package module
v1.3.0 Latest Latest

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Published: Aug 30, 2019 License: MIT Imports: 2 Imported by: 0




A golang library that implements application/problem+json



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) {

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

func(c *gin.Context) {
    problem.Title("houston! we have a problem"),

Creates a Problem from an existing error

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




View Source
const (
	// ContentTypeJSON
	ContentTypeJSON = "application/problem+json"
	// ContentTypeXML
	ContentTypeXML = "application/problem+xml"


This section is empty.


This section is empty.


type Option

type Option interface {
	// contains filtered or unexported methods

An Option configures a Problem using the functional options paradigm popularized by Rob Pike.

func Custom

func Custom(key string, value interface{}) Option

Custom sets a custom key value

func Detail

func Detail(detail string) Option

Detail A human readable explanation specific to this occurrence of the problem.

func Instance

func Instance(uri string) Option

Instance an absolute URI that identifies the specific occurrence of the problem.

func Status

func Status(status int) Option

Status sets the HTTP status code generated by the origin server for this occurrence of the problem.

func Title

func Title(title string) Option

Title sets a title that appropriately describes it (think short) Written in english and readable for engineers (usually not suited for non technical stakeholders and not localized); example: Service Unavailable

func Type

func Type(uri string) Option

Type sets the type URI (typically, with the "http" or "https" scheme) that identifies the problem type. When dereferenced, it SHOULD provide human-readable documentation for the problem type

func Wrap added in v1.3.0

func Wrap(err error) Option

Wrap an error to the Problem

type Problem

type Problem struct {
	// contains filtered or unexported fields

func New

func New(opts ...Option) *Problem

New generates a new Problem

func (*Problem) Append

func (p *Problem) Append(opts ...Option) *Problem

Append an Option to a existing Problem

func (Problem) Error added in v1.3.0

func (p Problem) Error() string

Error implements the error interface, so a Problem can be used as an error

func (Problem) Is added in v1.3.0

func (p Problem) Is(err error) bool

Is compares Problem.Error() with err.Error()

func (Problem) JSON

func (p Problem) JSON() []byte

JSON returns the Problem as json bytes

func (Problem) JSONString

func (p Problem) JSONString() string

JSONString returns the Problem as json string

func (Problem) MarshalJSON added in v1.2.0

func (p Problem) MarshalJSON() ([]byte, error)

MarshalJSON implements the json.Marshaler interface

func (Problem) UnmarshalJSON added in v1.3.0

func (p Problem) UnmarshalJSON(b []byte) error

UnmarshalJSON implements the json.Unmarshaler interface

func (Problem) Unwrap added in v1.3.0

func (p Problem) Unwrap() error

Unwrap returns the result of calling the Unwrap method on err, if err implements Unwrap. Otherwise, Unwrap returns nil.

func (Problem) WriteTo added in v1.1.0

func (p Problem) WriteTo(w http.ResponseWriter) (int, error)

WriteTo writes the Problem to a http Response Writer

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