problem

problem

A golang library that implements application/problem+json

Features

• compatible with application/problem+json
• inspired by https://github.com/zalando/problem
• RFC link https://tools.ietf.org/html/rfc7807
• a Problem implements the Error interface and can be compared with errors.Is()
• Wrap an error to a Problem

Usage

problem.New(problem.Title("Not Found"), problem.Status(404)).JSONString()

Will produce this:

{
  "status": 404,
  "title": "Not Found"
}

You can also append some more options:

p := problem.New(problem.Title("Not Found"), problem.Status(404))
p.Append(problem.Detail("some more details"))

// Use the Marshaler interface to get the problem json as []byte
jsonBytes, err := json.Marshal(p)

// or simpler (ignores the error)
jsonBytes = p.JSON()

Custom key/values are also supported:

problem.New(problem.Title("Not Found"), problem.Custom("key", "value"))

To write the Problem directly to a http.ResponseWriter:

http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    problem.New(
      problem.Type("https://example.com/404"),
      problem.Status(404)
    ).WriteTo(w)
  })

If you are using gin you can simply reply the problem to the client:

func(c *gin.Context) {
  problem.New(
    problem.Title("houston! we have a problem"),
    problem.Status(http.StatusNotFound),
  ).WriteTo(c.Writer)
}

Creates a Problem from an existing error

  _, err := ioutil.ReadFile("non-existing")
  if err != nil {
    p := problem.New(
      problem.Wrap(err),
      problem.Title("Internal Error"),
      problem.Status(404),
      )
    if !errors.Is(p, os.ErrNotExist) {
      t.Fatalf("expected not existing error")
    }
  }