253 lines
6.2 KiB
Go
253 lines
6.2 KiB
Go
package errcode
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import (
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"encoding/json"
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"fmt"
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"strings"
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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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// 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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// 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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func (ec ErrorCode) Descriptor() ErrorDescriptor {
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d, ok := errorCodeToDescriptors[ec]
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if !ok {
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return ErrorCodeUnknown.Descriptor()
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}
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return d
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}
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// String returns the canonical identifier for this error code.
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func (ec ErrorCode) String() string {
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return ec.Descriptor().Value
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}
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// Message returned the human-readable error message for this error code.
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func (ec ErrorCode) Message() string {
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return ec.Descriptor().Message
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}
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// MarshalText encodes the receiver into UTF-8-encoded text and returns the
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// result.
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func (ec ErrorCode) MarshalText() (text []byte, err error) {
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return []byte(ec.String()), nil
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}
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// UnmarshalText decodes the form generated by MarshalText.
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func (ec *ErrorCode) UnmarshalText(text []byte) error {
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desc, ok := idToDescriptors[string(text)]
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if !ok {
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desc = ErrorCodeUnknown.Descriptor()
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}
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*ec = desc.Code
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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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return Error{
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Code: ec,
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Message: ec.Message(),
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}.WithDetail(detail)
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}
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// WithArgs creates a new Error struct and sets the Args slice
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func (ec ErrorCode) WithArgs(args ...interface{}) Error {
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return Error{
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Code: ec,
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Message: ec.Message(),
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}.WithArgs(args...)
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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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Message string `json:"message"`
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Detail interface{} `json:"detail,omitempty"`
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// TODO(duglin): See if we need an "args" property so we can do the
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// variable substitution right before showing the message to the user
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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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strings.ToLower(strings.Replace(e.Code.String(), "_", " ", -1)),
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e.Code.Message())
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}
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// WithDetail will return a new Error, based on the current one, but with
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// some Detail info added
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func (e Error) WithDetail(detail interface{}) Error {
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return Error{
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Code: e.Code,
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Message: e.Message,
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Detail: detail,
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}
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}
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// WithArgs uses the passed-in list of interface{} as the substitution
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// variables in the Error's Message string, but returns a new Error
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func (e Error) WithArgs(args ...interface{}) Error {
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return Error{
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Code: e.Code,
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Message: fmt.Sprintf(e.Code.Message(), args...),
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Detail: e.Detail,
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}
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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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func (errs Errors) Error() string {
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switch len(errs) {
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case 0:
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return "<nil>"
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case 1:
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return errs[0].Error()
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default:
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msg := "errors:\n"
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for _, err := range errs {
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msg += err.Error() + "\n"
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}
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return msg
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}
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}
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// Len returns the current number of errors.
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func (errs Errors) Len() int {
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return len(errs)
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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 struct {
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Errors []Error `json:"errors,omitempty"`
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}
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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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// If the Error struct was setup and they forgot to set the
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// Message field (meaning its "") then grab it from the ErrCode
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msg := err.Message
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if msg == "" {
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msg = err.Code.Message()
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}
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tmpErrs.Errors = append(tmpErrs.Errors, Error{
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Code: err.Code,
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Message: msg,
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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 struct {
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Errors []Error
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}
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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.Errors {
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// If Message is empty or exactly matches the Code's message string
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// then just use the Code, no need for a full Error struct
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if daErr.Detail == nil && (daErr.Message == "" || daErr.Message == daErr.Code.Message()) {
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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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Message: daErr.Message,
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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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