Rails 5.1 add a specific column as foreign key - ruby-on-rails

Question

I have a issue with foreign keys.
I have 3 tables : Users, Members and Groups.
Basically I want the user to be able to create groups. The user provide a name, a description and on create a token is generated. Then other users can join this group via the members table. The members table has user_id and group_id. User can join the group providing the group_id which is not very cool, instead I would like the users to join the group providing the token.
Everything is working except the fact that they can join with the token. My question is how can I use the token instead of the group_id ?
I already tried to add foreign keys like this but nothing is going on in the schema :
add_foreign_key :members, :groups, column: :group_id, primary_key: :auth_token
add_foreign_key :members, :groups, column: :auth_token, primary_key: :auth_token
I also tried to add foreign key in my model :
belongs_to :group, foreign_key: "group_auth_token"
has_many :members, foreign_key: "group_auth_token", class_name: "Group"
Here are my actual models in case :
Group.rb
class Group < ApplicationRecord
has_secure_token :auth_token
has_many :members, :dependent => :destroy
has_many :users, :through => :members
end
User.rb
class User < ApplicationRecord
has_secure_password
has_many :members, :dependent => :destroy
has_many :groups, :through => :members
end
Member.rb
class Member < ApplicationRecord
belongs_to :user
belongs_to :group
validates :user_id, :presence => true
validates :group_id, :presence => true
validates :user_id, :uniqueness => {:scope => [:user_id, :group_id]}
end
I'm really confused with all this, I'm pretty sure the answer is obvious but I'm just lost, anybody to help me out ?
Thanks
EDIT : It looks like it's not clear enough so I'm adding a few things. When the user create the group this is what's happening in my controller :
def create
#group = Group.new group_params
#group.owner_id = current_user.id if current_user
if #group.save
#user = current_user.id if current_user
Member.create(group_id: "#{#group.id}", user_id: "#{#user}")
flash[:success] = "The Group has been created."
redirect_to group_path(#group)
else
render 'new'
end
end
The Member.create is to add the User automatically in the group. If anybody want's to join a group this is what is going on in my member controller :
def create
#member = Member.new member_params
#member.user_id = current_user.id if current_user
if #member.save
flash[:success] = "You Joined the Group."
redirect_to mygroups_path
else
flash.now[:error] = "Something went wrong. Are you in the group already ?"
render 'new'
end
end
And of course there is a form to create a new member (join the group) where the user provide the group_id (member_params) in the controller.
I want to be able to use the token instead of the group_id.
EDIT 2 :
So I have a error with your code jvillian. I paste it in the MembersController. In my form I changed the :group_id by :auth_token and this is my form :
<%= form_for #member do |f| %>
<%= f.label :auth_token %>
<%= f.text_field :auth_token %>
<%= f.submit "Join the Group" %>
<% end %>

Answer 1

This code may not be exactly correct, but it should be in the right direction.
def create
if #group = Group.find_by(auth_token: params[:auth_token]) && current_user
if #group.users << current_user
flash[:success] = "You Joined the Group."
redirect_to mygroups_path
else
flash.now[:error] = "Something went wrong. Are you in the group already ?"
render 'new'
end
end
end
I put in:
params[:token]
Naturally, that may not be quite right. Adjust to fit your own params.
This bit:
if #group.users << current_user
may not be correct as I forget what the shovel operator returns. But, you can look that up in the guide.
TO CORRECT YOUR FORM
Presumably, you're doing something like:
class MembersController < ApplicationController
def new
#member = Member.new
end
...
end
So, when you do this:
<%= form_for #member do |f| %>
<%= f.label :auth_token %>
<%= f.text_field :auth_token %>
<%= f.submit "Join the Group" %>
<% end %>
form_for can access your #member instance.
BUT, when you do this:
<%= f.text_field :auth_token %>
You're getting an error because form_for is trying to access the .auth_token attribute on #member which, naturally, doesn't exist. But remember, all you're trying to do here is submit a form that has a token. So, instead, do something like:
<%= form_for #member do |f| %>
<%= label_tag 'auth_token', 'Token' %>
<%= text_field_tag 'auth_token' %>
<%= f.submit "Join the Group" %>
<% end %>
In this way, the auth_token field is no longer directly derived from #member and you're no longer trying to access a non-existent method on #member.
Your params will look something like:
Parameters: {"auth_token"=>"whatever the user entered"}
If you want the auth_token to be nested inside group, like this:
Parameters: {"group"=>{"auth_token"=>"whatever the user entered"}}
Then do:
<%= form_for #member do |f| %>
<%= label_tag 'group[auth_token]', 'Token' %>
<%= text_field_tag 'group[auth_token]' %>
<%= f.submit "Join the Group" %>
<% end %>

Answer 2

Your text is abit confusing, but maybe this setup of the references are what you are looking for?
add_reference :members, :group_auth_token, foreign_key: { to_table: :groups }, references: :auth_token