/
decode.go
145 lines (114 loc) · 3.18 KB
/
decode.go
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package faunadb
import (
"fmt"
"reflect"
)
// A DecodeError describes an error when decoding a Fauna Value to a native Golang type
type DecodeError struct {
path path
err error
}
func (d DecodeError) Error() string {
path := d.path
err := d.err
for {
if decodeErr, ok := err.(DecodeError); ok {
path = path.subPath(decodeErr.path)
err = decodeErr.err
} else {
break
}
}
return fmt.Sprintf("Error while decoding fauna value at: %s. %s", path, err)
}
type valueDecoder struct {
target reflect.Value
targetType reflect.Type
}
func newValueDecoder(source interface{}) *valueDecoder {
target, targetType := indirectValue(source)
return &valueDecoder{
target: target,
targetType: targetType,
}
}
func (c *valueDecoder) assign(value interface{}) error {
source, sourceType := indirectValue(value)
if sourceType.AssignableTo(c.targetType) {
c.target.Set(source)
return nil
}
if sourceType.ConvertibleTo(c.targetType) {
c.target.Set(source.Convert(c.targetType))
return nil
}
return DecodeError{
err: fmt.Errorf("Can not assign value of type \"%s\" to a value of type \"%s\"", sourceType, c.targetType),
}
}
func (c *valueDecoder) decodeArray(arr ArrayV) error {
if err := c.assign(arr); err == nil {
return nil
}
if c.target.Kind() != reflect.Slice {
return DecodeError{err: fmt.Errorf("Can not decode array into a value of type \"%s\"", c.targetType)}
}
return c.makeNewSlice(arr)
}
func (c *valueDecoder) makeNewSlice(arr []Value) error {
newArray := reflect.MakeSlice(c.targetType, len(arr), len(arr))
for index, value := range arr {
if err := value.Get(newArray.Index(index)); err != nil {
return DecodeError{path: pathFromIndexes(index), err: err}
}
}
return c.assign(newArray)
}
func (c *valueDecoder) decodeMap(obj ObjectV) error {
if err := c.assign(obj); err == nil {
return nil
}
switch c.target.Kind() {
case reflect.Map:
return c.makeNewMap(obj)
case reflect.Struct:
return c.fillStructFields(obj)
default:
return DecodeError{err: fmt.Errorf("Can not decode map into a value of type \"%s\"", c.targetType)}
}
}
func (c *valueDecoder) makeNewMap(obj map[string]Value) error {
newMap := reflect.MakeMap(c.targetType)
elemType := c.targetType.Elem()
for key, value := range obj {
newElem := reflect.New(elemType).Elem()
if err := value.Get(newElem); err != nil {
return DecodeError{path: pathFromKeys(key), err: err}
}
newMap.SetMapIndex(reflect.ValueOf(key), newElem)
}
return c.assign(newMap)
}
func (c *valueDecoder) fillStructFields(obj map[string]Value) (err error) {
newStruct := reflect.New(c.targetType).Elem()
aStructType := newStruct.Type()
//need to get all StructFields and unpack json values into the fields to check if they are empty - use allStructFields rather than
for key, field := range allStructFields(newStruct) {
f, _ := aStructType.FieldByName(key)
if !field.CanInterface() {
continue
}
fieldName, ignored, _, _ := parseTag(f) //need to parse tags
value, found := obj[fieldName]
if !found {
continue
}
if ignored {
continue
}
if err = value.Get(field); err != nil {
return DecodeError{path: pathFromKeys(key), err: err}
}
}
return c.assign(newStruct)
}