Allow setting empty sorts (#1549)

Co-authored-by: Greg Molnar <[email protected]>

Author: yujideveloper

lib/ransack/nodes/sort.rb

@@ -8,7 +8,7 @@ class Sort < Node
 
       class << self
         def extract(context, str)
-          return unless str
+          return if str.blank?
           attr, direction = str.split(/\s+/, 2)
           self.new(context).build(name: attr, dir: direction)
         end

lib/ransack/search.rb

@@ -69,7 +69,7 @@ def sorts=(args)
           else
             sort = Nodes::Sort.extract(@context, sort)
           end
-          self.sorts << sort
+          self.sorts << sort if sort
         end
       when Hash
         args.each do |index, attrs|

spec/ransack/search_spec.rb

@@ -479,6 +479,11 @@ def remove_quotes_and_backticks(str)
         @s = Search.new(Person)
       end
 
+      it 'doesn\'t creates sorts' do
+        @s.sorts = ''
+        expect(@s.sorts.size).to eq(0)
+      end
+
       it 'creates sorts based on a single attribute/direction' do
         @s.sorts = 'id desc'
         expect(@s.sorts.size).to eq(1)