init project

app/models/member.rb

@@ -0,0 +1,11 @@
+class Member < ApplicationRecord
+  belongs_to :user
+  belongs_to :course, optional: true
+  belongs_to :project, optional: true
+
+  has_many :member_roles, dependent: :destroy
+  has_many :roles, through: :member_roles
+
+  validates :user_id, :project_id, presence: true
+
+end