From b7b3e20333056fcec4725b3f87659acbcd214ee4 Mon Sep 17 00:00:00 2001
From: fatkodima <fatkodima123@gmail.com>
Date: Thu, 25 Jan 2018 22:11:11 +0200
Subject: [PATCH] Dump correctly index nulls order for postgresql

---
 .../postgresql/schema_statements.rb           |  8 ++++--
 .../adapters/postgresql/active_schema_test.rb |  6 ++++
 .../cases/adapters/postgresql/schema_test.rb  | 28 +++++++++++++++++++
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
index 8678fab2ac..7999434ad8 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -124,9 +124,13 @@ module ActiveRecord
 
               # add info on sort order (only desc order is explicitly specified, asc is the default)
               # and non-default opclasses
-              expressions.scan(/(\w+)(?: (?!DESC)(\w+))?(?: (DESC))?/).each do |column, opclass, desc|
+              expressions.scan(/(?<column>\w+)\s?(?<opclass>\w+_ops)?\s?(?<desc>DESC)?\s?(?<nulls>NULLS (?:FIRST|LAST))?/).each do |column, opclass, desc, nulls|
                 opclasses[column] = opclass.to_sym if opclass
-                orders[column] = :desc if desc
+                if nulls
+                  orders[column] = [desc, nulls].compact.join(" ")
+                else
+                  orders[column] = :desc if desc
+                end
               end
             end
 
diff --git a/activerecord/test/cases/adapters/postgresql/active_schema_test.rb b/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
index 99c53dadeb..308ad1d854 100644
--- a/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
@@ -62,6 +62,12 @@ class PostgresqlActiveSchemaTest < ActiveRecord::PostgreSQLTestCase
     expected = %(CREATE  INDEX  "index_people_on_last_name" ON "people" USING gist ("last_name" bpchar_pattern_ops))
     assert_equal expected, add_index(:people, :last_name, using: :gist, opclass: { last_name: :bpchar_pattern_ops })
 
+    expected = %(CREATE  INDEX  "index_people_on_last_name_and_first_name" ON "people"  ("last_name" DESC NULLS LAST, "first_name" ASC))
+    assert_equal expected, add_index(:people, [:last_name, :first_name], order: { last_name: "DESC NULLS LAST", first_name: :asc })
+
+    expected = %(CREATE  INDEX  "index_people_on_last_name" ON "people"  ("last_name" NULLS FIRST))
+    assert_equal expected, add_index(:people, :last_name, order: "NULLS FIRST")
+
     assert_raise ArgumentError do
       add_index(:people, :last_name, algorithm: :copy)
     end
diff --git a/activerecord/test/cases/adapters/postgresql/schema_test.rb b/activerecord/test/cases/adapters/postgresql/schema_test.rb
index 2c99fa78bd..7ad03c194f 100644
--- a/activerecord/test/cases/adapters/postgresql/schema_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/schema_test.rb
@@ -532,6 +532,34 @@ class SchemaIndexOpclassTest < ActiveRecord::PostgreSQLTestCase
   end
 end
 
+class SchemaIndexNullsOrderTest < ActiveRecord::PostgreSQLTestCase
+  include SchemaDumpingHelper
+
+  setup do
+    @connection = ActiveRecord::Base.connection
+    @connection.create_table "trains" do |t|
+      t.string :name
+      t.text :description
+    end
+  end
+
+  teardown do
+    @connection.drop_table "trains", if_exists: true
+  end
+
+  def test_nulls_order_is_dumped
+    @connection.execute "CREATE INDEX trains_name_and_description ON trains USING btree(name NULLS FIRST, description)"
+    output = dump_table_schema "trains"
+    assert_match(/order: \{ name: "NULLS FIRST" \}/, output)
+  end
+
+  def test_non_default_order_with_nulls_is_dumped
+    @connection.execute "CREATE INDEX trains_name_and_desc ON trains USING btree(name DESC NULLS LAST, description)"
+    output = dump_table_schema "trains"
+    assert_match(/order: \{ name: "DESC NULLS LAST" \}/, output)
+  end
+end
+
 class DefaultsUsingMultipleSchemasAndDomainTest < ActiveRecord::PostgreSQLTestCase
   setup do
     @connection = ActiveRecord::Base.connection