Escape underscore wildcard for pg and mysql.

lib/ransack/adapters/active_record/ransack/constants.rb

@@ -104,7 +104,7 @@ def escape_wildcards(unescaped)
       case ActiveRecord::Base.connection.adapter_name
       when "Mysql2".freeze, "PostgreSQL".freeze
         # Necessary for PostgreSQL and MySQL
-        unescaped.to_s.gsub(/([\\|\%|.])/, '\\\\\\1')
+        unescaped.to_s.gsub(/([\\|\%|_|.])/, '\\\\\\1')
       else
         unescaped
       end

spec/ransack/adapters/active_record/base_spec.rb

@@ -190,6 +190,30 @@ def self.sane_adapter?
             expect(s.result.to_a).to eq [p]
           end
 
+          context 'searching by underscores' do
+            # when escaping is supported right in LIKE expression without adding extra expressions
+            def self.simple_escaping?
+              case ::ActiveRecord::Base.connection.adapter_name
+                when "Mysql2", "PostgreSQL"
+                  true
+                else
+                  false
+              end
+            end
+
+            it "should search correctly if matches exist" do
+              p = Person.create!(:name => "name_with_underscore")
+              s = Person.ransack(:name_cont => "name_")
+              expect(s.result.to_a).to eq [p]
+            end if simple_escaping?
+
+            it "should return empty result if no matches" do
+              Person.create!(:name => "name_with_underscore")
+              s = Person.ransack(:name_cont => "n_")
+              expect(s.result.to_a).to eq []
+            end if simple_escaping?
+          end
+
           context "searching on an `in` predicate with a ransacker" do
             it "should function correctly when passing an array of ids" do
               s = Person.ransack(array_users_in: true)

spec/ransack/predicate_spec.rb

@@ -16,7 +16,7 @@ module Ransack
         expect { subject.result }.to_not raise_error
       end
 
-      it "escapes '%', '.' and '\\\\' in value" do
+      it "escapes '%', '.', '_' and '\\\\' in value" do
         subject.send(:"#{method}=", '%._\\')
         expect(subject.result.to_sql).to match(regexp)
       end
@@ -124,9 +124,9 @@ module Ransack
     describe 'cont' do
       it_has_behavior 'wildcard escaping', :name_cont,
         (if ActiveRecord::Base.connection.adapter_name == "PostgreSQL"
-          /"people"."name" ILIKE '%\\%\\._\\\\%'/
+          /"people"."name" ILIKE '%\\%\\.\\_\\\\%'/
         elsif ActiveRecord::Base.connection.adapter_name == "Mysql2"
-          /`people`.`name` LIKE '%\\\\%\\\\._\\\\\\\\%'/
+          /`people`.`name` LIKE '%\\\\%\\\\.\\\\_\\\\\\\\%'/
         else
          /"people"."name" LIKE '%%._\\%'/
         end) do
@@ -143,9 +143,9 @@ module Ransack
     describe 'not_cont' do
       it_has_behavior 'wildcard escaping', :name_not_cont,
         (if ActiveRecord::Base.connection.adapter_name == "PostgreSQL"
-          /"people"."name" NOT ILIKE '%\\%\\._\\\\%'/
+          /"people"."name" NOT ILIKE '%\\%\\.\\_\\\\%'/
         elsif ActiveRecord::Base.connection.adapter_name == "Mysql2"
-          /`people`.`name` NOT LIKE '%\\\\%\\\\._\\\\\\\\%'/
+          /`people`.`name` NOT LIKE '%\\\\%\\\\.\\\\_\\\\\\\\%'/
         else
          /"people"."name" NOT LIKE '%%._\\%'/
         end) do