Votes model + Users can vote on Links

app/graphql/mutations/create_vote.rb

@@ -0,0 +1,14 @@
+module Mutations
+  class CreateVote < BaseMutation
+    argument :link_id, ID, required: false
+
+    type Types::VoteType
+
+    def resolve(link_id: nil)
+      Vote.create!(
+        link: Link.find(link_id),
+        user: context[:current_user]
+      )
+    end
+  end
+end

app/graphql/types/date_time_type.rb

@@ -0,0 +1,13 @@
+# Add DateTimeType for Link.created_at property
+# https://github.com/rmosolgo/graphiql-rails/issues/29
+module Types
+  class DateTimeType < BaseScalar
+    def self.coerce_input(value, _context)
+      Time.zone.parse(value)
+    end
+
+    def self.coerce_result(value, _context)
+      value.utc.iso8601
+    end
+  end
+end

app/graphql/types/link_type.rb

@@ -7,5 +7,6 @@ class LinkType < Types::BaseObject
     # field can be nil, because we added users relationship later
     # "method" option remaps field to an attribute of Link model
     field :posted_by, UserType, null: true, method: :user
+    field :votes, [Types::VoteType], null: false
   end
 end

app/graphql/types/mutation_type.rb

@@ -3,5 +3,6 @@ class MutationType < BaseObject
     field :create_link, mutation: Mutations::CreateLink
     field :create_user, mutation: Mutations::CreateUser
     field :login_user, mutation: Mutations::LoginUser
+    field :create_vote, mutation: Mutations::CreateVote
   end
 end

app/graphql/types/user_type.rb

@@ -1,7 +1,10 @@
 module Types
   class UserType < Types::BaseObject
     field :id, ID, null: false
+    field :created_at, DateTimeType, null: false
     field :name, String, null: false
     field :email, String, null: false
+    field :votes, [VoteType], null: false
+    field :links, [LinkType], null: false
   end
 end

app/graphql/types/vote_type.rb

@@ -0,0 +1,7 @@
+module Types
+  class VoteType < Types::BaseObject
+    field :id, ID, null: false
+    field :user, Types::UserType, null: false
+    field :link, Types::LinkType, null: false
+  end
+end

app/models/link.rb

@@ -1,3 +1,5 @@
 class Link < ApplicationRecord
-  belongs_to :user
+  belongs_to :user, optional: true # Prevent ActiveRecord::RecordInvalid
+
+  has_many :votes
 end

app/models/user.rb

@@ -3,4 +3,7 @@ class User < ApplicationRecord
 
   validates :name, presence: true
   validates :email, presence: true, uniqueness: true
+
+  has_many :votes
+  has_many :links
 end

app/models/vote.rb

@@ -0,0 +1,4 @@
+class Vote < ApplicationRecord
+  belongs_to :link
+  belongs_to :user
+end

db/migrate/20201201042112_create_votes.rb

@@ -0,0 +1,10 @@
+class CreateVotes < ActiveRecord::Migration[6.0]
+  def change
+    create_table :votes do |t|
+      t.references :link, null: false, foreign_key: true
+      t.references :user, null: false, foreign_key: true
+
+      t.timestamps
+    end
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2020_12_01_040432) do
+ActiveRecord::Schema.define(version: 2020_12_01_042112) do
 
   create_table "links", force: :cascade do |t|
     t.string "url"
@@ -29,5 +29,16 @@
     t.datetime "updated_at", precision: 6, null: false
   end
 
+  create_table "votes", force: :cascade do |t|
+    t.integer "link_id", null: false
+    t.integer "user_id", null: false
+    t.datetime "created_at", precision: 6, null: false
+    t.datetime "updated_at", precision: 6, null: false
+    t.index ["link_id"], name: "index_votes_on_link_id"
+    t.index ["user_id"], name: "index_votes_on_user_id"
+  end
+
   add_foreign_key "links", "users"
+  add_foreign_key "votes", "links"
+  add_foreign_key "votes", "users"
 end

test/fixtures/votes.yml

@@ -0,0 +1,9 @@
+# Read about fixtures at https://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
+
+one:
+  link: one
+  user: one
+
+two:
+  link: two
+  user: two

test/models/vote_test.rb

@@ -0,0 +1,7 @@
+require 'test_helper'
+
+class VoteTest < ActiveSupport::TestCase
+  # test "the truth" do
+  #   assert true
+  # end
+end