Ruby on Rails App Works Locally But Does Not Work On Heroku

Solution 1

Error Indication

The description of the problems says that there is no method defined as find_by_remember_token for the User Class.

When a developer tries to run a method that is not defined on the object in Ruby, it typically raises a NoMethodError. This error occurs when you attempt to invoke a method on an object that doesn’t have that method defined.

Please see the logs shared from the issue.

2012-07-18T06:10:26+00:00 app[web.1]: ActionView::Template::Error (undefined method `find_by_remember_token' for #<Class:0x00000004960740>):

Error Diagnosis

As per my thinking the questioner, Created added a new column remember_token to its user model. To add a new column to an attribute in Rails users need to create a new migration file. You can see the syntax of adding a new column to an model

class NameOfYourMigration < ActiveRecord::Migration
  def change
    add_column :users, :remember_token, :string
  end
end

After creating a migration user needs to run the following command to reflect migration changes into the database changes.

rake db:migrate

Once you successfully run the migration the new attribute is added to the table.

Users can verify newly created columns added to respective tables by checking the schema.rb OR Users can open the rails console and check the model attributes.
The find_by_remember_token is a type of Dynamic finder method. These methods are automatically created based on the database columns of a model.

To deploy the same changes on the Heroku user needs to follow the same steps.

Push the changes to Heroku application using the following command.

git push heroku master

After pushing the changes, the user needs to run the migrate command on the heroku as well. The command to run migration on the heroku listed below:-

heroku run rake db:migrate

Error Cause

If a user experiences an undefined method 'find_by_remember_token' error on Heroku after running a migration locally, it's possible that the migration hasn't been applied on the Heroku database

Error Resolutions

After running the migration locally, make sure to apply the migration on your Heroku app. Use the following command:

heroku run rake db:migrate

After applying the migration, restart your Heroku app to ensure that any changes take effect:

heroku restart –app application_name

You can also try running the problematic method in the Heroku Rails console to see if the issue persists:

heroku run rails console

And then in the console:

User.find_by_remember_token(token)

Solution 2

Error Indication

The description of the problems says that there is no method defined as find_by_remember_token for the User Class.
When a developer tries to run a method that is not defined on the object in Ruby, it typically raises a NoMethodError. This error occurs when you attempt to invoke a method on an object that doesn't have that method defined.

Error Resolutions

Further checking the Hartl Tutorial I have identified the missing piece of information. We need to add the remember_token to the attr_accessible. You can add the attr_accessible using the following way.

class User < ActiveRecord
  attr_accessible :name, :email, :password, :password_confirmation, :remember_token
end

Adding :remember_token to the list of accessible attributes using attr_accessible is a common step in Ruby on Rails 3 applications, especially when dealing with user authentication and sessions.

To further clarify, the attr_accessible method is a part of the protected_attributes gem in Rails. It allows you to specify which attributes can be mass-assigned using methods like update_attributes or during the creation of a new record.

The addition of :remember_token to the accessible attributes ensures that the remember_token attribute can be properly assigned when needed, which is crucial for functionality related to user sessions, authentication, and remember me functionality.

After adding :remember_token to the list existing att_accesssible . User needs to push the changes to the heroku using the following command.