Added basic JSON column support

spec/db_spec.cr

@@ -53,6 +53,7 @@ DB::DriverSpecs(MySql::Any).run do
       sample_value Time.utc(2016, 2, 15, 10, 15, 30, nanosecond: 543_012_000), "timestamp(6)", "TIMESTAMP '2016-02-15 10:15:30.543012'"
       sample_value Time::Span.new(0, 10, 15, 30, nanoseconds: 543_000_000), "Time(3)", "TIME '10:15:30.543'"
       sample_value Time::Span.new(0, 10, 15, 30, nanoseconds: 543_012_000), "Time(6)", "TIME '10:15:30.543012'"
+      sample_value JSON::Any.new({"example" => JSON::Any.new("json")}), "JSON", "'{\"example\": \"json\"}'", type_safe_value: false
     end
   end
 

src/mysql.cr

@@ -1,4 +1,5 @@
 require "db"
+require "json"
 require "./mysql/*"
 
 module MySql
@@ -10,7 +11,7 @@ module MySql
     end
   end
 
-  alias Any = DB::Any | Int16 | Int8 | Time::Span
+  alias Any = DB::Any | Int16 | Int8 | Time::Span | JSON::Any
 
   # :nodoc:
   TIME_ZONE = Time::Location::UTC

src/mysql/types.cr

@@ -1,3 +1,5 @@
+require "json"
+
 # :nodoc:
 abstract struct MySql::Type
   # Column types
@@ -60,6 +62,10 @@ abstract struct MySql::Type
     MySql::Type::Null
   end
 
+  def self.type_for(t : ::JSON::Any.class)
+    MySql::Type::Json
+  end
+
   def self.type_for(t)
     raise "MySql::Type does not support #{t} values"
   end
@@ -144,6 +150,7 @@ abstract struct MySql::Type
       nil
     end
   end
+
   decl_type Timestamp, 0x07u8, ::Time do
     def self.write(packet, v : ::Time)
       MySql::Type::DateTime.write(packet, v)
@@ -351,4 +358,28 @@ abstract struct MySql::Type
     end
   end
   decl_type Geometry, 0xffu8
+
+  # Parse the JSON column type
+  decl_type Json, 245_u8, JSON::Any do
+    def self.write(packet, v : String)
+      packet.write_lenenc_string v
+    end
+
+    def self.write(packet, v : ::JSON::Any)
+      packet.write_lenenc_string v.to_json
+    end
+
+    def self.read(packet)
+      str = packet.read_lenenc_string.lchop("\u0013")
+      JSON.parse(str)
+    rescue e
+      nil
+    end
+
+    def self.parse(str : ::String)
+      JSON.parse(str)
+    rescue e
+      nil
+    end
+  end
 end