Access to StructField object in FieldError

[mbretter]

• [x] I have looked at the documentation here first?
• [x] I have looked at the examples provided that may showcase my question here?

Package version eg. v9, v10:

v10

Issue, Question or Enhancement:

It would be great having direct access to the struct field object inside FieldError, at the moment the StructField() func just returns the name of the field. Something like RawStructField() StructField would help a lot when retrieving additional infos from the struct field like additional tags when doing the error handling.

Code sample, to showcase or reproduce:

type Address struct {
    Street string `json:"street" validate:"required" error:"required:global.street.required"`
}

err := validate.Struct(loginData)
if err != nil {
for _, err := range err.(validator.ValidationErrors) {

              fld := err.RawStructField()
              errStr := fld.Tag.Get("error")
              // do custom error handling, messages, etc
        }
}

[ardrabczyk]

Just want to say that of course you can do it yourself:

package main

import (
        "log"
        "reflect"

        "github.com/go-playground/validator"
)

type MySettings struct {
        Url      string `validate:"required,url" err:"url it must be non empty and must be correct URL"`
        Username string `validate:"required" err:"username must be non empty"`
        Password string `validate:"required" err:"password must be non empty"`
}

func main() {
        settings := MySettings{}
        validate := validator.New()
        if err := validate.Struct(&settings); err != nil {
                for _, err := range err.(validator.ValidationErrors) {
                        fld := reflect.ValueOf(settings).Type()
                        a, _ := fld.FieldByName(err.Field())
                        log.Println("errorstr ==", a.Tag.Get("err"))
                }
        }
}

Output will be:

2023/12/18 09:05:34 errorstr == url it must be non empty and must be correct URL
2023/12/18 09:05:34 errorstr == username must be non empty
2023/12/18 09:05:34 errorstr == password must be non empty

And now there is also this https://github.com/go-playground/validator/pull/1183.

[mbretter]

Does this work for nested fields, if err.Field() is something like "Foo.Bar"?

[mbretter]

atm I have to seek through the whole struct, with something like:

p := strings.Split(err.StructNamespace(), ".") // struct field name path, e.g. Foo.Bar
p = p[1:]
fld := getStructField(t, p)
...
func getStructField(s reflect.Type, path []string) *reflect.StructField {
    var field reflect.StructField

    t := s
    for _, p := range path {
        if t.Kind() == reflect.Ptr {
            t = t.Elem()
        }

        f, ok := t.FieldByName(p)
        if ok {
            field = f
            t = f.Type
        }
    }

    return &field
}