Common juju errors and functions to annotate errors. Based on juju/errgo
Common juju errors and functions to annotate errors. Based on juju/errgo
import "github.com/juju/errors"
The juju/errors provides an easy way to annotate errors without losing the original error context.
The exported New and Errorf functions are designed to replace the
errors.New and fmt.Errorf functions respectively. The same underlying
error is there, but the package also records the location at which the error
was created.
A primary use case for this library is to add extra context any time an error is returned from a function.
if err := SomeFunc(); err != nil {
return err
}
This instead becomes:
if err := SomeFunc(); err != nil {
return errors.Trace(err)
}
which just records the file and line number of the Trace call, or
if err := SomeFunc(); err != nil {
return errors.Annotate(err, "more context")
}
which also adds an annotation to the error.
When you want to check to see if an error is of a particular type, a helper
function is normally exported by the package that returned the error, like the
os package does. The underlying cause of the error is available using the
Cause function.
os.IsNotExist(errors.Cause(err))
The result of the Error() call on an annotated error is the annotations joined
with colons, then the result of the Error() method for the underlying error
that was the cause.
err := errors.Errorf("original")
err = errors.Annotatef(err, "context")
err = errors.Annotatef(err, "more context")
err.Error() -> "more context: context: original"
Obviously recording the file, line and functions is not very useful if you cannot get them back out again.
errors.ErrorStack(err)
will return something like:
first error
github.com/juju/errors/annotation_test.go:193:
github.com/juju/errors/annotation_test.go:194: annotation
github.com/juju/errors/annotation_test.go:195:
github.com/juju/errors/annotation_test.go:196: more context
github.com/juju/errors/annotation_test.go:197:
The first error was generated by an external system, so there was no location associated. The second, fourth, and last lines were generated with Trace calls, and the other two through Annotate.
Sometimes when responding to an error you want to return a more specific error for the situation.
if err := FindField(field); err != nil {
return errors.Wrap(err, errors.NotFoundf(field))
}
This returns an error where the complete error stack is still available, and
errors.Cause() will return the NotFound error.
func AlreadyExistsf(format string, args ...interface{}) error
AlreadyExistsf returns an error which satisfies IsAlreadyExists().
func Annotate(other error, message string) error
Annotate is used to add extra context to an existing error. The location of the Annotate call is recorded with the annotations. The file, line and function are also recorded.
For example:
if err := SomeFunc(); err != nil {
return errors.Annotate(err, "failed to frombulate")
}
func Annotatef(other error, format string, args ...interface{}) error
Annotatef is used to add extra context to an existing error. The location of the Annotate call is recorded with the annotations. The file, line and function are also recorded.
For example:
if err := SomeFunc(); err != nil {
return errors.Annotatef(err, "failed to frombulate the %s", arg)
}
func BadRequestf(format string, args ...interface{}) error
BadRequestf returns an error which satisfies IsBadRequest().
func Cause(err error) error
Cause returns the cause of the given error. This will be either the original error, or the result of a Wrap or Mask call.
Cause is the usual way to diagnose errors that may have been wrapped by the other errors functions.
func DeferredAnnotatef(err *error, format string, args ...interface{})
DeferredAnnotatef annotates the given error (when it is not nil) with the given format string and arguments (like fmt.Sprintf). If *err is nil, DeferredAnnotatef does nothing. This method is used in a defer statement in order to annotate any resulting error with the same message.
For example:
defer DeferredAnnotatef(&err, "failed to frombulate the %s", arg)
func Details(err error) string
Details returns information about the stack of errors wrapped by err, in the format:
[{filename:99: error one} {otherfile:55: cause of error one}]
This is a terse alternative to ErrorStack as it returns a single line.
func ErrorStack(err error) string
ErrorStack returns a string representation of the annotated error. If the error passed as the parameter is not an annotated error, the result is simply the result of the Error() method on that error.
If the error is an annotated error, a multi-line string is returned where each line represents one entry in the annotation stack. The full filename from the call stack is used in the output.
first error
github.com/juju/errors/annotation_test.go:193:
github.com/juju/errors/annotation_test.go:194: annotation
github.com/juju/errors/annotation_test.go:195:
github.com/juju/errors/annotation_test.go:196: more context
github.com/juju/errors/annotation_test.go:197:
func Errorf(format string, args ...interface{}) error
Errorf creates a new annotated error and records the location that the error is created. This should be a drop in replacement for fmt.Errorf.
For example:
return errors.Errorf("validation failed: %s", message)
func Forbiddenf(format string, args ...interface{}) error
Forbiddenf returns an error which satistifes IsForbidden()
func IsAlreadyExists(err error) bool
IsAlreadyExists reports whether the error was created with AlreadyExistsf() or NewAlreadyExists().
func IsBadRequest(err error) bool
IsBadRequest reports whether err was created with BadRequestf() or NewBadRequest().
func IsForbidden(err error) bool
IsForbidden reports whether err was created with Forbiddenf() or NewForbidden().
func IsMethodNotAllowed(err error) bool
IsMethodNotAllowed reports whether err was created with MethodNotAllowedf() or NewMethodNotAllowed().
func IsNotAssigned(err error) bool
IsNotAssigned reports whether err was created with NotAssignedf() or NewNotAssigned().
func IsNotFound(err error) bool
IsNotFound reports whether err was created with NotFoundf() or NewNotFound().
func IsNotImplemented(err error) bool
IsNotImplemented reports whether err was created with NotImplementedf() or NewNotImplemented().
func IsNotProvisioned(err error) bool
IsNotProvisioned reports whether err was created with NotProvisionedf() or NewNotProvisioned().
func IsNotSupported(err error) bool
IsNotSupported reports whether the error was created with NotSupportedf() or NewNotSupported().
func IsNotValid(err error) bool
IsNotValid reports whether the error was created with NotValidf() or NewNotValid().
func IsUnauthorized(err error) bool
IsUnauthorized reports whether err was created with Unauthorizedf() or NewUnauthorized().
func IsUserNotFound(err error) bool
IsUserNotFound reports whether err was created with UserNotFoundf() or NewUserNotFound().
func Mask(other error) error
Mask hides the underlying error type, and records the location of the masking.
func Maskf(other error, format string, args ...interface{}) error
Mask masks the given error with the given format string and arguments (like fmt.Sprintf), returning a new error that maintains the error stack, but hides the underlying error type. The error string still contains the full annotations. If you want to hide the annotations, call Wrap.
func MethodNotAllowedf(format string, args ...interface{}) error
MethodNotAllowedf returns an error which satisfies IsMethodNotAllowed().
func New(message string) error
New is a drop in replacement for the standard library errors module that records the location that the error is created.
For example:
return errors.New("validation failed")
func NewAlreadyExists(err error, msg string) error
NewAlreadyExists returns an error which wraps err and satisfies IsAlreadyExists().
func NewBadRequest(err error, msg string) error
NewBadRequest returns an error which wraps err that satisfies IsBadRequest().
func NewForbidden(err error, msg string) error
NewForbidden returns an error which wraps err that satisfies IsForbidden().
func NewMethodNotAllowed(err error, msg string) error
NewMethodNotAllowed returns an error which wraps err that satisfies IsMethodNotAllowed().
func NewNotAssigned(err error, msg string) error
NewNotAssigned returns an error which wraps err that satisfies IsNotAssigned().
func NewNotFound(err error, msg string) error
NewNotFound returns an error which wraps err that satisfies IsNotFound().
func NewNotImplemented(err error, msg string) error
NewNotImplemented returns an error which wraps err and satisfies IsNotImplemented().
func NewNotProvisioned(err error, msg string) error
NewNotProvisioned returns an error which wraps err that satisfies IsNotProvisioned().
func NewNotSupported(err error, msg string) error
NewNotSupported returns an error which wraps err and satisfies IsNotSupported().
func NewNotValid(err error, msg string) error
NewNotValid returns an error which wraps err and satisfies IsNotValid().
func NewUnauthorized(err error, msg string) error
NewUnauthorized returns an error which wraps err and satisfies IsUnauthorized().
func NewUserNotFound(err error, msg string) error
NewUserNotFound returns an error which wraps err and satisfies IsUserNotFound().
func NotAssignedf(format string, args ...interface{}) error
NotAssignedf returns an error which satisfies IsNotAssigned().
func NotFoundf(format string, args ...interface{}) error
NotFoundf returns an error which satisfies IsNotFound().
func NotImplementedf(format string, args ...interface{}) error
NotImplementedf returns an error which satisfies IsNotImplemented().
func NotProvisionedf(format string, args ...interface{}) error
NotProvisionedf returns an error which satisfies IsNotProvisioned().
func NotSupportedf(format string, args ...interface{}) error
NotSupportedf returns an error which satisfies IsNotSupported().
func NotValidf(format string, args ...interface{}) error
NotValidf returns an error which satisfies IsNotValid().
func Trace(other error) error
Trace adds the location of the Trace call to the stack. The Cause of the resulting error is the same as the error parameter. If the other error is nil, the result will be nil.
For example:
if err := SomeFunc(); err != nil {
return errors.Trace(err)
}
func Unauthorizedf(format string, args ...interface{}) error
Unauthorizedf returns an error which satisfies IsUnauthorized().
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