- working party

- working friend
- working attendent

app/models/attendent.rb

@@ -1,4 +1,4 @@
 class Attendent < ApplicationRecord
-  belongs_to :parties
-  belongs_to :friends
+  belongs_to :party
+  belongs_to :friend
 end

app/models/friend.rb

@@ -1,4 +1,7 @@
 class Friend < ApplicationRecord
+  has_many :attendents
+  has_many :parties, through: :attendents
+
   validates :firstname, :lastname, :email, :telefon, presence: true
 
   def fullname

app/models/party.rb

@@ -1,3 +1,6 @@
 class Party < ApplicationRecord
+  has_many :attendents
+  has_many :friends, through: :attendents
+
   validates :title, :location, :start_date, :start_time, :status, presence: true
 end