app/models/wedding.rb

@@ -15,6 +15,8 @@
 #  index_weddings_on_slug  (slug) UNIQUE
 #
 class Wedding < ApplicationRecord
+  SLUG_REGEX = /[a-z\d-]+/
+
   validates :date, presence: true
-  validates :slug, presence: true, uniqueness: true, format: { with: /\A[a-z]+\z/ }
+  validates :slug, presence: true, uniqueness: true, format: { with: /\A#{SLUG_REGEX}\z/ }
 end

config/routes.rb

@@ -2,7 +2,7 @@
 
 Rails.application.routes.draw do
   mount LetterOpenerWeb::Engine, at: "/letter_opener" if Rails.env.development?
-  scope ":slug", constraints: { slug: /[a-z]+/ } do
+  scope ":slug", constraints: { slug: Wedding::SLUG_REGEX } do
     devise_for :users, skip: [:registration, :session, :confirmation]
     devise_scope :user do
       post 'users', to: 'users/registrations#create'

spec/models/wedding_spec.rb

@@ -3,5 +3,20 @@
 require 'rails_helper'
 
 RSpec.describe Wedding, type: :model do
-  pending "add some examples to (or delete) #{__FILE__}"
+  describe 'validations' do
+    subject { build(:wedding) }
+    describe 'slug' do
+      it { should allow_value('foo').for(:slug) }
+      it { should allow_value('foo-bar').for(:slug) }
+      it { should allow_value('foo-123').for(:slug) }
+      it { should allow_value('foo-123-').for(:slug) }
+      it { should allow_value('foo--123').for(:slug) }
+
+      it { should_not allow_value('Foo').for(:slug) }
+      it { should_not allow_value('/foo').for(:slug) }
+      it { should_not allow_value('foo/123').for(:slug) }
+      it { should_not allow_value('foo_123').for(:slug) }
+      it { should_not allow_value('foo/').for(:slug) }
+    end
+  end
 end

spec/requests/schemas.rb

@@ -14,6 +14,7 @@ module Swagger
       name: 'slug',
       in: :path,
       type: :string, 
+      pattern: Wedding::SLUG_REGEX,
       example: :default,
       description: 'Wedding slug'
     }