Please tell me the way how to implement dynamic associative link, which is itself determined by the attribute model.
I have two engines(Tbitcoin, Tstripe) each of them have a table payment. The model User has pay_currency attribute, which is the managing.
class User < ActiveRecord::Base
has_many :payments, ~> { where "pay_currency = 'real'" } , class_name: Tstripe::Payment, foreign_key: :uid
has_many :payments, ~> { where "pay_currency = 'bitcoin'" } ,class_name: Tbitcoin::Payment, foreign_key: :uid
end
What are the ways to dynamically determine the engine using User.last.payments.create ?
I think that you need a regular method instead of has_many association which will find proper payments associated with the user according to pay_currency value. Example:
class User < ActiveRecord::Base
def payments
payment_class = case pay_currency
when "real"
Tstripe::Payment
when "bitcoin"
Tbitcoin::Payment
end
payment_class.for_user(self)
end
end
class Tstripe::Payment < ActiveRecord::Base
belongs_to :user
def self.for_user(user)
where(user_id: user.uid)
end
end
I'm new to Rails and ActiveRecord and need some help. Basically, I have 4 models: User, Property, PropertyAccount, and AccountInvitation. Users and Properties have a many to many relationship via PropertyAccounts. AccountInvitations have a user's email and a property_id.
What I want to happen is that after a user registers on my app, his user account is automatically associated with some pre-created Properties. What I don't know how to do is write the query to get the Property objects from the AccountInvitations and save them to the User object. Please see def assign_properties for my pseudo code. Any help is welcome, thanks so much!
class User < ActiveRecord::Base
has_many :property_accounts
has_many :properties, through: :property_accounts
after_create :assign_properties
# Check to see if user has any pre-assigned properties, and if so assign them
def assign_properties
account_invitations = AccountInvitations.where(email: self.email)
if account_invitations.any?
account_invitations.each do |i|
properties += Property.find(i.property_id)
end
self.properties = properties
self.save
end
end
end
class AccountInvitation < ActiveRecord::Base
belongs_to :property
validates :property_id, presence: true
validates :email, uniqueness: {scope: :property_id}
end
class Property < ActiveRecord::Base
has_many :account_invitations
has_many :property_accounts
has_many :users, through: :property_accounts
end
class PropertyAccount < ActiveRecord::Base
belongs_to :property
belongs_to :user
end
Thanks to #wangthony , I looked at the includes method on http://apidock.com/rails/ActiveRecord/QueryMethods/includes and tweaked one of their examples in order to get this to work. Here's the solution:
def assign_property
self.properties = Property.includes(:account_invitations).where('account_invitations.email = ?', self.email).references(:account_invitations)
self.save
end
I believe you can do this:
user.properties = Property.includes(:account_invitations).where(email: user.email)
user.save
I have a model:
class Delivery < ActiveRecord::Base
has_and_belongs_to_many :dropoff_points, :join_table => :delivery_dropoff_points
end
This model has a field scheduled_date.
This is a DeliveryDropoffPoint class:
class DeliveryDropoffPoint < ActiveRecord::Base
belongs_to :delivery
belongs_to :dropoff_point
end
I need to make sure that when I create a record in rails-admin on any given day the dropoff point gets one and only one delivery.
I tried to implement before_save filter:
class DeliveryDropoffPoint < ActiveRecord::Base
belongs_to :delivery
belongs_to :dropoff_point
def set_scheduled_date
self.scheduled_date = delivery.scheduled_date
end
before_save :set_scheduled_date
validates_uniqueness_of :branch_floor, :scope => :scheduled_date, :message => "floor can only have one job assigned on a given day"
end
However, rails-admin seemed to ignore it, regretfully. Is there any other way to set the value of a column in a join table when selecting the items in the select-box in rails-admin?
Thanks!
I want to be able to use two columns on one table to define a relationship. So using a task app as an example.
Attempt 1:
class User < ActiveRecord::Base
has_many :tasks
end
class Task < ActiveRecord::Base
belongs_to :owner, class_name: "User", foreign_key: "owner_id"
belongs_to :assignee, class_name: "User", foreign_key: "assignee_id"
end
So then Task.create(owner_id:1, assignee_id: 2)
This allows me to perform Task.first.owner which returns user one and Task.first.assignee which returns user two but User.first.task returns nothing. Which is because task doesn't belong to a user, they belong to owner and assignee. So,
Attempt 2:
class User < ActiveRecord::Base
has_many :tasks, foreign_key: [:owner_id, :assignee_id]
end
class Task < ActiveRecord::Base
belongs_to :user
end
That just fails altogether as two foreign keys don't seem to be supported.
So what I want is to be able to say User.tasks and get both the users owned and assigned tasks.
Basically somehow build a relationship that would equal a query of Task.where(owner_id || assignee_id == 1)
Is that possible?
Update
I'm not looking to use finder_sql, but this issue's unaccepted answer looks to be close to what I want: Rails - Multiple Index Key Association
So this method would look like this,
Attempt 3:
class Task < ActiveRecord::Base
def self.by_person(person)
where("assignee_id => :person_id OR owner_id => :person_id", :person_id => person.id
end
end
class Person < ActiveRecord::Base
def tasks
Task.by_person(self)
end
end
Though I can get it to work in Rails 4, I keep getting the following error:
ActiveRecord::PreparedStatementInvalid: missing value for :owner_id in :donor_id => :person_id OR assignee_id => :person_id
TL;DR
class User < ActiveRecord::Base
def tasks
Task.where("owner_id = ? OR assigneed_id = ?", self.id, self.id)
end
end
Remove has_many :tasks in User class.
Using has_many :tasks doesn't make sense at all as we do not have any column named user_id in table tasks.
What I did to solve the issue in my case is:
class User < ActiveRecord::Base
has_many :owned_tasks, class_name: "Task", foreign_key: "owner_id"
has_many :assigned_tasks, class_name: "Task", foreign_key: "assignee_id"
end
class Task < ActiveRecord::Base
belongs_to :owner, class_name: "User"
belongs_to :assignee, class_name: "User"
# Mentioning `foreign_keys` is not necessary in this class, since
# we've already mentioned `belongs_to :owner`, and Rails will anticipate
# foreign_keys automatically. Thanks to #jeffdill2 for mentioning this thing
# in the comment.
end
This way, you can call User.first.assigned_tasks as well as User.first.owned_tasks.
Now, you can define a method called tasks that returns the combination of assigned_tasks and owned_tasks.
That could be a good solution as far the readability goes, but from performance point of view, it wouldn't be that much good as now, in order to get the tasks, two queries will be issued instead of once, and then, the result of those two queries need to be joined as well.
So in order to get the tasks that belong to a user, we would define a custom tasks method in User class in the following way:
def tasks
Task.where("owner_id = ? OR assigneed_id = ?", self.id, self.id)
end
This way, it will fetch all the results in one single query, and we wouldn't have to merge or combine any results.
Extending upon #dre-hh's answer above, which I found no longer works as expected in Rails 5. It appears Rails 5 now includes a default where clause to the effect of WHERE tasks.user_id = ?, which fails as there is no user_id column in this scenario.
I've found it is still possible to get it working with a has_many association, you just need to unscope this additional where clause added by Rails.
class User < ApplicationRecord
has_many :tasks, ->(user) {
unscope(:where).where(owner: user).or(where(assignee: user)
}
end
Rails 5:
you need to unscope the default where clause
see #Dwight answer if you still want a has_many associaiton.
Though User.joins(:tasks) gives me
ArgumentError: The association scope 'tasks' is instance dependent (the scope block takes an argument). Preloading instance dependent scopes is not supported.
As it is no longer possible you can use #Arslan Ali solution as well.
Rails 4:
class User < ActiveRecord::Base
has_many :tasks, ->(user){ where("tasks.owner_id = :user_id OR tasks.assignee_id = :user_id", user_id: user.id) }
end
Update1:
Regarding #JonathanSimmons comment
Having to pass the user object into the scope on the User model seems like a backwards approach
You don't have to pass the user model to this scope.
The current user instance is passed automatically to this lambda.
Call it like this:
user = User.find(9001)
user.tasks
Update2:
if possible could you expand this answer to explain what's happening? I'd like to understand it better so I can implement something similar. thanks
Calling has_many :tasks on ActiveRecord class will store a lambda function in some class variable and is just a fancy way to generate a tasks method on its object, which will call this lambda. The generated method would look similar to following pseudocode:
class User
def tasks
#define join query
query = self.class.joins('tasks ON ...')
#execute tasks_lambda on the query instance and pass self to the lambda
query.instance_exec(self, self.class.tasks_lambda)
end
end
I worked out a solution for this. I'm open to any pointers on how I can make this better.
class User < ActiveRecord::Base
def tasks
Task.by_person(self.id)
end
end
class Task < ActiveRecord::Base
scope :completed, -> { where(completed: true) }
belongs_to :owner, class_name: "User", foreign_key: "owner_id"
belongs_to :assignee, class_name: "User", foreign_key: "assignee_id"
def self.by_person(user_id)
where("owner_id = :person_id OR assignee_id = :person_id", person_id: user_id)
end
end
This basically overrides the has_many association but still returns the ActiveRecord::Relation object I was looking for.
So now I can do something like this:
User.first.tasks.completed and the result is all completed task owned or assigned to the first user.
Since Rails 5 you can also do that which is the ActiveRecord safer way:
def tasks
Task.where(owner: self).or(Task.where(assignee: self))
end
My answer to Associations and (multiple) foreign keys in rails (3.2) : how to describe them in the model, and write up migrations is just for you!
As for your code,here are my modifications
class User < ActiveRecord::Base
has_many :tasks, ->(user) { unscope(where: :user_id).where("owner_id = ? OR assignee_id = ?", user.id, user.id) }, class_name: 'Task'
end
class Task < ActiveRecord::Base
belongs_to :owner, class_name: "User", foreign_key: "owner_id"
belongs_to :assignee, class_name: "User", foreign_key: "assignee_id"
end
Warning:
If you are using RailsAdmin and need to create new record or edit existing record,please don't do what I've suggested.Because this hack will cause problem when you do something like this:
current_user.tasks.build(params)
The reason is that rails will try to use current_user.id to fill task.user_id,only to find that there is nothing like user_id.
So,consider my hack method as an way outside the box,but don't do that.
Better way is using polymorphic association:
task.rb
class Task < ActiveRecord::Base
belongs_to :taskable, polymorphic: true
end
assigned_task.rb
class AssignedTask < Task
end
owned_task.rb
class OwnedTask < Task
end
user.rb
class User < ActiveRecord::Base
has_many :assigned_tasks, as: :taskable, dependent: :destroy
has_many :owned_tasks, as: :taskable, dependent: :destroy
end
In result, we can use it so:
new_user = User.create(...)
AssignedTask.create(taskable: new_user, ...)
OwnedTask.create(taskable: new_user, ...)
pp user.assigned_tasks
pp user.owned_tasks
A Contact has a User assigned to them:
class Contact < ActiveRecord::Base
...
belongs_to :user
...
end
The user model has a field I want to exclude any time a user object or objects are returned from db. One of the ways to make it work is to add a default scope:
class User < ActiveRecord::Base
...
has_many :contacts
...
default_scope select((column_names - ['encrypted_password']).map { |column_name| "`#{table_name}`.`#{column_name}`"})
end
So in console if I do:
User.first
The select statement and result set do not include 'encrypted_password'.
However, if I do:
c = Contact.includes(:user).first
c.user
they do. The default scope on the User model does not get applied in this case and the 'encrypted_password' field is shown.
So my question is why? And also, is there a clean way to specify what fields should be returned on related object(s)?
You should just be able to use the :select option on the belongs_to relationship. Something like this:
class Contact < ActiveRecord::Base
...
belongs_to :user, :select => [:id, :first_name, :last_name, :email]
...
end