Merge pull request #406 from frou/doc-registertagnamefunc

Document RegisterTagNameFunc more

validator_instance.go

@@ -119,8 +119,17 @@ func (v *Validate) SetTagName(name string) {
 	v.tagName = name
 }
 
-// RegisterTagNameFunc registers a function to get another name from the
-// StructField eg. the JSON name
+// RegisterTagNameFunc registers a function to get alternate names for StructFields.
+//
+// eg. to use the names which have been specified for JSON representations of structs, rather than normal Go field names:
+//
+//    validate.RegisterTagNameFunc(func(fld reflect.StructField) string {
+//        name := strings.SplitN(fld.Tag.Get("json"), ",", 2)[0]
+//        if name == "-" {
+//            return ""
+//        }
+//        return name
+//    })
 func (v *Validate) RegisterTagNameFunc(fn TagNameFunc) {
 	v.tagNameFunc = fn
 	v.hasTagNameFunc = true