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package echo
import (
"encoding/json"
"encoding/xml"
"errors"
"fmt"
"net/http"
"reflect"
"strconv"
"strings"
)
type (
// Binder is the interface that wraps the Bind method.
Binder interface {
Bind(i interface{}, c Context) error
}
// DefaultBinder is the default implementation of the Binder interface.
DefaultBinder struct{}
// BindUnmarshaler is the interface used to wrap the UnmarshalParam method.
BindUnmarshaler interface {
// UnmarshalParam decodes and assigns a value from an form or query param.
UnmarshalParam(param string) error
}
)
// Bind implements the `Binder#Bind` function.
func (b *DefaultBinder) Bind(i interface{}, c Context) (err error) {
req := c.Request()
if req.ContentLength == 0 {
if req.Method == http.MethodGet || req.Method == http.MethodDelete {
if err = b.bindData(i, c.QueryParams(), "query"); err != nil {
return NewHTTPError(http.StatusBadRequest, err.Error()).SetInternal(err)
}
return
}
return NewHTTPError(http.StatusBadRequest, "Request body can't be empty")
}
ctype := req.Header.Get(HeaderContentType)
switch {
case strings.HasPrefix(ctype, MIMEApplicationJSON):
if err = json.NewDecoder(req.Body).Decode(i); err != nil {
if ute, ok := err.(*json.UnmarshalTypeError); ok {
return NewHTTPError(http.StatusBadRequest, fmt.Sprintf("Unmarshal type error: expected=%v, got=%v, field=%v, offset=%v", ute.Type, ute.Value, ute.Field, ute.Offset)).SetInternal(err)
} else if se, ok := err.(*json.SyntaxError); ok {
return NewHTTPError(http.StatusBadRequest, fmt.Sprintf("Syntax error: offset=%v, error=%v", se.Offset, se.Error())).SetInternal(err)
}
return NewHTTPError(http.StatusBadRequest, err.Error()).SetInternal(err)
}
case strings.HasPrefix(ctype, MIMEApplicationXML), strings.HasPrefix(ctype, MIMETextXML):
if err = xml.NewDecoder(req.Body).Decode(i); err != nil {
if ute, ok := err.(*xml.UnsupportedTypeError); ok {
return NewHTTPError(http.StatusBadRequest, fmt.Sprintf("Unsupported type error: type=%v, error=%v", ute.Type, ute.Error())).SetInternal(err)
} else if se, ok := err.(*xml.SyntaxError); ok {
return NewHTTPError(http.StatusBadRequest, fmt.Sprintf("Syntax error: line=%v, error=%v", se.Line, se.Error())).SetInternal(err)
}
return NewHTTPError(http.StatusBadRequest, err.Error()).SetInternal(err)
}
case strings.HasPrefix(ctype, MIMEApplicationForm), strings.HasPrefix(ctype, MIMEMultipartForm):
params, err := c.FormParams()
if err != nil {
return NewHTTPError(http.StatusBadRequest, err.Error()).SetInternal(err)
}
if err = b.bindData(i, params, "form"); err != nil {
return NewHTTPError(http.StatusBadRequest, err.Error()).SetInternal(err)
}
default:
return ErrUnsupportedMediaType
}
return
}
func (b *DefaultBinder) bindData(ptr interface{}, data map[string][]string, tag string) error {
typ := reflect.TypeOf(ptr).Elem()
val := reflect.ValueOf(ptr).Elem()
if typ.Kind() != reflect.Struct {
return errors.New("binding element must be a struct")
}
for i := 0; i < typ.NumField(); i++ {
typeField := typ.Field(i)
structField := val.Field(i)
if !structField.CanSet() {
continue
}
structFieldKind := structField.Kind()
inputFieldName := typeField.Tag.Get(tag)
if inputFieldName == "" {
inputFieldName = typeField.Name
// If tag is nil, we inspect if the field is a struct.
if _, ok := bindUnmarshaler(structField); !ok && structFieldKind == reflect.Struct {
if err := b.bindData(structField.Addr().Interface(), data, tag); err != nil {
return err
}
continue
}
}
inputValue, exists := data[inputFieldName]
if !exists {
// Go json.Unmarshal supports case insensitive binding. However the
// url params are bound case sensitive which is inconsistent. To
// fix this we must check all of the map values in a
// case-insensitive search.
inputFieldName = strings.ToLower(inputFieldName)
for k, v := range data {
if strings.ToLower(k) == inputFieldName {
inputValue = v
exists = true
break
}
}
}
if !exists {
continue
}
// Call this first, in case we're dealing with an alias to an array type
if ok, err := unmarshalField(typeField.Type.Kind(), inputValue[0], structField); ok {
if err != nil {
return err
}
continue
}
numElems := len(inputValue)
if structFieldKind == reflect.Slice && numElems > 0 {
sliceOf := structField.Type().Elem().Kind()
slice := reflect.MakeSlice(structField.Type(), numElems, numElems)
for j := 0; j < numElems; j++ {
if err := setWithProperType(sliceOf, inputValue[j], slice.Index(j)); err != nil {
return err
}
}
val.Field(i).Set(slice)
} else if err := setWithProperType(typeField.Type.Kind(), inputValue[0], structField); err != nil {
return err
}
}
return nil
}
func setWithProperType(valueKind reflect.Kind, val string, structField reflect.Value) error {
// But also call it here, in case we're dealing with an array of BindUnmarshalers
if ok, err := unmarshalField(valueKind, val, structField); ok {
return err
}
switch valueKind {
case reflect.Ptr:
return setWithProperType(structField.Elem().Kind(), val, structField.Elem())
case reflect.Int:
return setIntField(val, 0, structField)
case reflect.Int8:
return setIntField(val, 8, structField)
case reflect.Int16:
return setIntField(val, 16, structField)
case reflect.Int32:
return setIntField(val, 32, structField)
case reflect.Int64:
return setIntField(val, 64, structField)
case reflect.Uint:
return setUintField(val, 0, structField)
case reflect.Uint8:
return setUintField(val, 8, structField)
case reflect.Uint16:
return setUintField(val, 16, structField)
case reflect.Uint32:
return setUintField(val, 32, structField)
case reflect.Uint64:
return setUintField(val, 64, structField)
case reflect.Bool:
return setBoolField(val, structField)
case reflect.Float32:
return setFloatField(val, 32, structField)
case reflect.Float64:
return setFloatField(val, 64, structField)
case reflect.String:
structField.SetString(val)
default:
return errors.New("unknown type")
}
return nil
}
func unmarshalField(valueKind reflect.Kind, val string, field reflect.Value) (bool, error) {
switch valueKind {
case reflect.Ptr:
return unmarshalFieldPtr(val, field)
default:
return unmarshalFieldNonPtr(val, field)
}
}
// bindUnmarshaler attempts to unmarshal a reflect.Value into a BindUnmarshaler
func bindUnmarshaler(field reflect.Value) (BindUnmarshaler, bool) {
ptr := reflect.New(field.Type())
if ptr.CanInterface() {
iface := ptr.Interface()
if unmarshaler, ok := iface.(BindUnmarshaler); ok {
return unmarshaler, ok
}
}
return nil, false
}
func unmarshalFieldNonPtr(value string, field reflect.Value) (bool, error) {
if unmarshaler, ok := bindUnmarshaler(field); ok {
err := unmarshaler.UnmarshalParam(value)
field.Set(reflect.ValueOf(unmarshaler).Elem())
return true, err
}
return false, nil
}
func unmarshalFieldPtr(value string, field reflect.Value) (bool, error) {
if field.IsNil() {
// Initialize the pointer to a nil value
field.Set(reflect.New(field.Type().Elem()))
}
return unmarshalFieldNonPtr(value, field.Elem())
}
func setIntField(value string, bitSize int, field reflect.Value) error {
if value == "" {
value = "0"
}
intVal, err := strconv.ParseInt(value, 10, bitSize)
if err == nil {
field.SetInt(intVal)
}
return err
}
func setUintField(value string, bitSize int, field reflect.Value) error {
if value == "" {
value = "0"
}
uintVal, err := strconv.ParseUint(value, 10, bitSize)
if err == nil {
field.SetUint(uintVal)
}
return err
}
func setBoolField(value string, field reflect.Value) error {
if value == "" {
value = "false"
}
boolVal, err := strconv.ParseBool(value)
if err == nil {
field.SetBool(boolVal)
}
return err
}
func setFloatField(value string, bitSize int, field reflect.Value) error {
if value == "" {
value = "0.0"
}
floatVal, err := strconv.ParseFloat(value, bitSize)
if err == nil {
field.SetFloat(floatVal)
}
return err
}