But the problem here is identifying who commented who.
For instance, if I do
customer = Customer.find(1)
contractor = Contractor.find(1)
customer.feedbacks.create(:comment => "Contractor 1 sucks", :contractor_id => 1)
The problem is, its accessible by both contractor.feedbacks and customer.feedbacks. And I dont know who commented who now.
Any guidance is appreciated. Am i missing something?
Thanks
The way to do this would be to use polymorphic associations.
This way, you could have a commenter relationship, and a commentable relationship.
Like so:
class Customer
has_many :feedbacks, as: commenter
has_many :feedbacks, as: commentable
end
class Contractor
has_many :feedbacks, as: commenter
has_many :feedbacks, as: commentable
end
class Feedback
belongs_to :commenter, polymorphic: true
belongs_to :commentable, polymorphic: true
end
Now, Feedback will require four new columns:
commentable_type:string
commentable_id:integer
commenter_type:string
commenter_id:integer
All four should be indexed, so write your migrations appropriately. The type columns will store a String value of the model name associated ("Customer" or "Contractor").
So you can do things like:
#feedback = Feedback.find 3
#feedback.commenter
=> # Some Customer
#feedback.commentable
=> # Some Contractor
And vise versa. You would build like:
#customer = Customer.find 1
#contractor = Contractor.find 1
#feedback = Feedback.new comment: "This is a great Contractor"
#feedback.commenter = #customer # You can reverse this for a contractor giving feedback to a customer
#feedback.commentable = #contractor
#feedback.save!
Related
I have the following models.
class Company < ApplicationRecord
has_many :company_users
has_many :users, :through => :company_users
after_update :do_something
private
def do_something
# check if users of the company have been updated here
end
end
class User < ApplicationRecord
has_many :company_users
has_many :companies, :through => :company_users
end
class CompanyUser < ApplicationRecord
belongs_to :company
belongs_to :user
end
Then I have these for the seeds:
Company.create :name => 'Company 1'
User.create [{:name => 'User1'}, {:name => 'User2'}, {:name => 'User3'}, {:name => 'User4'}]
Let's say I want to update Company 1 users, I will do the following:
Company.first.update :users => [User.first, User.second]
This will run as expected and will create 2 new records on CompanyUser model.
But what if I want to update again? Like running the following:
Company.first.update :users => [User.third, User.fourth]
This will destroy the first 2 records and will create another 2 records on CompanyUser model.
The thing is I have technically "updated" the Company model so how can I detect these changes using after_update method on Company model?
However, updating an attribute works just fine:
Company.first.update :name => 'New Company Name'
How can I make it work on associations too?
So far I have tried the following but no avail:
https://coderwall.com/p/xvpafa/rails-check-if-has_many-changed
Rails: if has_many relationship changed
Detecting changes in a rails has_many :through relationship
How to determine if association changed in ActiveRecord?
Rails 3 has_many changed?
There is a collection callbacks before_add, after_add on has_many relation.
class Project
has_many :developers, after_add: :evaluate_velocity
def evaluate_velocity(developer)
#non persisted developer
...
end
end
For more details: https://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html#label-Association+callbacks
You can use attr_accessor for this and check if it changed.
class Company < ApplicationRecord
attr_accessor :user_ids_attribute
has_many :company_users
has_many :users, through: :company_users
after_initialize :assign_attribute
after_update :check_users
private
def assign_attribute
self.user_ids_attribute = user_ids
end
def check_users
old_value = user_ids_attribute
assign_attribute
puts 'Association was changed' unless old_value == user_ids_attribute
end
end
Now after association changed you will see message in console.
You can change puts to any other method.
I have the feelings you are asking the wrong question, because you can't update your association without destroy current associations. As you said:
This will destroy the first 2 records and will create another 2 records on CompanyUser model.
Knowing that I will advice you to try the following code:
Company.first.users << User.third
In this way you will not override current associations.
If you want to add multiple records once try wrap them by [ ] Or ( ) not really sure which one to use.
You could find documentation here : https://guides.rubyonrails.org/association_basics.html#has-many-association-reference
Hope it will be helpful.
Edit:
Ok I thought it wasn't your real issue.
Maybe 2 solutions:
#1 Observer:
what I do it's an observer on your join table that have the responsability to "ping" your Company model each time a CompanyUser is changed.
gem rails-observers
Inside this observer call a service or whatever you like that will do what you want to do with the values
class CompanyUserObserver < ActiveRecord::Observer
def after_save(company_user)
user = company_user.user
company = company_user.company
...do what you want
end
def before_destroy(company_user)
...do what you want
end
end
You can user multiple callback in according your needs.
#2 Keep records:
It turn out what you need it keep records. Maybe you should considerate use a gem like PaperTrail or Audited to keep track of your changes.
Sorry for the confusion.
Let's say you have the following models:
class User < ActiveRecord::Base
has_many :comments, :as => :author
end
class Comment < ActiveRecord::Base
belongs_to :user
end
Let's say User has an attribute name, is there any way in Ruby/Rails to access it using the table name and column, similar to what you enter in a select or where query?
Something like:
Comment.includes(:author).first.send("users.name")
# or
Comment.first.send("comments.id")
Edit: What I'm trying to achieve is accessing a model object's attribute using a string. For simple cases I can just use object.send attribute_name but this does not work when accessing "nested" attributes such as Comment.author.name.
Basically I want to retrieve model attributes using the sql-like syntax used by ActiveRecord in the where() and select() methods, so for example:
c = Comment.first
c.select("users.name") # should return the same as c.author.name
Edit 2: Even more precisely, I want to solve the following problem:
obj = ANY_MODEL_OBJECT_HERE
# Extract the given columns from the object
columns = ["comments.id", "users.name"]
I don't really understand what you are trying to achieve. I see that you are using polymorphic associations, do you need to access comment.user.name while having has_many :comments, :as => :author in your User model?
For you polymorphic association, you should have
class Comment < ActiveRecord::Base
belongs_to :author, :polymorphic => true
end
And if you want to access comment.user.name, you can also have
class Comment < ActiveRecord::Base
belongs_to :author, :polymorphic => true
belongs_to :user
end
class User < ActiveRecord::Base
has_many :comments, :as => :author
has_many :comments
end
Please be more specific about your goal.
I think you're looking for a way to access the user from a comment.
Let #comment be the first comment:
#comment = Comment.first
To access the author, you just have to type #comment.user and If you need the name of that user you would do #comment.user.name. It's just OOP.
If you need the id of that comment, you would do #comment.id
Because user and id are just methods, you can call them like that:
comments.send('user').send('id')
Or, you can build your query anyway you like:
Comment.includes(:users).where("#{User::columns[1]} = ?", #some_name)
But it seems like you're not doing thinks really Rails Way. I guess you have your reasons.
I have a has_many through association setup between a song model and an artist model.
My code looks something like this
SongArtistMap Model
class SongArtistMap < ActiveRecord::Base
belongs_to :song
belongs_to :artist
end
Artist Model
class Artist < ActiveRecord::Base
has_many :song_artist_maps
has_many :songs, :through => :song_artist_maps
validates_presence_of :name
end
Song Model
class Song < ActiveRecord::Base
has_many :song_artist_maps
has_many :artists, :through => :song_artist_maps
accepts_nested_attributes_for :artists
end
I have a form where a user submits a song and enters in the song title and the song artist.
So when a user submits a song and my Artists table doesn't already have the artist for the song I want it to create that artist and setup the map in SongArtistMap
If a user submits a song with an artist that is already in the Artists table I just want the SongArtistMap created but the artist not duplicated.
Currently everytime a user submits a song a new artist gets created in my artists table even if the same one already exists and a SongArtistMap is created for that duplicated artist.
Any idea on how to tackle this issue? I feel like rails probably has some easy little trick to fix this already built in. Thanks!
Ok I got this figured out awhile ago and forgot to post. So here's how I fixed my problem. First of all I realized I didn't need to have a has_many through relationship.
What I really needed was a has_and_belongs_to_many relationship. I setup that up and made the table for it.
Then in my Artists model I added this
def self.find_or_create_by_name(name)
k = self.find_by_name(name)
if k.nil?
k = self.new(:name => name)
end
return k
end
And in my Song model I added this
before_save :get_artists
def get_artists
self.artists.map! do |artist|
Artist.find_or_create_by_name(artist.name)
end
end
And that did exactly what I wanted.
I use a method in the model of the table the other two go through, that is called with before_create. This can probably be made much neater and faster though.
before_create :ensure_only_one_instance_of_a_user_in_a_group
private
def ensure_only_one_instance_of_a_user_in_a_group
user = User.find_by_id(self.user_id)
unless user.groups.empty?
user.groups.each do |g|
if g.id == self.group_id
return false
end
end
end
return true
end
Try this:
class Song < ActiveRecord::Base
has_many :song_artist_maps
has_many :artists, :through => :song_artist_maps
accepts_nested_attributes_for :artists, :reject_if => :normalize_artist
def normalize_artist(artist)
return true if artist['name'].blank?
artist['id'] = Artist.find_or_create_by_name(artist['name']).id
false # This is needed
end
end
We are essentially tricking rails by over-loading the reject_if function(as we never return true).
You can further optimize this by doing case insensitive lookup ( not required if you are on MySQL)
artist['id'] = (
Artist.where("LOWER(name) = ? ", artist['name'].downcase).first ||
Artist.create(:name => artist['name'])
).id
I'm using Rails' accepts_nested_attributes_for method with great success, but how can I have it not create new records if a record already exists?
By way of example:
Say I've got three models, Team, Membership, and Player, and each team has_many players through memberships, and players can belong to many teams. The Team model might then accept nested attributes for players, but that means that each player submitted through the combined team+player(s) form will be created as a new player record.
How should I go about doing things if I want to only create a new player record this way if there isn't already a player with the same name? If there is a player with the same name, no new player records should be created, but instead the correct player should be found and associated with the new team record.
When you define a hook for autosave associations, the normal code path is skipped and your method is called instead. Thus, you can do this:
class Post < ActiveRecord::Base
belongs_to :author, :autosave => true
accepts_nested_attributes_for :author
# If you need to validate the associated record, you can add a method like this:
# validate_associated_record_for_author
def autosave_associated_records_for_author
# Find or create the author by name
if new_author = Author.find_by_name(author.name)
self.author = new_author
else
self.author.save!
end
end
end
This code is untested, but it should be pretty much what you need.
Don't think of it as adding players to teams, think of it as adding memberships to teams. The form doesn't work with the players directly. The Membership model can have a player_name virtual attribute. Behind the scenes this can either look up a player or create one.
class Membership < ActiveRecord::Base
def player_name
player && player.name
end
def player_name=(name)
self.player = Player.find_or_create_by_name(name) unless name.blank?
end
end
And then just add a player_name text field to any Membership form builder.
<%= f.text_field :player_name %>
This way it is not specific to accepts_nested_attributes_for and can be used in any membership form.
Note: With this technique the Player model is created before validation happens. If you don't want this effect then store the player in an instance variable and then save it in a before_save callback.
A before_validation hook is a good choice: it's a standard mechanism resulting in simpler code than overriding the more obscure autosave_associated_records_for_*.
class Quux < ActiveRecord::Base
has_and_belongs_to_many :foos
accepts_nested_attributes_for :foos, reject_if: ->(object){ object[:value].blank? }
before_validation :find_foos
def find_foos
self.foos = self.foos.map do |object|
Foo.where(value: object.value).first_or_initialize
end
end
end
When using :accepts_nested_attributes_for, submitting the id of an existing record will cause ActiveRecord to update the existing record instead of creating a new record. I'm not sure what your markup is like, but try something roughly like this:
<%= text_field_tag "team[player][name]", current_player.name %>
<%= hidden_field_tag "team[player][id]", current_player.id if current_player %>
The Player name will be updated if the id is supplied, but created otherwise.
The approach of defining autosave_associated_record_for_ method is very interesting. I'll certainly use that! However, consider this simpler solution as well.
Just to round things out in terms of the question (refers to find_or_create), the if block in Francois' answer could be rephrased as:
self.author = Author.find_or_create_by_name(author.name) unless author.name.blank?
self.author.save!
This works great if you have a has_one or belongs_to relationship. But fell short with a has_many or has_many through.
I have a tagging system that utilizes a has_many :through relationship. Neither of the solutions here got me where I needed to go so I came up with a solution that may help others. This has been tested on Rails 3.2.
Setup
Here are a basic version of my Models:
Location Object:
class Location < ActiveRecord::Base
has_many :city_taggables, :as => :city_taggable, :dependent => :destroy
has_many :city_tags, :through => :city_taggables
accepts_nested_attributes_for :city_tags, :reject_if => :all_blank, allow_destroy: true
end
Tag Objects
class CityTaggable < ActiveRecord::Base
belongs_to :city_tag
belongs_to :city_taggable, :polymorphic => true
end
class CityTag < ActiveRecord::Base
has_many :city_taggables, :dependent => :destroy
has_many :ads, :through => :city_taggables
end
Solution
I did indeed override the autosave_associated_recored_for method as follows:
class Location < ActiveRecord::Base
private
def autosave_associated_records_for_city_tags
tags =[]
#For Each Tag
city_tags.each do |tag|
#Destroy Tag if set to _destroy
if tag._destroy
#remove tag from object don't destroy the tag
self.city_tags.delete(tag)
next
end
#Check if the tag we are saving is new (no ID passed)
if tag.new_record?
#Find existing tag or use new tag if not found
tag = CityTag.find_by_label(tag.label) || CityTag.create(label: tag.label)
else
#If tag being saved has an ID then it exists we want to see if the label has changed
#We find the record and compare explicitly, this saves us when we are removing tags.
existing = CityTag.find_by_id(tag.id)
if existing
#Tag labels are different so we want to find or create a new tag (rather than updating the exiting tag label)
if tag.label != existing.label
self.city_tags.delete(tag)
tag = CityTag.find_by_label(tag.label) || CityTag.create(label: tag.label)
end
else
#Looks like we are removing the tag and need to delete it from this object
self.city_tags.delete(tag)
next
end
end
tags << tag
end
#Iterate through tags and add to my Location unless they are already associated.
tags.each do |tag|
unless tag.in? self.city_tags
self.city_tags << tag
end
end
end
The above implementation saves, deletes and changes tags the way I needed when using fields_for in a nested form. I'm open to feedback if there are ways to simplify. It is important to point out that I am explicitly changing tags when the label changes rather than updating the tag label.
Answer by #François Beausoleil is awesome and solved a big problem. Great to learn about the concept of autosave_associated_record_for.
However, I found one corner case in this implementation. In case of update of existing post's author(A1), if a new author name(A2) is passed, it will end up changing the original(A1) author's name.
p = Post.first
p.author #<Author id: 1, name: 'JK Rowling'>
# now edit is triggered, and new author(non existing) is passed(e.g: Cal Newport).
p.author #<Author id: 1, name: 'Cal Newport'>
Oringinal code:
class Post < ActiveRecord::Base
belongs_to :author, :autosave => true
accepts_nested_attributes_for :author
# If you need to validate the associated record, you can add a method like this:
# validate_associated_record_for_author
def autosave_associated_records_for_author
# Find or create the author by name
if new_author = Author.find_by_name(author.name)
self.author = new_author
else
self.author.save!
end
end
end
It is because, in case of edit, self.author for post will already be an author with id:1, it will go in else, block and will update that author instead of creating new one.
I changed the code(elsif condition) to mitigate this issue:
class Post < ActiveRecord::Base
belongs_to :author, :autosave => true
accepts_nested_attributes_for :author
# If you need to validate the associated record, you can add a method like this:
# validate_associated_record_for_author
def autosave_associated_records_for_author
# Find or create the author by name
if new_author = Author.find_by_name(author.name)
self.author = new_author
elsif author && author.persisted? && author.changed?
# New condition: if author is already allocated to post, but is changed, create a new author.
self.author = Author.new(name: author.name)
else
# else create a new author
self.author.save!
end
end
end
#dustin-m's answer was instrumental for me - I am doing something custom with a has_many :through relationship. I have a Topic which has one Trend, which has many children (recursive).
ActiveRecord does not like it when I configure this as a standard has_many :searches, through: trend, source: :children relationship. It retrieves topic.trend and topic.searches but won't do topic.searches.create(name: foo).
So I used the above to construct a custom autosave and am achieving the correct result with accepts_nested_attributes_for :searches, allow_destroy: true
def autosave_associated_records_for_searches
searches.each do | s |
if s._destroy
self.trend.children.delete(s)
elsif s.new_record?
self.trend.children << s
else
s.save
end
end
end
I have two Models: Campaign and Contact.
A Campaign has_many Contacts.
A Contact has_many Campaigns.
Currently, each Contact has a contact.date_entered attribute. A Campaign uses that date as the ate to count down to the different Events that belong_to the Campaign.
However, there are situations where a Campaign for a specific Contact may need to be delayed by X number of days. In this instance, the campaigncontact.delaydays = 10.
In some cases, the Campaign must be stopped altogether for the specific Contact, so for now I set campaigncontact.delaydays = 1. (Are there major problems with that?)
By default, I am assuming that no campaigncontact exists (but not sure how that works?)
So here's what I've tried to do:
class Contact < ActiveRecord::Base
has_many :campaigncontacts
has_many :campaigns, :through => :campaigncontacts
end
class Campaign < ActiveRecord::Base
has_many :campaigncontacts
has_many :contacts, :through => :campaigncontacts
end
script/generate model campaigncontact campaign_id:integer contact_id:integer delaydays:integer
class Campaigncontact < ActiveRecord::Base
belongs_to :campaign
belongs_to :contact
end
So, here's the question: Is the above correct? If so, how do I allow a user to edit the delay of a campaign for a specific Contact.
For now, I want to do so from the Contact View.
This is what I tried:
In the Contact controller (?)
in_place_edit_for :campaigncontact, column.delaydays
And in the View
<%= in_place_editor_field :campaigncontact, :delaydays %>
How can I get it right?
I would add an integer field to your Campaigncontacts resource called days_to_delay_communication_by, since this information relates to the association of a campaign and a contact rather than a contact itself.
in your migration:
def self.up
add_column(:campaigncontacts, :days_to_delay_communication_by, :integer)
end
def self.down
remove_column(:campaigncontacts, :days_to_delay_communication_by)
end
Now you can set that value by:
campaigncontact = Campaigncontacts.find(:first, :conditions => { :campaign_id => campaign_id, :contact_id => contact_id })
campaigncontact.days_to_delay_communication_by = 10
Then in the admin side of your application you can have a controller and a view for campaign communications that lets you set the days_to_delay_communication_by field for campaigncontacts. I can expand on this further for you if you're interested, but I think you get the idea.
Then you'll need to run a background process of some sort (probably a cron job, or use the delayed_job plugin), to find communications that haven't happened yet, and make them happen when the date has passed. You could do this in a rake task like so:
namespace :communications do
namespace :monitor do
desc 'Monitor and send communications for campaigns'
task :erma => :environment do
Rails.logger.info "-----BEGIN COMMUNICATION MONITORING-----"
unsent_communications = Communication.all(:conditions => { :date_sent => nil})
unsent_communications.each do |communication|
Rails.logger.info "**sending communication**"
communication.send if communication.time_to_send < Time.now
Rails.logger.info "**communication sent**"
end
Rails.logger.info "-----END COMMUNICATION MONITORING-----"
end #end erma task
end #end sync namespace
end #end db namespace
Then your cron job would do something like:
cd /path/to/application && rake communications:monitor RAILS_ENV=production
Also, I'd consider changing the name of your join model to something more descriptive of it's purpose, for instance memberships, a campaign has many memberships and a contact has many memberships. Then a membership has a days_to_delay_communication field.
A good way to do this is use a "fake" attribute on your Contact model like so:
class Contact < ActiveRecord::Base
has_many :campaigncontacts
has_many :campaigns, :through => :campaigncontacts
attr_accessor :delay
def delay #edit
self.campaigncontacts.last.delaydays
end
def delay=(val)
self.campaigncontacts.each do |c|
c.delaydays = val
end
end
end
Then just set the in_place_editor for this fake field:
in_place_edit_for :contact, :delay
and
<%= in_place_editor_field :contact, :delay %>
I'm not sure I understood exactly what you wanted to accomplish, but I hope this at least points you into the right direction.