Package nan - Zero allocation Nullable structures in one library with handy conversion functions, marshallers and unmarshallers.

Features:

• short name "nan"
• handy conversion functions
• select which marshalers you want and limit dependencies to only those you actually need
• ability to convert your custom structs to nan compatible type with Valid field and all requested encoders/decoders

Supported types:

• bool
• float32
• float64
• int
• int8
• int16
• int32
• int64
• string
• time.Time
• more types will be added as necessary

Supported marshallers:

• Standart JSON
• encoding.TextMarshaler/TextUnmarshaler. Reuses standard JSON logic and format
• jsoniter
• easyjson
• go-json
• Scylla and Cassandra. Compatible with gocql
• SQL

Simply create struct field or variable with one of the exported types and use it without any changes to external API.

JSON input/output will be converted to null or non null values. Scylla and Cassandra will use wire format compatible with gocql.

	var data struct {
		Code nan.NullString `json:"code"`
	}

	b, err := jsoniter.Marshal(data)
	if err != nil {
		panic(err)
	}

	// {"code":null}
	fmt.Println(string(b))

	data.Code = nan.String("1")
	// Or
	// data.Code = nan.NullString{String: "1", Valid: true}

	b, err = jsoniter.Marshal(data)
	if err != nil {
		panic(err)
	}

	// {"code":"1"}
	fmt.Println(string(b))

# go install github.com/kak-tus/nan/cmd/nan@latest
# nan -help

Instead of depending on the whole github.com/kak-tus/nan you can also use nan command to select which marshalers you want. Simply run nan with one or more arguments and it will generate implementations for the specified marshalers in the current directory. For example, running

# nan gen -json -jsoniter

will generate nan.go, json.go, jsoniter.go files in the current working directory that contain only encoding/json and jsoniter marshalers. Nothing else will be generated so you don't have to depend on all the marshalers that github.com/kak-tus/nan supports. Generated files will use current directory name as its package name. You can also specify your own package name with -pkg argument.

Imagine, that you have custom struct

type MyStruct struct {
	ID   int
	Name string
}

Use nan command on its file

# nan extra -json -jsoniter example/structs.go

This will generate *_nan.go near source files with json (or any other supported marshallers). And now you have nan compatible struct with all needed marshallers

var val MyStruct

nullVal := NanMyStruct(val)
// Or
// nullVal := NullMyStruct{MyStruct: val, Valid: true}

fmt.Println(nullVal.ID)

See example to specific of easyjson, cql, sql generation.

nan extra coommand supports any number of file names at command line.

See here.