Go code generator for Capnproto definitions. It integrates MsgPack and Capn'proto code generators. Code generation options available as annotations. Also this tool adds support for possible data validation.

HOW TO

You need Go 1.5 version. Set environment variable: GO15VENDOREXPERIMENT=1.

1. Install capnp tool. See Instructions

2. Install caps

   go get github.com/tpukep/caps/...

3. Write Capn'proto schema model.capnp:

   @0xad8d3cbc6db52a1d;
   
   using Go = import "/go.capnp";
   $Go.package("model");
   
   struct Book {
      title      @0:   Text;
      pageCount  @1:   Int32;
      authors    @2:   List(Text);
      content    @3:   Text;
   }

4. Generate Go plain code.

   caps -source model.capnp

Annotations

Codecs

using Codec = import "/caps/codec.capnp";

# By default only plain Go code will be generated
# These annotations are enable extra features

$Codec.msgp;  # Enables msgp code generation
$Codec.json;  # Enables go json tags generation in plain Go code
$Codec.capnp; # Enables Capn'proto code generation

struct Person {
   name  @0 :Text;
   email @1 :Text;
   age   @2 :UInt8;
   phone @3 :Text;
}

Fields

using Field = import "/caps/field.capnp";

struct Person {
   firstName  @0 :Text $Field.required("name"); # Rename field to use more
                                                # compact name in serialization code
   email @1 :Text;
   age   @2 :UInt8 $Field.optional("pc");      # Mark as optional
   phone @3 :Text $Field.ignored;              # This field will be ignored
}

Checks

You can use Go-playground Validator expressions to generate tags in plain Go code. Note that $Field tags also generate corresponding validate tags.

Example of various checks

using Check = import "/caps/check.capnp";

struct Person $Go.doc("Some Person") {
   name  @0 :Text  $Check.value("max=256,min=2");
   email @1 :Text  $Check.value("email");
   age   @2 :UInt8 $Check.value("max=40");
   phone @3 :Text;
}

Examples of use located at demo/annotations.capnp.