Add deserialisation for enum

spec/extensions/enum_spec.cr

@@ -65,6 +65,10 @@ module EnumSpec
       end
     end
 
+    it "can create from json", focus: true do
+      GenderType.from_json(%("male")).should eq(GenderType::Male)
+    end
+
     it "can export to json" do
       temporary do
         reinit!

src/clear/extensions/enum/enum.cr

@@ -1,3 +1,5 @@
+require "json"
+
 module Clear
   class IllegalEnumValueError < Exception
   end
@@ -28,6 +30,21 @@ module Clear
       super(x) || @value == x
     end
 
+    macro inherited
+      macro finished
+        # For Serialisation with JSON
+        def initialize(value : (::JSON::PullParser | String))
+          if value.is_a?(String)
+            @value = value
+          else
+            str = value.read_string
+            str.in?(self.class.authorized_values) || raise ::Clear::IllegalEnumValueError.new("Illegal enum value for `#{self.class}`: '#{str}'")
+            @value = str
+          end
+        end
+      end
+    end
+
     module Converter(T)
       def self.to_column(x) : T?
         case x
@@ -93,6 +110,9 @@ module Clear
   # MyApp::Gender.from_string("male")    # < return MyApp::Gender::Male
   # MyApp::Gender.from_string("unknown") # < throw Clear::IllegalEnumValueError
   #
+  # (De)serialisation is also supported
+  # MyApp::Gender.from_json("male")    # < return MyApp::Gender::Male
+  #
   # MyApp::Gender.valid?("female")  # < Return true
   # MyApp::Gender.valid?("unknown") # < Return false
   # ```