vikunja-api/routes/crud/paramBinder.go

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package crud
import (
"errors"
"github.com/labstack/echo"
"reflect"
"strconv"
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"strings"
)
const paramTagName = "param"
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// ParamBinder binds parameters to a struct.
// Currently a working implementation, waiting to implement this officially into echo.
func ParamBinder(i interface{}, c echo.Context) (err error) {
// Default binder
db := new(echo.DefaultBinder)
if err = db.Bind(i, c); err != nil {
return
}
paramNames := c.ParamNames()
paramValues := c.ParamValues()
paramVars := make(map[string][]string)
for in, name := range paramNames {
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// Hotfix for an echo bug where a param name would show up which dont exist
names := strings.Split(name, ",")
for _, n := range names {
paramVars[n] = append(paramVars[name], paramValues[in])
}
}
b := Binder{}
err = b.bindData(i, paramVars, paramTagName)
/*
// Our custom magic starts here
paramNames := c.ParamNames()
paramValues := c.ParamValues()
v := reflect.ValueOf(i)
t := reflect.TypeOf(i)
s := reflect.ValueOf(i).Elem()
for i := 0; i < v.NumField(); i++ {
field := t.Field(i)
f := s.Field(i)
// Check if it has a param tag
tag := field.Tag.Get(paramTagName)
if tag != "" {
// If it has one, range over all url parameters to see if we have a match
for in, name := range paramNames {
// Found match
if tag == name {
// Put the value of that match in our sruct
switch field.Type.Name() {
case "int64": // SetInt only accepts int64, so the struct field can only have int64 of int (no int32/16/int...)
intParam, err := strconv.ParseInt(paramValues[in], 10, 64)
f.SetInt(intParam)
if err != nil {
return err
}
case "string":
f.SetString(paramValues[in])
}
}
}
}
//f.SetString("blub")
}*/
return
}
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// Binder represents a binder
type Binder struct{}
func (b *Binder) 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 {
err := b.bindData(structField.Addr().Interface(), data, tag)
if err != nil {
return err
}
continue
}
}
inputValue, exists := data[inputFieldName]
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.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 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
}
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// BindUnmarshaler type
type BindUnmarshaler interface {
// UnmarshalParam decodes and assigns a value from an form or query param.
UnmarshalParam(param string) error
}
// 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 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)
}
}
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())
}