distribution/registry/api/errcode/errors.go
Doug Davis 94e2e9f4a0 Add ability to pass in substitution args into an Error
Signed-off-by: Doug Davis <dug@us.ibm.com>
2015-07-15 11:02:10 -07:00

253 lines
6.2 KiB
Go

package errcode
import (
"encoding/json"
"fmt"
"strings"
)
// ErrorCoder is the base interface for ErrorCode and Error allowing
// users of each to just call ErrorCode to get the real ID of each
type ErrorCoder interface {
ErrorCode() ErrorCode
}
// ErrorCode represents the error type. The errors are serialized via strings
// and the integer format may change and should *never* be exported.
type ErrorCode int
// ErrorCode just returns itself
func (ec ErrorCode) ErrorCode() ErrorCode {
return ec
}
// Error returns the ID/Value
func (ec ErrorCode) Error() string {
return ec.Descriptor().Value
}
// Descriptor returns the descriptor for the error code.
func (ec ErrorCode) Descriptor() ErrorDescriptor {
d, ok := errorCodeToDescriptors[ec]
if !ok {
return ErrorCodeUnknown.Descriptor()
}
return d
}
// String returns the canonical identifier for this error code.
func (ec ErrorCode) String() string {
return ec.Descriptor().Value
}
// Message returned the human-readable error message for this error code.
func (ec ErrorCode) Message() string {
return ec.Descriptor().Message
}
// MarshalText encodes the receiver into UTF-8-encoded text and returns the
// result.
func (ec ErrorCode) MarshalText() (text []byte, err error) {
return []byte(ec.String()), nil
}
// UnmarshalText decodes the form generated by MarshalText.
func (ec *ErrorCode) UnmarshalText(text []byte) error {
desc, ok := idToDescriptors[string(text)]
if !ok {
desc = ErrorCodeUnknown.Descriptor()
}
*ec = desc.Code
return nil
}
// WithDetail creates a new Error struct based on the passed-in info and
// set the Detail property appropriately
func (ec ErrorCode) WithDetail(detail interface{}) Error {
return Error{
Code: ec,
Message: ec.Message(),
}.WithDetail(detail)
}
// WithArgs creates a new Error struct and sets the Args slice
func (ec ErrorCode) WithArgs(args ...interface{}) Error {
return Error{
Code: ec,
Message: ec.Message(),
}.WithArgs(args...)
}
// Error provides a wrapper around ErrorCode with extra Details provided.
type Error struct {
Code ErrorCode `json:"code"`
Message string `json:"message"`
Detail interface{} `json:"detail,omitempty"`
// TODO(duglin): See if we need an "args" property so we can do the
// variable substitution right before showing the message to the user
}
// ErrorCode returns the ID/Value of this Error
func (e Error) ErrorCode() ErrorCode {
return e.Code
}
// Error returns a human readable representation of the error.
func (e Error) Error() string {
return fmt.Sprintf("%s: %s",
strings.ToLower(strings.Replace(e.Code.String(), "_", " ", -1)),
e.Code.Message())
}
// WithDetail will return a new Error, based on the current one, but with
// some Detail info added
func (e Error) WithDetail(detail interface{}) Error {
return Error{
Code: e.Code,
Message: e.Message,
Detail: detail,
}
}
// WithArgs uses the passed-in list of interface{} as the substitution
// variables in the Error's Message string, but returns a new Error
func (e Error) WithArgs(args ...interface{}) Error {
return Error{
Code: e.Code,
Message: fmt.Sprintf(e.Code.Message(), args...),
Detail: e.Detail,
}
}
// ErrorDescriptor provides relevant information about a given error code.
type ErrorDescriptor struct {
// Code is the error code that this descriptor describes.
Code ErrorCode
// Value provides a unique, string key, often captilized with
// underscores, to identify the error code. This value is used as the
// keyed value when serializing api errors.
Value string
// Message is a short, human readable decription of the error condition
// included in API responses.
Message string
// Description provides a complete account of the errors purpose, suitable
// for use in documentation.
Description string
// HTTPStatusCode provides the http status code that is associated with
// this error condition.
HTTPStatusCode int
}
// ParseErrorCode returns the value by the string error code.
// `ErrorCodeUnknown` will be returned if the error is not known.
func ParseErrorCode(value string) ErrorCode {
ed, ok := idToDescriptors[value]
if ok {
return ed.Code
}
return ErrorCodeUnknown
}
// Errors provides the envelope for multiple errors and a few sugar methods
// for use within the application.
type Errors []error
func (errs Errors) Error() string {
switch len(errs) {
case 0:
return "<nil>"
case 1:
return errs[0].Error()
default:
msg := "errors:\n"
for _, err := range errs {
msg += err.Error() + "\n"
}
return msg
}
}
// Len returns the current number of errors.
func (errs Errors) Len() int {
return len(errs)
}
// MarshalJSON converts slice of error, ErrorCode or Error into a
// slice of Error - then serializes
func (errs Errors) MarshalJSON() ([]byte, error) {
var tmpErrs struct {
Errors []Error `json:"errors,omitempty"`
}
for _, daErr := range errs {
var err Error
switch daErr.(type) {
case ErrorCode:
err = daErr.(ErrorCode).WithDetail(nil)
case Error:
err = daErr.(Error)
default:
err = ErrorCodeUnknown.WithDetail(daErr)
}
// If the Error struct was setup and they forgot to set the
// Message field (meaning its "") then grab it from the ErrCode
msg := err.Message
if msg == "" {
msg = err.Code.Message()
}
tmpErrs.Errors = append(tmpErrs.Errors, Error{
Code: err.Code,
Message: msg,
Detail: err.Detail,
})
}
return json.Marshal(tmpErrs)
}
// UnmarshalJSON deserializes []Error and then converts it into slice of
// Error or ErrorCode
func (errs *Errors) UnmarshalJSON(data []byte) error {
var tmpErrs struct {
Errors []Error
}
if err := json.Unmarshal(data, &tmpErrs); err != nil {
return err
}
var newErrs Errors
for _, daErr := range tmpErrs.Errors {
// If Message is empty or exactly matches the Code's message string
// then just use the Code, no need for a full Error struct
if daErr.Detail == nil && (daErr.Message == "" || daErr.Message == daErr.Code.Message()) {
// Error's w/o details get converted to ErrorCode
newErrs = append(newErrs, daErr.Code)
} else {
// Error's w/ details are untouched
newErrs = append(newErrs, Error{
Code: daErr.Code,
Message: daErr.Message,
Detail: daErr.Detail,
})
}
}
*errs = newErrs
return nil
}