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// Copyright 2015 go-swagger maintainers
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package errors
import (
"encoding/json"
"fmt"
"net/http"
"reflect"
"strings"
)
// DefaultHTTPCode is used when the error Code cannot be used as an HTTP code.
var DefaultHTTPCode = http.StatusUnprocessableEntity
// Error represents a error interface all swagger framework errors implement
type Error interface {
error
Code() int32
}
type apiError struct {
code int32
message string
}
func (a *apiError) Error() string {
return a.message
}
func (a *apiError) Code() int32 {
return a.code
}
// MarshalJSON implements the JSON encoding interface
func (a apiError) MarshalJSON() ([]byte, error) {
return json.Marshal(map[string]interface{}{
"code": a.code,
"message": a.message,
})
}
// New creates a new API error with a code and a message
func New(code int32, message string, args ...interface{}) Error {
if len(args) > 0 {
return &apiError{code, fmt.Sprintf(message, args...)}
}
return &apiError{code, message}
}
// NotFound creates a new not found error
func NotFound(message string, args ...interface{}) Error {
if message == "" {
message = "Not found"
}
return New(http.StatusNotFound, fmt.Sprintf(message, args...))
}
// NotImplemented creates a new not implemented error
func NotImplemented(message string) Error {
return New(http.StatusNotImplemented, message)
}
// MethodNotAllowedError represents an error for when the path matches but the method doesn't
type MethodNotAllowedError struct {
code int32
Allowed []string
message string
}
func (m *MethodNotAllowedError) Error() string {
return m.message
}
// Code the error code
func (m *MethodNotAllowedError) Code() int32 {
return m.code
}
// MarshalJSON implements the JSON encoding interface
func (m MethodNotAllowedError) MarshalJSON() ([]byte, error) {
return json.Marshal(map[string]interface{}{
"code": m.code,
"message": m.message,
"allowed": m.Allowed,
})
}
func errorAsJSON(err Error) []byte {
b, _ := json.Marshal(struct {
Code int32 `json:"code"`
Message string `json:"message"`
}{err.Code(), err.Error()})
return b
}
func flattenComposite(errs *CompositeError) *CompositeError {
var res []error
for _, er := range errs.Errors {
switch e := er.(type) {
case *CompositeError:
if len(e.Errors) > 0 {
flat := flattenComposite(e)
if len(flat.Errors) > 0 {
res = append(res, flat.Errors...)
}
}
default:
if e != nil {
res = append(res, e)
}
}
}
return CompositeValidationError(res...)
}
// MethodNotAllowed creates a new method not allowed error
func MethodNotAllowed(requested string, allow []string) Error {
msg := fmt.Sprintf("method %s is not allowed, but [%s] are", requested, strings.Join(allow, ","))
return &MethodNotAllowedError{code: http.StatusMethodNotAllowed, Allowed: allow, message: msg}
}
// ServeError the error handler interface implementation
func ServeError(rw http.ResponseWriter, r *http.Request, err error) {
rw.Header().Set("Content-Type", "application/json")
switch e := err.(type) {
case *CompositeError:
er := flattenComposite(e)
// strips composite errors to first element only
if len(er.Errors) > 0 {
ServeError(rw, r, er.Errors[0])
} else {
// guard against empty CompositeError (invalid construct)
ServeError(rw, r, nil)
}
case *MethodNotAllowedError:
rw.Header().Add("Allow", strings.Join(err.(*MethodNotAllowedError).Allowed, ","))
rw.WriteHeader(asHTTPCode(int(e.Code())))
if r == nil || r.Method != http.MethodHead {
_, _ = rw.Write(errorAsJSON(e))
}
case Error:
value := reflect.ValueOf(e)
if value.Kind() == reflect.Ptr && value.IsNil() {
rw.WriteHeader(http.StatusInternalServerError)
_, _ = rw.Write(errorAsJSON(New(http.StatusInternalServerError, "Unknown error")))
return
}
rw.WriteHeader(asHTTPCode(int(e.Code())))
if r == nil || r.Method != http.MethodHead {
_, _ = rw.Write(errorAsJSON(e))
}
case nil:
rw.WriteHeader(http.StatusInternalServerError)
_, _ = rw.Write(errorAsJSON(New(http.StatusInternalServerError, "Unknown error")))
default:
rw.WriteHeader(http.StatusInternalServerError)
if r == nil || r.Method != http.MethodHead {
_, _ = rw.Write(errorAsJSON(New(http.StatusInternalServerError, err.Error())))
}
}
}
func asHTTPCode(input int) int {
if input >= 600 {
return DefaultHTTPCode
}
return input
}
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