[STORE] Warn that the ActiveRecord persistence pattern is deprecated (#809)

Author: estolfo

elasticsearch-persistence/README.md

@@ -445,6 +445,9 @@ and demonstrates a rich set of features:
 
 ### The ActiveRecord Pattern
 
+Please note that this pattern is deprecated and will be removed in version 6.0.
+The [Repository Pattern](#the-repository-pattern) is recommended instead.
+
 The `Elasticsearch::Persistence::Model` module provides an implementation of the
 active record [pattern](http://www.martinfowler.com/eaaCatalog/activeRecord.html),
 with a familiar interface for using Elasticsearch as a persistence layer in

elasticsearch-persistence/lib/elasticsearch/persistence/model.rb

@@ -66,6 +66,22 @@ def gateway(&block)
               @gateway
             end
 
+            DEPRECATION_WARNING = "This (ActiveRecord) persistence pattern is deprecated. It will be removed in " +
+              "version 6.0 in favor of the Repository pattern. Please see the ReadMe for " +
+              "details on the alternative pattern.\n" +
+              "https://github.com/elastic/elasticsearch-rails/tree/master/elasticsearch-persistence" +
+              "#the-repository-pattern".freeze
+
+            # Warn that this ActiveRecord persistence pattern is deprecated.
+            #
+            def raise_deprecation_warning!
+              if STDERR.tty?
+                Kernel.warn("\e[31;1m#{DEPRECATION_WARNING}\e[0m")
+              else
+                Kernel.warn(DEPRECATION_WARNING)
+              end
+            end
+
             # Delegate methods to repository
             #
             delegate :settings,
@@ -126,6 +142,8 @@ def deserialize(document)
           attribute :updated_at, Time, default: lambda { |o,a| Time.now.utc }
 
           attr_reader :hit
+
+          raise_deprecation_warning!
         end
 
       end

elasticsearch-persistence/test/integration/model/model_basic_test.rb

@@ -33,6 +33,11 @@ class ::Person
           Person.create_index! force: true
         end
 
+        should "warn that the ActiveRecord persistence pattern is deprecated" do
+          Kernel.expects(:warn).at_least_once
+          class ShouldWarn; include Elasticsearch::Persistence::Model; end
+        end
+
         should "save the object with custom ID" do
           person = Person.new id: 1, name: 'Number One'
           person.save