Round 4
Signed-off-by: Doug Davis <dug@us.ibm.com>
This commit is contained in:
Doug Davis
parent
b8b16b78f4
commit
56349665b7
13 changed files with 334 additions and 197 deletions
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@ -1,106 +1,29 @@
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package errcode
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import (
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"encoding/json"
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"fmt"
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"net/http"
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"strings"
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"sync"
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)
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// ErrorCoder is the base interface for ErrorCode and Error allowing
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// users of each to just call ErrorCode to get the real ID of each
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type ErrorCoder interface {
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ErrorCode() ErrorCode
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}
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// ErrorCode represents the error type. The errors are serialized via strings
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// and the integer format may change and should *never* be exported.
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type ErrorCode int
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// ErrorDescriptor provides relevant information about a given error code.
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type ErrorDescriptor struct {
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// Code is the error code that this descriptor describes.
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Code ErrorCode
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// Value provides a unique, string key, often captilized with
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// underscores, to identify the error code. This value is used as the
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// keyed value when serializing api errors.
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Value string
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// Message is a short, human readable decription of the error condition
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// included in API responses.
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Message string
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// Description provides a complete account of the errors purpose, suitable
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// for use in documentation.
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Description string
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// HTTPStatusCode provides the http status code that is associated with
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// this error condition.
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HTTPStatusCode int
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// ErrorCode just returns itself
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func (ec ErrorCode) ErrorCode() ErrorCode {
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return ec
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}
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var (
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errorCodeToDescriptors = map[ErrorCode]ErrorDescriptor{}
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idToDescriptors = map[string]ErrorDescriptor{}
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groupToDescriptors = map[string][]ErrorDescriptor{}
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)
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// ErrorCodeUnknown is a generic error that can be used as a last
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// resort if there is no situation-specific error message that can be used
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var ErrorCodeUnknown = Register("registry.api.errcode", ErrorDescriptor{
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Value: "UNKNOWN",
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Message: "unknown error",
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Description: `Generic error returned when the error does not have an
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API classification.`,
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HTTPStatusCode: http.StatusInternalServerError,
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})
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var nextCode = 1000
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var registerLock sync.Mutex
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// Register will make the passed-in error known to the environment and
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// return a new ErrorCode
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func Register(group string, descriptor ErrorDescriptor) ErrorCode {
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registerLock.Lock()
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defer registerLock.Unlock()
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code := ErrorCode(nextCode)
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descriptor.Code = code
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if _, ok := idToDescriptors[descriptor.Value]; ok {
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panic(fmt.Sprintf("ErrorValue %s is already registered", descriptor.Value))
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}
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if _, ok := errorCodeToDescriptors[descriptor.Code]; ok {
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panic(fmt.Sprintf("ErrorCode %d is already registered", descriptor.Code))
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}
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groupToDescriptors[group] = append(groupToDescriptors[group], descriptor)
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errorCodeToDescriptors[code] = descriptor
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idToDescriptors[descriptor.Value] = descriptor
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nextCode++
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return code
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}
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// ParseErrorCode returns the value by the string error code.
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// `ErrorCodeUnknown` will be returned if the error is not known.
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func ParseErrorCode(value string) ErrorCode {
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ed, ok := idToDescriptors[value]
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if ok {
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return ed.Code
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}
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return ErrorCodeUnknown
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}
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// GetGroupNames returns the list of Error group names that are registered
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func GetGroupNames() []string {
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keys := []string{}
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for k := range groupToDescriptors {
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keys = append(keys, k)
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}
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return keys
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}
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// GetErrorCodeGroup returns the named group of error descriptors
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func GetErrorCodeGroup(name string) []ErrorDescriptor {
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return groupToDescriptors[name]
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// Error returns the ID/Value
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func (ec ErrorCode) Error() string {
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return ec.Descriptor().Value
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}
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// Descriptor returns the descriptor for the error code.
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@ -143,12 +66,30 @@ func (ec *ErrorCode) UnmarshalText(text []byte) error {
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return nil
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}
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// WithDetail creates a new Error struct based on the passed-in info and
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// set the Detail property appropriately
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func (ec ErrorCode) WithDetail(detail interface{}) Error {
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if err, ok := detail.(error); ok {
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detail = err.Error()
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}
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return Error{
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Code: ec,
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Detail: detail,
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}
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}
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// Error provides a wrapper around ErrorCode with extra Details provided.
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type Error struct {
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Code ErrorCode `json:"code"`
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Detail interface{} `json:"detail,omitempty"`
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}
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// ErrorCode returns the ID/Value of this Error
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func (e Error) ErrorCode() ErrorCode {
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return e.Code
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}
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// Error returns a human readable representation of the error.
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func (e Error) Error() string {
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return fmt.Sprintf("%s: %s",
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@ -161,30 +102,43 @@ func (e Error) Message() string {
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return e.Code.Message()
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}
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// ErrorDescriptor provides relevant information about a given error code.
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type ErrorDescriptor struct {
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// Code is the error code that this descriptor describes.
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Code ErrorCode
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// Value provides a unique, string key, often captilized with
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// underscores, to identify the error code. This value is used as the
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// keyed value when serializing api errors.
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Value string
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// Message is a short, human readable decription of the error condition
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// included in API responses.
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Message string
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// Description provides a complete account of the errors purpose, suitable
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// for use in documentation.
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Description string
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// HTTPStatusCode provides the http status code that is associated with
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// this error condition.
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HTTPStatusCode int
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}
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// ParseErrorCode returns the value by the string error code.
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// `ErrorCodeUnknown` will be returned if the error is not known.
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func ParseErrorCode(value string) ErrorCode {
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ed, ok := idToDescriptors[value]
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if ok {
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return ed.Code
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}
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return ErrorCodeUnknown
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}
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// Errors provides the envelope for multiple errors and a few sugar methods
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// for use within the application.
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type Errors []Error
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// NewError creates a new Error struct based on the passed-in info
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func NewError(code ErrorCode, details ...interface{}) Error {
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if len(details) > 1 {
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panic("please specify zero or one detail items for this error")
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}
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var detail interface{}
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if len(details) > 0 {
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detail = details[0]
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}
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if err, ok := detail.(error); ok {
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detail = err.Error()
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}
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return Error{
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Code: code,
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Detail: detail,
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}
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}
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type Errors []error
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func (errs Errors) Error() string {
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switch len(errs) {
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@ -205,3 +159,67 @@ func (errs Errors) Error() string {
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func (errs Errors) Len() int {
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return len(errs)
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}
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// jsonError extends Error with 'Message' so that we can include the
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// error text, just in case the receiver of the JSON doesn't have this
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// particular ErrorCode registered
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type jsonError struct {
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Code ErrorCode `json:"code"`
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Message string `json:"message"`
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Detail interface{} `json:"detail,omitempty"`
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}
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// MarshalJSON converts slice of error, ErrorCode or Error into a
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// slice of Error - then serializes
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func (errs Errors) MarshalJSON() ([]byte, error) {
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var tmpErrs []jsonError
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for _, daErr := range errs {
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var err Error
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switch daErr.(type) {
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case ErrorCode:
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err = daErr.(ErrorCode).WithDetail(nil)
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case Error:
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err = daErr.(Error)
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default:
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err = ErrorCodeUnknown.WithDetail(daErr)
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}
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tmpErrs = append(tmpErrs, jsonError{
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Code: err.Code,
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Message: err.Message(),
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Detail: err.Detail,
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})
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}
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return json.Marshal(tmpErrs)
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}
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// UnmarshalJSON deserializes []Error and then converts it into slice of
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// Error or ErrorCode
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func (errs *Errors) UnmarshalJSON(data []byte) error {
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var tmpErrs []jsonError
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if err := json.Unmarshal(data, &tmpErrs); err != nil {
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return err
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}
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var newErrs Errors
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for _, daErr := range tmpErrs {
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if daErr.Detail == nil {
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// Error's w/o details get converted to ErrorCode
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newErrs = append(newErrs, daErr.Code)
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} else {
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// Error's w/ details are untouched
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newErrs = append(newErrs, Error{
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Code: daErr.Code,
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Detail: daErr.Detail,
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})
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}
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}
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*errs = newErrs
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return nil
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}
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