266 lines
6.5 KiB
Go
266 lines
6.5 KiB
Go
package crud
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import (
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"errors"
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"github.com/labstack/echo"
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"reflect"
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"strconv"
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)
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const paramTagName = "param"
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func ParamBinder(i interface{}, c echo.Context) (err error) {
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// Default binder
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db := new(echo.DefaultBinder)
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if err = db.Bind(i, c); err != nil {
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return
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}
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paramNames := c.ParamNames()
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paramValues := c.ParamValues()
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paramVars := make(map[string][]string)
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for in, name := range paramNames {
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paramVars[name] = append(paramVars[name], paramValues[in])
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}
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b := Binder{}
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err = b.bindData(i, paramVars, paramTagName)
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/*
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// Our custom magic starts here
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paramNames := c.ParamNames()
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paramValues := c.ParamValues()
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v := reflect.ValueOf(i)
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t := reflect.TypeOf(i)
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s := reflect.ValueOf(i).Elem()
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for i := 0; i < v.NumField(); i++ {
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field := t.Field(i)
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f := s.Field(i)
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// Check if it has a param tag
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tag := field.Tag.Get(paramTagName)
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if tag != "" {
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// If it has one, range over all url parameters to see if we have a match
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for in, name := range paramNames {
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// Found match
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if tag == name {
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// Put the value of that match in our sruct
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switch field.Type.Name() {
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case "int64": // SetInt only accepts int64, so the struct field can only have int64 of int (no int32/16/int...)
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intParam, err := strconv.ParseInt(paramValues[in], 10, 64)
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f.SetInt(intParam)
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if err != nil {
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return err
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}
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case "string":
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f.SetString(paramValues[in])
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}
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}
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}
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}
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//f.SetString("blub")
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}*/
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return
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}
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// This is kind of ugly, more a "feature proof", copied from the echo source code.
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// Workaround until the pr to implement this nativly in echo is merged.
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type Binder struct{}
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func (b *Binder) bindData(ptr interface{}, data map[string][]string, tag string) error {
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typ := reflect.TypeOf(ptr).Elem()
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val := reflect.ValueOf(ptr).Elem()
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if typ.Kind() != reflect.Struct {
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return errors.New("Binding element must be a struct")
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}
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for i := 0; i < typ.NumField(); i++ {
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typeField := typ.Field(i)
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structField := val.Field(i)
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if !structField.CanSet() {
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continue
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}
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structFieldKind := structField.Kind()
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inputFieldName := typeField.Tag.Get(tag)
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if inputFieldName == "" {
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inputFieldName = typeField.Name
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// If tag is nil, we inspect if the field is a struct.
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if _, ok := bindUnmarshaler(structField); !ok && structFieldKind == reflect.Struct {
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err := b.bindData(structField.Addr().Interface(), data, tag)
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if err != nil {
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return err
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}
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continue
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}
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}
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inputValue, exists := data[inputFieldName]
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if !exists {
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continue
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}
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// Call this first, in case we're dealing with an alias to an array type
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if ok, err := unmarshalField(typeField.Type.Kind(), inputValue[0], structField); ok {
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if err != nil {
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return err
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}
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continue
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}
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numElems := len(inputValue)
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if structFieldKind == reflect.Slice && numElems > 0 {
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sliceOf := structField.Type().Elem().Kind()
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slice := reflect.MakeSlice(structField.Type(), numElems, numElems)
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for j := 0; j < numElems; j++ {
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if err := setWithProperType(sliceOf, inputValue[j], slice.Index(j)); err != nil {
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return err
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}
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}
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val.Field(i).Set(slice)
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} else {
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if err := setWithProperType(typeField.Type.Kind(), inputValue[0], structField); err != nil {
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return err
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}
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}
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}
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return nil
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}
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func setWithProperType(valueKind reflect.Kind, val string, structField reflect.Value) error {
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// But also call it here, in case we're dealing with an array of BindUnmarshalers
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if ok, err := unmarshalField(valueKind, val, structField); ok {
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return err
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}
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switch valueKind {
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case reflect.Int:
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return setIntField(val, 0, structField)
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case reflect.Int8:
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return setIntField(val, 8, structField)
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case reflect.Int16:
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return setIntField(val, 16, structField)
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case reflect.Int32:
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return setIntField(val, 32, structField)
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case reflect.Int64:
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return setIntField(val, 64, structField)
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case reflect.Uint:
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return setUintField(val, 0, structField)
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case reflect.Uint8:
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return setUintField(val, 8, structField)
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case reflect.Uint16:
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return setUintField(val, 16, structField)
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case reflect.Uint32:
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return setUintField(val, 32, structField)
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case reflect.Uint64:
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return setUintField(val, 64, structField)
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case reflect.Bool:
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return setBoolField(val, structField)
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case reflect.Float32:
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return setFloatField(val, 32, structField)
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case reflect.Float64:
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return setFloatField(val, 64, structField)
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case reflect.String:
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structField.SetString(val)
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default:
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return errors.New("unknown type")
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}
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return nil
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}
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func setIntField(value string, bitSize int, field reflect.Value) error {
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if value == "" {
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value = "0"
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}
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intVal, err := strconv.ParseInt(value, 10, bitSize)
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if err == nil {
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field.SetInt(intVal)
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}
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return err
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}
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func setUintField(value string, bitSize int, field reflect.Value) error {
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if value == "" {
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value = "0"
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}
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uintVal, err := strconv.ParseUint(value, 10, bitSize)
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if err == nil {
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field.SetUint(uintVal)
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}
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return err
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}
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func setBoolField(value string, field reflect.Value) error {
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if value == "" {
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value = "false"
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}
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boolVal, err := strconv.ParseBool(value)
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if err == nil {
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field.SetBool(boolVal)
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}
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return err
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}
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func setFloatField(value string, bitSize int, field reflect.Value) error {
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if value == "" {
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value = "0.0"
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}
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floatVal, err := strconv.ParseFloat(value, bitSize)
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if err == nil {
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field.SetFloat(floatVal)
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}
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return err
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}
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type BindUnmarshaler interface {
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// UnmarshalParam decodes and assigns a value from an form or query param.
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UnmarshalParam(param string) error
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}
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// bindUnmarshaler attempts to unmarshal a reflect.Value into a BindUnmarshaler
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func bindUnmarshaler(field reflect.Value) (BindUnmarshaler, bool) {
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ptr := reflect.New(field.Type())
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if ptr.CanInterface() {
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iface := ptr.Interface()
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if unmarshaler, ok := iface.(BindUnmarshaler); ok {
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return unmarshaler, ok
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}
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}
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return nil, false
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}
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func unmarshalField(valueKind reflect.Kind, val string, field reflect.Value) (bool, error) {
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switch valueKind {
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case reflect.Ptr:
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return unmarshalFieldPtr(val, field)
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default:
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return unmarshalFieldNonPtr(val, field)
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}
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}
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func unmarshalFieldNonPtr(value string, field reflect.Value) (bool, error) {
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if unmarshaler, ok := bindUnmarshaler(field); ok {
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err := unmarshaler.UnmarshalParam(value)
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field.Set(reflect.ValueOf(unmarshaler).Elem())
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return true, err
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}
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return false, nil
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}
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func unmarshalFieldPtr(value string, field reflect.Value) (bool, error) {
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if field.IsNil() {
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// Initialize the pointer to a nil value
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field.Set(reflect.New(field.Type().Elem()))
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}
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return unmarshalFieldNonPtr(value, field.Elem())
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}
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