Validate project and environment instead of only requiring

app/models/deployment.rb

 class Deployment < ActiveRecord::Base
   include InternalId
 
-  belongs_to :project, required: true
-  belongs_to :environment, required: true
+  belongs_to :project, validate: true
+  belongs_to :environment, validate: true
   belongs_to :user
   belongs_to :deployable, polymorphic: true
 

db/migrate/20160610204157_add_deployments.rb

@@ -7,8 +7,8 @@ class AddDeployments < ActiveRecord::Migration
   def change
     create_table :deployments, force: true do |t|
       t.integer  :iid,            null: false
-      t.integer  :project_id
-      t.integer  :environment_id
+      t.integer  :project_id,     null: false
+      t.integer  :environment_id, null: false
       t.string   :ref,            null: false
       t.boolean  :tag,            null: false
       t.string   :sha,            null: false