tagly

tagly

GoLang tag toolbox

This library is compatible with Go 1.17+

Please refer to CHANGELOG.md if you encounter breaking changes.

• Motivation
• Usage
• Contribution
• License

Motivation

This project provides go struct tag utility to parse complex tags, alongside common tag functionality, which includes a format tag

Usage

Formatting tag

package example

import (
	"reflect"
	"time"
	"log"
	"fmt"
	"github.com/viant/tagly/format"
)

type (
	Bar struct {
		Info string
	}
	Dummy struct {
		ID       string    `format:"Id"`
		At       time.Time `format:"tz=UTC,dateFormat=YYYY-MM-DD hh:mm"`
		Internal bool      `format:"-"`
		Bar      `format:",inline"`
		AttrX    string `format:",caseFormat=upperdash"`
		Other    string `format:",inline,dateFormat=YYYY-MM-DD" json:"JsonCustomizedName"`
	}
)

func ExampleOfFormatTag() {
	tagValue := reflect.StructTag(`format:",inline,dateFormat=YYYY-MM-DD" json:"JsonCustomizedName"`)
	tag, err := format.Parse(tagValue, "json")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%+v\n", tag)
}    

Parsing tags

package example

import (
	"strings"
	"fmt"
	"github.com/viant/tagly/tags"
)

type Tag struct {
    Name string
	Setting1 string
	Repeated []string
	SettingN bool
	
}

func (t *Tag) updateTagKey(key, value string) error {
    switch strings.ToLower(key) {
        case "name":
			t.Name = value
		case "setting1":
            t.Setting1 = value
        case "settingn":
			t.SettingN = value == "true" || value == ""
		case "repeated":
			t.Repeated = strings.Split(strings.Trim(value, "{}"), ",")
		default:
			return fmt.Errorf("unsupported tag: %s", key)
    }
	return nil
}


func ParseTag(tagString string) *Tag {
	tag := &Tag{}
	values := tags.Values(tagString)
	name, values := values.Name()
	tag.Name = name
	_ = values.MatchPairs(tag.updateTagKey)
	return tag
}

Case formatter

package example

import (
	"fmt"
	"github.com/viant/tagly/format/text"
)


func ExampleCaseFormatter() {
	
    caseFormat := text.CaseFormatUpperUnderscore
    formatter := caseFormat.To(text.CaseFormatLowerCamel)
    formatted := formatter.Format("THIS_IS_TEST")
    fmt.Printf("formatted: %s\n", formatted)
	
   detected := text.DetectCaseFormat("candidate", "candidate_2")
   fmt.Printf("detected: %s %v\n", detected, detected.IsDefined())
   
}

Numeric segments are preserved during case conversion, including after underscores. For example, converting to lower camel case produces:

Compatibility note: earlier versions could drop the last digit after a separator, producing names such as sampleSeen_Day or sampleSeen_1Day. Applications that use formatted names as JSON keys must coordinate adoption with their clients. Regenerate any explicit JSON tags derived from the affected names when upgrading.

Common tag:

• fomat tag: tag to define output format

Contributing to tagly

tagly is an open source project and contributors are welcome!

See TODO list

License

The source code is made available under the terms of the Apache License, Version 2, as stated in the file LICENSE.

Individual files may be made available under their own specific license, all compatible with Apache License, Version 2. Please see individual files for details.

Credits and Acknowledgements

Library Author: Adrian Witas