✨ Add JSON marshalling

errorf.go

@@ -1,6 +1,7 @@
 package errors
 
 import (
+	"encoding/json"
 	"fmt"
 	"net/http"
 )
@@ -16,13 +17,14 @@ import (
 //
 //	err := errors.Errorf(http.StatusNotFound, "%w", sqlError).SetMsg("user not found %d", userId)
 func Errorf(status int, format string, parts ...any) SettableError {
+	meta := make(map[string]any)
 	if len(parts) == 0 {
-		return &erf{status, format, ""}
+		return &erf{status, format, "", meta}
 	}
 
 	err := fmt.Errorf(format, parts...)
 	msg := err.Error()
-	er := &erf{status, msg, ""}
+	er := &erf{status, msg, "", meta}
 	if we, ok := err.(wrappedError); ok {
 		return &wrapErr{er, we.Unwrap()}
 	}
@@ -34,11 +36,13 @@ func Errorf(status int, format string, parts ...any) SettableError {
 
 var _ ResponsableError = new(erf)
 var _ SettableError = new(erf)
+var _ json.Marshaler = new(erf)
 
 type erf struct {
 	stat int
 	err  string
 	msg  string
+	meta map[string]any
 }
 
 func (e *erf) Status() int {
@@ -76,6 +80,21 @@ func (e *erf) SetMsg(msg string, parts ...any) SettableError {
 	return e
 }
 
+func (e *erf) SetField(field string, value any) SettableError {
+	e.meta[field] = value
+	return e
+}
+
+func (e *erf) JSON() any {
+	m := e.meta
+	m["error"] = e.Msg()
+	return m
+}
+
+func (e *erf) MarshalJSON() ([]byte, error) {
+	return json.Marshal(e.JSON())
+}
+
 var _ UnwrappableError = new(wrapErr)
 
 type wrapErr struct {