jtd

JTD to Go Generator

A JSON Type Definition (RFC 8927) to Go code generator.

Installation

go install github.com/delaneyj/toolbelt/jtd/cmd/jtd2go@latest

Usage

jtd2go -input schema.json -output types.go -package myapp

Options

• -input: Input JTD schema file (required)
• -output: Output Go file (default: stdout)
• -package: Go package name (default: "types")
• -comments: Generate comments from descriptions (default: true)
• -validate: Generate validation methods (default: false)
• -help: Show help

Features

Supported JTD Forms

• Type forms: All RFC 8927 primitive types

  • boolean → bool
  • string → string
  • timestamp → time.Time
  • float32, float64 → float32, float64
  • int8, int16, int32 → int8, int16, int32
  • uint8, uint16, uint32 → uint8, uint16, uint32

• Enum form: String enumerations → Go constants

• Elements form: Arrays → Go slices

• Properties form: Objects → Go structs

• Values form: Maps → Go maps

• Discriminator form: Tagged unions → Go interfaces

• Ref form: Schema references

• Empty form: Any type → any

Additional Features

• Nullable types using pointers
• Optional struct fields with omitempty tags
• Metadata descriptions as Go comments
• Validation method generation
• Proper handling of circular references

Examples

Simple Schema

{
  "properties": {
    "name": { "type": "string" },
    "age": { "type": "int32" }
  }
}

Generates:

type Root struct {
    Name string `json:"name"`
    Age  int32  `json:"age"`
}

Enum Schema

{
  "definitions": {
    "status": {
      "enum": ["active", "inactive", "pending"]
    }
  }
}

Generates:

type Status string

const (
    StatusActive   Status = "active"
    StatusInactive Status = "inactive"
    StatusPending  Status = "pending"
)

Discriminated Union

{
  "definitions": {
    "shape": {
      "discriminator": "type",
      "mapping": {
        "circle": {
          "properties": {
            "radius": { "type": "float64" }
          }
        },
        "rectangle": {
          "properties": {
            "width": { "type": "float64" },
            "height": { "type": "float64" }
          }
        }
      }
    }
  }
}

Generates:

type Shape interface {
    isShape()
    Type() string
}

type ShapeCircle struct {
    Type   string  `json:"type"`
    Radius float64 `json:"radius"`
}

func (ShapeCircle) isShape() {}
func (v ShapeCircle) Type() string { return v.Type }

type ShapeRectangle struct {
    Type   string  `json:"type"`
    Width  float64 `json:"width"`
    Height float64 `json:"height"`
}

func (ShapeRectangle) isShape() {}
func (v ShapeRectangle) Type() string { return v.Type }

Testing

go test ./jtd

License

Same as the parent toolbelt project.