add JSON encode and decode

lib/liquid/standardfilters.rb

@@ -3,6 +3,7 @@
 require 'cgi'
 require 'base64'
 require 'bigdecimal'
+require 'json'
 
 module Liquid
   module StandardFilters
@@ -99,6 +100,30 @@ module Liquid
       input.to_s.gsub(HTML_ESCAPE_ONCE_REGEXP, HTML_ESCAPE)
     end
 
+    # @liquid_public_docs
+    # @liquid_type filter
+    # @liquid_category string
+    # @liquid_summary
+    #   JSON encodes the input.
+    # @liquid_syntax variable | json_encode.
+    # @liquid_return [string]
+    def json_encode(input)
+      JSON.generate(input)
+    end
+
+    # @liquid_public_docs
+    # @liquid_type filter
+    # @liquid_category string
+    # @liquid_summary
+    #   JSON decodes an input.
+    # @liquid_syntax string | json_decode.
+    # @liquid_return [string]
+    def json_decode(input)
+      JSON.parse(input.to_s) unless input.nil?
+    rescue JSON::ParserError, TypeError => e
+      raise Liquid::ArgumentError, e.message
+    end
+
     # @liquid_public_docs
     # @liquid_type filter
     # @liquid_category string

test/integration/standard_filter_test.rb

@@ -170,6 +170,30 @@ class StandardFiltersTest < Minitest::Test
     assert_equal('&lt;strong&gt;Hulk&lt;/strong&gt;', @filters.escape_once('&lt;strong&gt;Hulk</strong>'))
   end
 
+  def test_json_encode
+    assert_equal('{"name":"Fizz Buzz","id":1235}', @filters.json_encode({"name"=>"Fizz Buzz", "id"=>1235}))
+    assert_equal('[1,2,3,5]', @filters.json_encode([1, 2, 3, 5]))
+
+    assert_equal("null", @filters.json_encode(nil))
+    assert_equal("1", @filters.json_encode(1))
+  end
+
+  def test_json_decode
+    assert_equal({"name"=>"Fizz Buzz", "id"=>1235}, @filters.json_decode('{"name":"Fizz Buzz","id":1235}'))
+
+    assert_template_result('{"foo"=>{"bar"=>[1, 2, 3]}}', '{% assign json_result = json_data | json_decode %}{{ json_result }}', {"json_data" => '{"foo":{"bar":[1,2,3]}}'})
+    assert_template_result('{"bar"=>[1, 2, 3]}', '{% assign json_result = json_data | json_decode %}{{ json_result.foo }}', {"json_data" => '{"foo":{"bar":[1,2,3]}}'})
+    assert_template_result('123', '{% assign json_result = json_data | json_decode %}{{ json_result.foo.bar }}', {"json_data" => '{"foo":{"bar":[1,2,3]}}'})
+    assert_template_result('123', '{% assign json_result = json_data | json_decode %}{{ json_result.foo["bar"] }}', {"json_data" => '{"foo":{"bar":[1,2,3]}}'})
+    assert_template_result('1', '{% assign json_result = json_data | json_decode %}{{ json_result.foo.bar[0] }}', {"json_data" => '{"foo":{"bar":[1,2,3]}}'})
+
+    assert_equal(1, @filters.json_decode(1))
+    assert_nil(@filters.json_decode(nil))
+    assert_raises(Liquid::ArgumentError) do
+      @filters.json_decode('{"name":"BrokenFragment')
+    end
+  end
+
   def test_base64_encode
     assert_equal('b25lIHR3byB0aHJlZQ==', @filters.base64_encode('one two three'))
     assert_equal('', @filters.base64_encode(nil))