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https://github.com/earthboundkid/resperr

Go package to associate status codes and messages with errors
https://github.com/earthboundkid/resperr

error-handling go http

Last synced: 3 months ago
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Go package to associate status codes and messages with errors

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# resperr [![GoDoc](https://godoc.org/github.com/carlmjohnson/resperr?status.svg)](https://godoc.org/github.com/carlmjohnson/resperr) [![Go Report Card](https://goreportcard.com/badge/github.com/carlmjohnson/resperr)](https://goreportcard.com/report/github.com/carlmjohnson/resperr) [![Calver v0.YY.Minor](https://img.shields.io/badge/calver-v0.YY.Minor-22bfda.svg)](https://calver.org)

Resperr is a Go package to associate status codes and messages with errors.

## Example usage

See [blog post](https://blog.carlmjohnson.net/post/2020/working-with-errors-as/) for a full description or [read the test code](https://github.com/carlmjohnson/resperr/blob/master/example_test.go) for more context:

```go
// write a simple handler that just checks for errors
// and replies with an error object if it gets one

func myHandler(w http.ResponseWriter, r *http.Request) {
// ... check user permissions...
if err := hasPermissions(r); err != nil {
replyError(w, r, err)
return
}
// ...validate request...
n, err := getItemNoFromRequest(r)
if err != nil {
replyError(w, r, err)
return
}
// ...get the data ...
item, err := getItemByNumber(n)
if err != nil {
replyError(w, r, err)
return
}
replyJSON(w, r, http.StatusOK, item)
}

// in the functions that your handler calls
// use resp err to associate different error conditions
// with appropriate HTTP status codes

func getItemByNumber(n int) (item *Item, err error) {
item, err = dbCall("...", n)
if err == sql.ErrNoRows {
// this is an anticipated 404
return nil, resperr.New(
http.StatusNotFound,
"%d not found", n)
}
if err != nil {
// this is an unexpected 500!
return nil, err
}
// ...
return
}

// you can also return specific messages for users as needed

func getItemNoFromRequest(r *http.Request) (int, error) {
ns := r.URL.Query().Get("n")
if ns == "" {
return 0, resperr.WithUserMessage(
resperr.New(
http.StatusBadRequest,
"missing ?n= in query"),
"Please enter a number.")
}
n, err := strconv.Atoi(ns)
if err != nil {
return 0, resperr.WithCodeAndMessage(
err, http.StatusBadRequest,
"Input is not a number.")
}
return n, nil
}

func hasPermissions(r *http.Request) error {
// lol, don't do this!
user := r.URL.Query().Get("user")
if user == "admin" {
return nil
}
return resperr.New(http.StatusForbidden,
"bad user %q", user)
}
```