CODEWITHSUNDEEP
ruby-on-railsrubyactivemodel
mabu
mabu

Reputation: 307

How to access instance variable from a Rails model?

I've defined an instance variable in my ApplicationController like that:

@team = Team.find(params[:team_id])

Now, in my EventsCreator model I'd like to access @team from above:

class EventsCreator
  # ...

  def team_name
    name = @team.name
    # ...
  end

  # ...
end

With that code I get the following error:

undefined method `name' for nil:NilClass

How should I access instance variables like this from a model? Is there a better way or better practice to do so?

Edit 1:

The event.rb model is the model which contains common information which is also saved in the database:

class Event < ApplicationRecord
  belongs_to :team
  attr_accessor :comment
  ...
end

The events_creator.rb model is kind of an extension to event.rb. It contains some logic e.g. for repeating events:

class EventsCreator
  include ActiveModel::Model
  attr_accessor :beginning, :ending, :repeat_frequency, :repeat_until_date
  ...
end

EventsCreator does not directly create Records in the DB. It just does some logic and saves the data through Event model.

Now without having a direct relation to team.rb I want to be able to access the instance variable @team which is defined in application_controller.rb:

class ApplicationController < ApplicationController::Base
  before_action :set_team_for_nested

  private
  def set_team_for_nested
    @team = Team.find(params[:team_id])
  end
end

My routes.rb file is nesting all routes inside team because I need the team_id for every action:

Rails.application.routes.draw do
  resources :teams do
    resources :events
    get '/events_creator', to: 'events_creator#new', as: 'new_events_creator'
    post '/events_creator', to: 'events_creator#create', as: 'create_events_creator'
  end
end

Now I have no idea how to access the @team instance variable (which I thought is defined for the whole application) from a model. Since I'm quite new to Rails, I might have messed up things, please tell me if there are better ways to achieve the same.

Upvotes: 4

Views: 3158

Answers (2)

patkoperwas
patkoperwas

Reputation: 1369

You will have to pass the team as an argument to your class.

class EventsCreator
  attr_reader :team
  def initialize(team)
    @team = team
  end

  def some_method
    puts team.name
  end
end

# Then in your controller you can do this
def create
  EventsCreator.new(@team)
end

If you plan on including ActiveModel::Model then you can just do

class EventsCreator
  include ActiveModel::Model
  attr_accessor :team

  def some_method
    puts team.name
  end
end

# And then in your controller it's the same thing
def create
  EventsCreator.new(@team)
end

Upvotes: 1

marmeladze
marmeladze

Reputation: 6564

simple

class EventCreator

  ...

  def team_name
    name #will return name of class instance
    #or do something with it
  end
end

Upvotes: -1

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