apperr

package module
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 Go to latest Published: Jul 21, 2021 License: Apache-2.0 Imports: 4 Imported by: 4

Documentation

Overview

Package apperr provides a unified application-error generation interface. Errors constructed with apperr can be localized and extended/modified with other options. When finalized they are rendered into a RenderedError object, which can be converted to native error types for various different frameworks like GRPC, Twirp, Plain-HTTP, etc.

Example: 

err := apperr.Unauthenticated("provided password is invalid",
    apperr.Localize("INVALID_PASSWORD"))

In a middleware/interceptor: 

var rendered *apperr.RenderedError
if a, ok := err.(*apperr.AppError); ok {
    rendered, _ = apperr.Render(a, apperr.RenderLocalized(adapter, "en-US"))
} else {
    internal := apperr.Internal("internal error")
    rendered, _ = apperr.Render(internal, apperr.RenderLocalized(adapter, "en-US"))
}
httpStatus, httpBody, _ := httperr.Convert(rendered)

Example Output: 

httpStatus = 401 (Unauthorized)
httpBody =
{
    "message": "provided password is invalid",
    "code": "Unauthenticated",
    "localized": {
        "userMessage": "The entered password isn't correct. Please try again",
        "userMessageShort": "Not authenticated",
        "locale": "en-US"
    }
}

The provided converters are:

  1. GRPC (go get github.com/harwoeck/apperr/grpcerr) grpcStatus, err := grpcerr.Convert(*RenderedError)
  2. HTTP (go get github.com/harwoeck/apperr/httperr) httpStatus, httpBody, err := httperr.Convert(*RenderedError)
  3. Twirp (go get github.com/harwoeck/apperr/twirperr) twirpError := twirperr.Convert(*RenderedError)

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type AppError 

type AppError struct {
	// contains filtered or unexported fields
}

AppError represents a general application error

func Aborted 

func Aborted(msg string, opts ...Option) *AppError

Aborted indicates the operation was aborted, typically due to a concurrency issue like sequencer check failures, transaction aborts, etc.

See litmus test above for deciding between FailedPrecondition, Aborted, and Unavailable.

func AlreadyExists 

func AlreadyExists(msg string, opts ...Option) *AppError

AlreadyExists means an attempt to create an entity failed because one already exists.

func Canceled 

func Canceled(msg string, opts ...Option) *AppError

Canceled indicates the operation was canceled (typically by the caller).

func DataLoss 

func DataLoss(msg string, opts ...Option) *AppError

DataLoss indicates unrecoverable data loss or corruption.

func DeadlineExceeded 

func DeadlineExceeded(msg string, opts ...Option) *AppError

DeadlineExceeded means operation expired before completion. For operations that change the state of the system, this error may be returned even if the operation has completed successfully. For example, a successful response from a server could have been delayed long enough for the deadline to expire.

func FailedPrecondition 

func FailedPrecondition(msg string, opts ...Option) *AppError

FailedPrecondition indicates operation was rejected because the system is not in a state required for the operation's execution. For example, directory to be deleted may be non-empty, an rmdir operation is applied to a non-directory, etc.

A litmus test that may help a service implementor in deciding between FailedPrecondition, Aborted, and Unavailable: 

(a) Use Unavailable if the client can retry just the failing call.
(b) Use Aborted if the client should retry at a higher-level
    (e.g., restarting a read-modify-write sequence).
(c) Use FailedPrecondition if the client should not retry until
    the system state has been explicitly fixed. E.g., if an "rmdir"
    fails because the directory is non-empty, FailedPrecondition
    should be returned since the client should not retry unless
    they have first fixed up the directory by deleting files from it.
(d) Use FailedPrecondition if the client performs conditional
    REST Get/Update/Delete on a resource and the resource on the
    server does not match the condition. E.g., conflicting
    read-modify-write on the same resource.

func Internal 

func Internal(msg string, opts ...Option) *AppError

Internal errors. Means some invariants expected by underlying system has been broken. If you see one of these errors, something is very broken.

func InvalidArgument 

func InvalidArgument(msg string, opts ...Option) *AppError

InvalidArgument indicates client specified an invalid argument. Note that this differs from FailedPrecondition. It indicates arguments that are problematic regardless of the state of the system (e.g., a malformed file name).

func NotFound 

func NotFound(msg string, opts ...Option) *AppError

NotFound means some requested entity (e.g., file or directory) was not found.

func OutOfRange 

func OutOfRange(msg string, opts ...Option) *AppError

OutOfRange means operation was attempted past the valid range. E.g., seeking or reading past end of file.

Unlike InvalidArgument, this error indicates a problem that may be fixed if the system state changes. For example, a 32-bit file system will generate InvalidArgument if asked to read at an offset that is not in the range [0,2^32-1], but it will generate OutOfRange if asked to read from an offset past the current file size.

There is a fair bit of overlap between FailedPrecondition and OutOfRange. We recommend using OutOfRange (the more specific error) when it applies so that callers who are iterating through a space can easily look for an OutOfRange error to detect when they are done.

func PermissionDenied 

func PermissionDenied(msg string, opts ...Option) *AppError

PermissionDenied indicates the caller does not have permission to execute the specified operation. It must not be used for rejections caused by exhausting some resource (use ResourceExhausted instead for those errors). It must not be used if the caller cannot be identified (use Unauthenticated instead for those errors).

func ResourceExhausted 

func ResourceExhausted(msg string, opts ...Option) *AppError

ResourceExhausted indicates some resource has been exhausted, perhaps a per-user quota, or perhaps the entire file system is out of space.

func Unauthenticated 

func Unauthenticated(msg string, opts ...Option) *AppError

Unauthenticated indicates the request does not have valid authentication credentials for the operation.

func Unavailable 

func Unavailable(msg string, opts ...Option) *AppError

Unavailable indicates the service is currently unavailable. This is a most likely a transient condition and may be corrected by retrying with a backoff. Note that it is not always safe to retry non-idempotent operations.

See litmus test above for deciding between FailedPrecondition, Aborted, and Unavailable.

func Unimplemented 

func Unimplemented(msg string, opts ...Option) *AppError

Unimplemented indicates operation is not implemented or not supported/enabled in this service.

func Unknown 

func Unknown(msg string, opts ...Option) *AppError

Unknown error. An example of where this error may be returned is if a Status value received from another address space belongs to an error-space that is not known in this address space. Also errors raised by APIs that do not return enough error information may be converted to this error.

func (*AppError) Error 

func (a *AppError) Error() string

type LocalizationProvider 

type LocalizationProvider interface {
	Localize(msgID string, languages []string) (msg string, tag language.Tag, notFound bool, err error)
	LocalizeFromConfig(cfg interface{}, languages []string) (msg string, tag language.Tag, notFound bool, err error)
}

LocalizationProvider is an interface for localization implementors (libraries). One provided implementation for that uses github.com/nicksnyder/go-i18n as it's backend can be found at adapter/i18n

type Option 

type Option func(*AppError) error

func Localize 

func Localize(msgID string) Option

func LocalizeFromConfig 

func LocalizeFromConfig(cfg interface{}) Option

func LocalizeInLanguage 

func LocalizeInLanguage(msgID, language string) Option

type RenderConfig 

type RenderConfig struct {
	Logger                logger.Logger
	LocalizationProvider  LocalizationProvider
	LocalizationLanguages []string
}

type RenderOption 

type RenderOption func(renderer *RenderConfig) error

func EnableLogging 

func EnableLogging(log logger.Logger) RenderOption

func RenderLocalized 

func RenderLocalized(provider LocalizationProvider, languages ...string) RenderOption

type RenderedError 

type RenderedError struct {
	Code      code.Code
	Message   string
	Localized *RenderedErrorLocalized
}

func Render 

func Render(appError *AppError, opts ...RenderOption) (*RenderedError, error)

type RenderedErrorLocalized 

type RenderedErrorLocalized struct {
	UserMessage      string
	UserMessageShort string
	Locale           language.Tag
}

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