Problem details implementation (https://tools.ietf.org/html/rfc7807) package for go.

go get github.com/mvmaasakkers/go-problemdetails

The ProblemDetails struct can be used as error because it implements the error interface. The ProblemType interface can be used to create predefined ProblemDetails with extensions and also implements the error interface.

The struct is setup to be used by the json and xml marshaler from the stdlib and will marshal into application/problem+json or application/problem+xml compliant data as defined in the RFC 7807.

To generate a ProblemDetails based on just a HTTP Status Code you can create one using NewHTTP(statusCode int):

problemDetails := problemdetails.NewHTTP(http.StatusNotFound)

This will generate a ProblemDetails struct that marshals as follows:

{
  "type": "about:blank",
  "title": "Not Found",
  "status": 404
}

<problem xmlns="urn:ietf:rfc:7807">
    <type>about:blank</type>
    <title>Not Found</title>
    <status>404</status>
</problem>

or use the more verbose New(statusCode int, problemType, title, detail, instance string):

problemDetails := problemdetails.New(http.StatusNotFound, "https://example.net/problem/object_not_found", "Object not found", "Object with id 1234 was not found, another id should be given.", "https://api.example.net/objects/1234")

This will generate a ProblemDetails struct that marshals as follows:

{
  "type": "https://example.net/problem/object_not_found",
  "title": "Object not found",
  "status": 404,
  "detail": "Object with id 1234 was not found, another id should be given.",
  "instance": "https://api.example.net/objects/1234"
}

<problem xmlns="urn:ietf:rfc:7807">
    <type>https://example.net/problem/object_not_found</type>
    <title>Object not found</title>
    <status>404</status>
    <detail>Object with id 1234 was not found, another id should be given.</detail>
    <instance>https://api.example.net/objects/1234</instance>
</problem>

For ease of use there are two output handlers available. ProblemDetails.ServeJSON for JSON and ProblemDetails.ServeXML for XML.

A shorthand for generating a 404 statuscode in Problem Details JSON to the ResponseWriter you can:

problemdetails.NewHTTP(http.StatusNotFound).ServeJSON(w, r)