100 lines
3.3 KiB
Go
100 lines
3.3 KiB
Go
/*
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Copyright 2014 Google Inc. All rights reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package errors
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import (
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"fmt"
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"strings"
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)
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// ValidationErrorEnum is a type of validation error.
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type ValidationErrorEnum string
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// These are known errors of validation.
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const (
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Invalid ValidationErrorEnum = "invalid value"
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NotSupported ValidationErrorEnum = "unsupported value"
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Duplicate ValidationErrorEnum = "duplicate value"
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NotFound ValidationErrorEnum = "not found"
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)
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// ValidationError is an implementation of the 'error' interface, which represents an error of validation.
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type ValidationError struct {
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Type ValidationErrorEnum
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Field string
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BadValue interface{}
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}
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func (v ValidationError) Error() string {
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return fmt.Sprintf("%s: %v '%v'", v.Field, v.Type, v.BadValue)
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}
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// NewInvalid returns a ValidationError indicating "invalid value". Use this to
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// report malformed values (e.g. failed regex match) or missing "required" fields.
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func NewInvalid(field string, value interface{}) ValidationError {
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return ValidationError{Invalid, field, value}
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}
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// NewNotSupported returns a ValidationError indicating "unsuported value". Use
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// this to report valid (as per formatting rules) values that can not be handled
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// (e.g. an enumerated string).
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func NewNotSupported(field string, value interface{}) ValidationError {
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return ValidationError{NotSupported, field, value}
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}
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// NewDuplicate returns a ValidationError indicating "duplicate value". Use this
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// to report collisions of values that must be unique (e.g. unique IDs).
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func NewDuplicate(field string, value interface{}) ValidationError {
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return ValidationError{Duplicate, field, value}
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}
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// NewNotFound returns a ValidationError indicating "value not found". Use this
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// to report failure to find a requested value (e.g. looking up an ID).
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func NewNotFound(field string, value interface{}) ValidationError {
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return ValidationError{NotFound, field, value}
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}
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// ErrorList is a collection of errors. This does not implement the error
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// interface to avoid confusion where an empty ErrorList would still be an
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// error (non-nil). To produce a single error instance from an ErrorList, use
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// the ToError() method, which will return nil for an empty ErrorList.
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type ErrorList []error
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// This helper implements the error interface for ErrorList, but must prevents
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// accidental conversion of ErrorList to error.
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type errorListInternal ErrorList
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// Error is part of the error interface.
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func (list errorListInternal) Error() string {
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if len(list) == 0 {
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return ""
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}
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sl := make([]string, len(list))
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for i := range list {
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sl[i] = list[i].Error()
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}
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return strings.Join(sl, "; ")
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}
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// ToError converts an ErrorList into a "normal" error, or nil if the list is empty.
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func (list ErrorList) ToError() error {
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if len(list) == 0 {
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return nil
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}
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return errorListInternal(list)
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}
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