jerror

Package jerror is a helper to create errors. It supports creating parametrized messages to give more information on the error and easier way of wrapping. These errors are compatible with standard errors.Is and errors.Unwrap.

Example:

ErrCannotOpen := jerror.New("can not open file %s")

fileName := "file.txt"
err := os.Open(fileName)
if err != nil {
    return ErrCannotOpen.New().Args(fileName).Wrap(err)
}

It also generates a stack trace when the error is created, so you can see where the error was created.

ErrExample := jerror.New("error")
err := ErrExample.New()
spew.Dump(err.Frames())
// ([]jerror.Frame) (len=3 cap=4) {
//  (jerror.Frame) {
//   Function: (string) (len=35) "github.com/jfontan/jerror.TestStack",
//   File: (string) (len=44) "/home/jfontan/projects/jerror/jerror_test.go",
//   Line: (int) 97
//  },
//  (jerror.Frame) {
//   Function: (string) (len=15) "testing.tRunner",
//   File: (string) (len=34) "/usr/lib/go/src/testing/testing.go",
//   Line: (int) 1689
//  },
//  (jerror.Frame) {
//   Function: (string) (len=14) "runtime.goexit",
//   File: (string) (len=35) "/usr/lib/go/src/runtime/asm_amd64.s",
//   Line: (int) 1695
//  }
// }

You can set and retrieve values to a base error:

jerr := jerror.New("jerror example")
err := jerr.Set("key", "value")
val, _ := err.GetString("key")
fmt.Println(val)
// value

It can also generate slog compatible attributes to log the error and of there is older errors it also gives information about the oldest error:

jerr2 := jerror.New("jerror 2").Set("key", "value 2")
jerr1 := jerror.New("jerror 1").Set("key", "value 1").Wrap(jerr2)

var buf bytes.Buffer
log := slog.New(slog.NewJSONHandler(&buf, &slog.HandlerOptions{}))
log.Error("message", jerr1.SlogAttributes("data", true))

var j any
_ = json.Unmarshal(buf.Bytes(), &j)
i, _ := json.MarshalIndent(j, "", "  ")
fmt.Println(string(i))
// {
//   "data": {
//     "error": "jerror 1: jerror 2",
//     "last_jerror": {
//       "error": "jerror 2",
//       "stack": {
//         "0": "github.com/jfontan/jerror/examples.TestSlog github.com/jfontan/jerror/examples/examples_test.go:14",
//         "1": "testing.tRunner testing/testing.go:1689",
//         "2": "runtime.goexit runtime/asm_amd64.s:1695"
//       },
//       "values": {
//         "key": "value 2"
//       }
//     },
//     "stack": {
//       "0": "github.com/jfontan/jerror/examples.TestSlog github.com/jfontan/jerror/examples/examples_test.go:15",
//       "1": "testing.tRunner testing/testing.go:1689",
//       "2": "runtime.goexit runtime/asm_amd64.s:1695"
//     },
//     "values": {
//       "key": "value 1"
//     }
//   },
//   "level": "ERROR",
//   "msg": "message",
//   "time": "2024-05-30T16:26:33.292105723+02:00"
// }