Auth: associate Links to Users

app/graphql/mutations/create_link.rb

@@ -11,6 +11,7 @@ def resolve(description: nil, url: nil)
       Link.create!(
         description: description,
         url: url,
+        user: context[:current_user]
       )
     end
   end

app/graphql/types/link_type.rb

@@ -3,5 +3,9 @@ class LinkType < Types::BaseObject
     field :id, ID, null: false
     field :url, String, null: false
     field :description, String, null: false
+    # `posted_by` is automatically camelcased as `postedBy`
+    # 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
   end
 end

app/models/link.rb

@@ -1,2 +1,3 @@
 class Link < ApplicationRecord
+  belongs_to :user
 end

db/migrate/20201201040432_add_user_id_link.rb

@@ -0,0 +1,7 @@
+class AddUserIdLink < ActiveRecord::Migration[6.0]
+  def change
+    change_table :links do |t|
+      t.references :user, foreign_key: true
+    end
+  end
+end

db/schema.rb

@@ -10,13 +10,15 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2020_11_30_014852) do
+ActiveRecord::Schema.define(version: 2020_12_01_040432) do
 
   create_table "links", force: :cascade do |t|
     t.string "url"
     t.text "description"
     t.datetime "created_at", precision: 6, null: false
     t.datetime "updated_at", precision: 6, null: false
+    t.integer "user_id"
+    t.index ["user_id"], name: "index_links_on_user_id"
   end
 
   create_table "users", force: :cascade do |t|
@@ -27,4 +29,5 @@
     t.datetime "updated_at", precision: 6, null: false
   end
 
+  add_foreign_key "links", "users"
 end