structtag 
structtag provides an easy way of parsing and manipulating struct tag fields.
Please vendor the library as it might change in future versions.
Install
go get github.com/fatih/structtag
Example
package main
import (
"fmt"
"reflect"
"sort"
"github.com/fatih/structtag"
)
func main() {
type t struct {
t string `json:"foo,omitempty,string" xml:"foo"`
}
// get field tag
tag := reflect.TypeOf(t{}).Field(0).Tag
// ... and start using structtag by parsing the tag
tags, err := structtag.Parse(string(tag))
if err != nil {
panic(err)
}
// iterate over all tags
for _, t := range tags.Tags() {
fmt.Printf("tag: %+v\n", t)
}
// get a single tag
jsonTag, err := tags.Get("json")
if err != nil {
panic(err)
}
fmt.Println(jsonTag) // Output: json:"foo,omitempty,string"
fmt.Println(jsonTag.Key) // Output: json
fmt.Println(jsonTag.Name) // Output: foo
fmt.Println(jsonTag.Options) // Output: [omitempty string]
// change existing tag
jsonTag.Name = "foo_bar"
jsonTag.Options = nil
tags.Set(jsonTag)
// add new tag
tags.Set(&structtag.Tag{
Key: "hcl",
Name: "foo",
Options: []string{"squash"},
})
// print the tags
fmt.Println(tags) // Output: json:"foo_bar" xml:"foo" hcl:"foo,squash"
// sort tags according to keys
sort.Sort(tags)
fmt.Println(tags) // Output: hcl:"foo,squash" json:"foo_bar" xml:"foo"
}