Rails: Unpermitted parameter in Rails 5

It's not the inflection of the word "criteria" that's giving you problems (although you can add a custom inflector to get the singular and plural versions you prefer if you really want).

The issue is that you have to explicitly permit the fields of nested objects.

Change your current params:

params.require(:project).permit(:name,  project_criteria: [] )

To this (for a single nested object):

params.require(:project).permit(:name,  project_criteria: [:name, :type, :benefit] )

Your case is somewhat compounded by the fact that you're dealing with multiple nested objects, so you'll have to pass a hash instead:

params.require(:project).permit(:name,  { project_criteria: [:name, :type, :benefit]} )

I had this issue when working on a Rails 6 application.

My application consists of a User model that has a one-to-one relationship a Personal_Info model

My original code was this:

User Model

class User < ApplicationRecord   has_one :personal_info, class_name: 'PersonalInfo', dependent: :destroy  accepts_nested_attributes_for :personal_info, allow_destroy: trueend

Personal Info Model

class PersonalInfo < ApplicationRecord  belongs_to :userend

User Controller

class UsersController < ApplicationController  def index    @users = User.all  end  .  .  def user_params    params.require(:user).permit(:email, :password, :password_confirmation,                                 personal_info_attributes: [:first_name,                                   :last_name, :phone, :gender, :dob,                                  :address, :city, :state, :country])  endend

The issue was that I did not add the Personal_Info id to the accepted user params (parameters).

Here's how I fixed it:

I simply had to add the Personal_Info id to the UsersController params this way:

User Controller

class UsersController < ApplicationController  def index    @users = User.all  end  .  .  def user_params    params.require(:user).permit(:email, :password, :password_confirmation,                                 personal_info_attributes: [:id, :first_name,                                   :last_name, :phone, :gender, :dob,                                  :address, :city, :state, :country])  endend

Another way is to add the update_only option to the Users Model this way:

class User < ApplicationRecord   has_one :personal_info, class_name: 'PersonalInfo', dependent: :destroy  accepts_nested_attributes_for :personal_info, update_only: true, allow_destroy: trueend

That's all.

I hope this helps