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// SPDX-License-Identifier: MIT
// SPDX-FileCopyrightText: © 2015 LabStack LLC and Echo contributors
package echo
import (
"encoding"
"encoding/xml"
"errors"
"fmt"
"mime/multipart"
"net/http"
"reflect"
"strconv"
"strings"
"sync"
"time"
)
// Binder is the interface that wraps the Bind method.
type Binder interface {
Bind(c *Context, target any) error
}
// DefaultBinder is the default implementation of the Binder interface.
// For path, query, header, and form binding, time.Time and *time.Time fields (not slices)
// may use a format tag: "date-time" uses the standard RFC3339 decoding, "date-time-local"
// accepts "2006-01-02T15:04:05" with optional fractional seconds, "date" accepts
// "2006-01-02", and other values specify Go time layouts. "date", "date-time-local", and
// layouts without a timezone give UTC times. JSON and XML decoding do not use this tag.
// HTML datetime-local inputs omit seconds by default, so bind them with a Go layout
// such as "2006-01-02T15:04" instead of "date-time-local".
type DefaultBinder struct{}
// BindUnmarshaler is the interface used to wrap the UnmarshalParam method.
// Types that don't implement this, but do implement encoding.TextUnmarshaler
// will use that interface instead.
type BindUnmarshaler interface {
// UnmarshalParam decodes and assigns a value from an form or query param.
UnmarshalParam(param string) error
}
// bindMultipleUnmarshaler is used by binder to unmarshal multiple values from request at once to
// type implementing this interface. For example request could have multiple query fields `?a=1&a=2&b=test` in that case
// for `a` following slice `["1", "2"] will be passed to unmarshaller.
type bindMultipleUnmarshaler interface {
UnmarshalParams(params []string) error
}
// BindPathValues binds path parameter values to bindable object
func BindPathValues(c *Context, target any) error {
params := map[string][]string{}
for _, param := range c.PathValues() {
params[param.Name] = []string{param.Value}
}
if err := bindData(target, params, "param", nil); err != nil {
return ErrBadRequest.Wrap(err)
}
return nil
}
// BindQueryParams binds query params to bindable object
func BindQueryParams(c *Context, target any) error {
if err := bindData(target, c.QueryParams(), "query", nil); err != nil {
return ErrBadRequest.Wrap(err)
}
return nil
}
// BindBody binds request body contents to bindable object
// NB: then binding forms take note that this implementation uses standard library form parsing
// which parses form data from BOTH URL and BODY if content type is not MIMEMultipartForm
// See non-MIMEMultipartForm: https://golang.org/pkg/net/http/#Request.ParseForm
// See MIMEMultipartForm: https://golang.org/pkg/net/http/#Request.ParseMultipartForm
func BindBody(c *Context, target any) (err error) {
req := c.Request()
if req.ContentLength == 0 {
return
}
// mediatype is found like `mime.ParseMediaType()` does it
base, _, _ := strings.Cut(req.Header.Get(HeaderContentType), ";")
mediatype := strings.TrimSpace(base)
switch mediatype {
case MIMEApplicationJSON:
if err = c.Echo().JSONSerializer.Deserialize(c, target); err != nil {
return wrapBindBodyError(err)
}
case MIMEApplicationXML, MIMETextXML:
if err = xml.NewDecoder(req.Body).Decode(target); err != nil {
return wrapBindBodyError(err)
}
case MIMEApplicationForm:
params, err := c.FormValues()
if err != nil {
return wrapBindBodyError(err)
}
if err = bindData(target, params, "form", nil); err != nil {
return ErrBadRequest.Wrap(err)
}
case MIMEMultipartForm:
params, err := c.MultipartForm()
if err != nil {
return wrapBindBodyError(err)
}
if err = bindData(target, params.Value, "form", params.File); err != nil {
return ErrBadRequest.Wrap(err)
}
default:
return &HTTPError{Code: http.StatusUnsupportedMediaType}
}
return nil
}
func wrapBindBodyError(err error) error {
if StatusCode(err) != 0 {
return err
}
return ErrBadRequest.Wrap(err)
}
// BindHeaders binds HTTP headers to a bindable object
func BindHeaders(c *Context, target any) error {
if err := bindData(target, c.Request().Header, "header", nil); err != nil {
return ErrBadRequest.Wrap(err)
}
return nil
}
// Bind implements the `Binder#Bind` function.
// Binding is done in following order: 1) path params; 2) query params; 3) request body. Each step COULD override previous
// step bound values. For single source binding use their own methods BindBody, BindQueryParams, BindPathValues.
func (b *DefaultBinder) Bind(c *Context, target any) error {
if err := BindPathValues(c, target); err != nil {
return err
}
// Only bind query parameters for GET/DELETE/HEAD/QUERY to avoid unexpected behavior with destination struct binding from body.
// For example a request URL `&id=1&lang=en` with body `{"id":100,"lang":"de"}` would lead to precedence issues.
// The HTTP method check restores pre-v4.1.11 behavior to avoid these problems (see issue #1670)
method := c.Request().Method
if method == http.MethodGet || method == http.MethodDelete || method == http.MethodHead || method == QUERY {
if err := BindQueryParams(c, target); err != nil {
return err
}
}
return BindBody(c, target)
}
// bindFieldMeta is the cached, type-level reflection metadata for a single struct field. Reading struct
// tags (reflect.StructTag.Get) parses the tag string on every call, so for binding-heavy endpoints we
// compute it once per struct type and reuse it across requests (see bindStructMeta). Only type-level data
// is cached here; per-request, per-instance reflect.Value operations still happen in bindData.
type bindFieldMeta struct {
index int // field index within the struct
// fieldKind is the DECLARED field kind (typeField.Type.Kind()), used only for unmarshal dispatch.
// It is intentionally not the post-anonymous-pointer-deref live kind; bindData computes that
// separately as structFieldKind where needed.
fieldKind reflect.Kind
anonymous bool // reflect.StructField.Anonymous
formatTag string // value of the `format` struct tag
// binding-source tag values. bindData is only ever called with one of these four tags (see the
// callers BindPathValues/BindQueryParams/BindBody/BindHeaders). Keep these fields, the four
// f.Tag.Get(...) lines in bindMetaFor, and the tagName switch in sync if a source is ever added.
param, query, form, header string
}
// tagName returns the field's tag value for the given binding source tag.
// Keep in sync with the tag fields above and the f.Tag.Get calls in bindMetaFor.
func (m *bindFieldMeta) tagName(tag string) string {
switch tag {
case "param":
return m.param
case "query":
return m.query
case "form":
return m.form
case "header":
return m.header
default:
return ""
}
}
// bindStructMeta is the cached field metadata for a whole struct type, in declaration order.
type bindStructMeta struct {
fields []bindFieldMeta
}
// bindStructCache memoizes bindStructMeta keyed by struct reflect.Type. Concurrent double-computation is
// harmless because the result is deterministic and idempotent.
var bindStructCache sync.Map // map[reflect.Type]*bindStructMeta
func bindMetaFor(typ reflect.Type) *bindStructMeta {
if cached, ok := bindStructCache.Load(typ); ok {
return cached.(*bindStructMeta)
}
n := typ.NumField()
meta := &bindStructMeta{fields: make([]bindFieldMeta, n)}
for i := range n {
f := typ.Field(i)
meta.fields[i] = bindFieldMeta{
index: i,
anonymous: f.Anonymous,
fieldKind: f.Type.Kind(),
formatTag: f.Tag.Get("format"),
param: f.Tag.Get("param"),
query: f.Tag.Get("query"),
form: f.Tag.Get("form"),
header: f.Tag.Get("header"),
}
}
bindStructCache.Store(typ, meta)
return meta
}
// bindData will bind data ONLY fields in destination struct that have EXPLICIT tag
func bindData(destination any, data map[string][]string, tag string, dataFiles map[string][]*multipart.FileHeader) error {
if destination == nil || (len(data) == 0 && len(dataFiles) == 0) {
return nil
}
hasFiles := len(dataFiles) > 0
typ := reflect.TypeOf(destination).Elem()
val := reflect.ValueOf(destination).Elem()
// Support binding to limited Map destinations:
// - map[string][]string,
// - map[string]string <-- (binds first value from data slice)
// - map[string]any
// You are better off binding to struct but there are user who want this map feature. Source of data for these cases are:
// params,query,header,form as these sources produce string values, most of the time slice of strings, actually.
if typ.Kind() == reflect.Map && typ.Key().Kind() == reflect.String {
k := typ.Elem().Kind()
isElemInterface := k == reflect.Interface
isElemString := k == reflect.String
isElemSliceOfStrings := k == reflect.Slice && typ.Elem().Elem().Kind() == reflect.String
if !isElemSliceOfStrings && !isElemString && !isElemInterface {
return nil
}
if val.IsNil() {
val.Set(reflect.MakeMap(typ))
}
for k, v := range data {
if isElemString {
val.SetMapIndex(reflect.ValueOf(k), reflect.ValueOf(v[0]))
} else if isElemInterface {
// To maintain backward compatibility, we always bind to the first string value
// and not the slice of strings when dealing with map[string]any{}
val.SetMapIndex(reflect.ValueOf(k), reflect.ValueOf(v[0]))
} else {
val.SetMapIndex(reflect.ValueOf(k), reflect.ValueOf(v))
}
}
return nil
}
// !struct
if typ.Kind() != reflect.Struct {
if tag == "param" || tag == "query" || tag == "header" {
// incompatible type, data is probably to be found in the body
return nil
}
return errors.New("binding element must be a struct")
}
meta := bindMetaFor(typ)
for fi := range meta.fields { // iterate over all destination fields
fm := &meta.fields[fi]
structField := val.Field(fm.index)
if fm.anonymous {
if structField.Kind() == reflect.Pointer {
structField = structField.Elem()
}
}
if !structField.CanSet() {
continue
}
structFieldKind := structField.Kind()
inputFieldName := fm.tagName(tag)
if fm.anonymous && structFieldKind == reflect.Struct && inputFieldName != "" {
// if anonymous struct with query/param/form tags, report an error
return errors.New("query/param/form tags are not allowed with anonymous struct field")
}
if inputFieldName == "" {
// If tag is nil, we inspect if the field is a not BindUnmarshaler struct and try to bind data into it (might contain fields with tags).
// structs that implement BindUnmarshaler are bound only when they have explicit tag
if _, ok := structField.Addr().Interface().(BindUnmarshaler); !ok && structFieldKind == reflect.Struct {
if err := bindData(structField.Addr().Interface(), data, tag, dataFiles); err != nil {
return err
}
}
// does not have explicit tag and is not an ordinary struct - so move to next field
continue
}
if hasFiles {
if ok, err := isFieldMultipartFile(structField.Type()); err != nil {
return err
} else if ok {
if ok := setMultipartFileHeaderTypes(structField, inputFieldName, dataFiles); ok {
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.
for k, v := range data {
if strings.EqualFold(k, inputFieldName) {
inputValue = v
exists = true
break
}
}
}
if !exists {
continue
}
// NOTE: algorithm here is not particularly sophisticated. It probably does not work with absurd types like `**[]*int`
// but it is smart enough to handle niche cases like `*int`,`*[]string`,`[]*int` .
// try unmarshalling first, in case we're dealing with an alias to an array type
if ok, err := unmarshalInputsToField(fm.fieldKind, inputValue, structField); ok {
if err != nil {
return fmt.Errorf("%s: %w", inputFieldName, err)
}
continue
}
if ok, err := unmarshalInputToField(fm.fieldKind, inputValue[0], structField, fm.formatTag); ok {
if err != nil {
return fmt.Errorf("%s: %w", inputFieldName, err)
}
continue
}
// we could be dealing with pointer to slice `*[]string` so dereference it. There are weird OpenAPI generators
// that could create struct fields like that.
if structFieldKind == reflect.Pointer {
structFieldKind = structField.Elem().Kind()
structField = structField.Elem()
}
if structFieldKind == reflect.Slice {
sliceOf := structField.Type().Elem().Kind()
numElems := len(inputValue)
slice := reflect.MakeSlice(structField.Type(), numElems, numElems)
for j := range numElems {
if err := setWithProperType(sliceOf, inputValue[j], slice.Index(j)); err != nil {
return fmt.Errorf("%s: %w", inputFieldName, err)
}
}
structField.Set(slice)
continue
}
if err := setWithProperType(structFieldKind, inputValue[0], structField); err != nil {
return fmt.Errorf("%s: %w", inputFieldName, 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
// Note: format tag not available in this context, so empty string is passed
if ok, err := unmarshalInputToField(valueKind, val, structField, ""); ok {
return err
}
switch valueKind {
case reflect.Pointer:
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 unmarshalInputsToField(valueKind reflect.Kind, values []string, field reflect.Value) (bool, error) {
if valueKind == reflect.Pointer {
if field.IsNil() {
field.Set(reflect.New(field.Type().Elem()))
}
field = field.Elem()
}
fieldIValue := field.Addr().Interface()
unmarshaler, ok := fieldIValue.(bindMultipleUnmarshaler)
if !ok {
return false, nil
}
return true, unmarshaler.UnmarshalParams(values)
}
func unmarshalInputToField(valueKind reflect.Kind, val string, field reflect.Value, formatTag string) (bool, error) {
if valueKind == reflect.Pointer {
if field.IsNil() {
field.Set(reflect.New(field.Type().Elem()))
}
field = field.Elem()
}
fieldIValue := field.Addr().Interface()
// date-time uses the same TextUnmarshaler as an untagged time.Time.
if formatTag != "" && formatTag != "date-time" {
if _, isTime := fieldIValue.(*time.Time); isTime {
// OpenAPI dates and local date-times have no timezone. time.Parse assigns UTC,
// as it does for custom layouts without timezone information.
layout := formatTag
switch formatTag {
case "date":
layout = "2006-01-02"
case "date-time-local":
layout = "2006-01-02T15:04:05"
}
t, err := time.Parse(layout, val)
if err != nil {
return true, err
}
field.Set(reflect.ValueOf(t))
return true, nil
}
}
switch unmarshaler := fieldIValue.(type) {
case BindUnmarshaler:
return true, unmarshaler.UnmarshalParam(val)
case encoding.TextUnmarshaler:
return true, unmarshaler.UnmarshalText([]byte(val))
}
return false, nil
}
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
}
var (
// NOT supported by bind as you can NOT check easily empty struct being actual file or not
multipartFileHeaderType = reflect.TypeFor[multipart.FileHeader]()
// supported by bind as you can check by nil value if file existed or not
multipartFileHeaderPointerType = reflect.TypeFor[*multipart.FileHeader]()
multipartFileHeaderSliceType = reflect.TypeFor[[]multipart.FileHeader]()
multipartFileHeaderPointerSliceType = reflect.TypeFor[[]*multipart.FileHeader]()
)
func isFieldMultipartFile(field reflect.Type) (bool, error) {
switch field {
case multipartFileHeaderPointerType,
multipartFileHeaderSliceType,
multipartFileHeaderPointerSliceType:
return true, nil
case multipartFileHeaderType:
return true, errors.New("binding to multipart.FileHeader struct is not supported, use pointer to struct")
default:
return false, nil
}
}
func setMultipartFileHeaderTypes(structField reflect.Value, inputFieldName string, files map[string][]*multipart.FileHeader) bool {
fileHeaders := files[inputFieldName]
if len(fileHeaders) == 0 {
return false
}
result := true
switch structField.Type() {
case multipartFileHeaderPointerSliceType:
structField.Set(reflect.ValueOf(fileHeaders))
case multipartFileHeaderSliceType:
headers := make([]multipart.FileHeader, len(fileHeaders))
for i, fileHeader := range fileHeaders {
headers[i] = *fileHeader
}
structField.Set(reflect.ValueOf(headers))
case multipartFileHeaderPointerType:
structField.Set(reflect.ValueOf(fileHeaders[0]))
default:
result = false
}
return result
}