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// Copyright 2014 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package datastore
import (
"fmt"
"reflect"
"strings"
"time"
"cloud.google.com/go/internal/fields"
pb "google.golang.org/genproto/googleapis/datastore/v1"
)
var (
typeOfByteSlice = reflect.TypeOf([]byte(nil))
typeOfTime = reflect.TypeOf(time.Time{})
typeOfGeoPoint = reflect.TypeOf(GeoPoint{})
typeOfKeyPtr = reflect.TypeOf(&Key{})
)
// typeMismatchReason returns a string explaining why the property p could not
// be stored in an entity field of type v.Type().
func typeMismatchReason(p Property, v reflect.Value) string {
entityType := "empty"
switch p.Value.(type) {
case int64:
entityType = "int"
case bool:
entityType = "bool"
case string:
entityType = "string"
case float64:
entityType = "float"
case *Key:
entityType = "*datastore.Key"
case *Entity:
entityType = "*datastore.Entity"
case GeoPoint:
entityType = "GeoPoint"
case time.Time:
entityType = "time.Time"
case []byte:
entityType = "[]byte"
}
return fmt.Sprintf("type mismatch: %s versus %v", entityType, v.Type())
}
func overflowReason(x interface{}, v reflect.Value) string {
return fmt.Sprintf("value %v overflows struct field of type %v", x, v.Type())
}
type propertyLoader struct {
// m holds the number of times a substruct field like "Foo.Bar.Baz" has
// been seen so far. The map is constructed lazily.
m map[string]int
}
func (l *propertyLoader) load(codec fields.List, structValue reflect.Value, p Property, prev map[string]struct{}) string {
sl, ok := p.Value.([]interface{})
if !ok {
return l.loadOneElement(codec, structValue, p, prev)
}
for _, val := range sl {
p.Value = val
if errStr := l.loadOneElement(codec, structValue, p, prev); errStr != "" {
return errStr
}
}
return ""
}
// loadOneElement loads the value of Property p into structValue based on the provided
// codec. codec is used to find the field in structValue into which p should be loaded.
// prev is the set of property names already seen for structValue.
func (l *propertyLoader) loadOneElement(codec fields.List, structValue reflect.Value, p Property, prev map[string]struct{}) string {
var sliceOk bool
var sliceIndex int
var v reflect.Value
name := p.Name
fieldNames := strings.Split(name, ".")
for len(fieldNames) > 0 {
var field *fields.Field
// Start by trying to find a field with name. If none found,
// cut off the last field (delimited by ".") and find its parent
// in the codec.
// eg. for name "A.B.C.D", split off "A.B.C" and try to
// find a field in the codec with this name.
// Loop again with "A.B", etc.
for i := len(fieldNames); i > 0; i-- {
parent := strings.Join(fieldNames[:i], ".")
field = codec.Match(parent)
if field != nil {
fieldNames = fieldNames[i:]
break
}
}
// If we never found a matching field in the codec, return
// error message.
if field == nil {
return "no such struct field"
}
v = initField(structValue, field.Index)
if !v.IsValid() {
return "no such struct field"
}
if !v.CanSet() {
return "cannot set struct field"
}
// If field implements PLS, we delegate loading to the PLS's Load early,
// and stop iterating through fields.
ok, err := plsFieldLoad(v, p, fieldNames)
if err != nil {
return err.Error()
}
if ok {
return ""
}
if field.Type.Kind() == reflect.Ptr && field.Type.Elem().Kind() == reflect.Struct {
codec, err = structCache.Fields(field.Type.Elem())
if err != nil {
return err.Error()
}
// Init value if its nil
if v.IsNil() {
v.Set(reflect.New(field.Type.Elem()))
}
structValue = v.Elem()
}
if field.Type.Kind() == reflect.Struct {
codec, err = structCache.Fields(field.Type)
if err != nil {
return err.Error()
}
structValue = v
}
// If the element is a slice, we need to accommodate it.
if v.Kind() == reflect.Slice && v.Type() != typeOfByteSlice {
if l.m == nil {
l.m = make(map[string]int)
}
sliceIndex = l.m[p.Name]
l.m[p.Name] = sliceIndex + 1
for v.Len() <= sliceIndex {
v.Set(reflect.Append(v, reflect.New(v.Type().Elem()).Elem()))
}
structValue = v.Index(sliceIndex)
// If structValue implements PLS, we delegate loading to the PLS's
// Load early, and stop iterating through fields.
ok, err := plsFieldLoad(structValue, p, fieldNames)
if err != nil {
return err.Error()
}
if ok {
return ""
}
if structValue.Type().Kind() == reflect.Struct {
codec, err = structCache.Fields(structValue.Type())
if err != nil {
return err.Error()
}
}
sliceOk = true
}
}
var slice reflect.Value
if v.Kind() == reflect.Slice && v.Type().Elem().Kind() != reflect.Uint8 {
slice = v
v = reflect.New(v.Type().Elem()).Elem()
} else if _, ok := prev[p.Name]; ok && !sliceOk {
// Zero the field back out that was set previously, turns out
// it's a slice and we don't know what to do with it
v.Set(reflect.Zero(v.Type()))
return "multiple-valued property requires a slice field type"
}
prev[p.Name] = struct{}{}
if errReason := setVal(v, p); errReason != "" {
// Set the slice back to its zero value.
if slice.IsValid() {
slice.Set(reflect.Zero(slice.Type()))
}
return errReason
}
if slice.IsValid() {
slice.Index(sliceIndex).Set(v)
}
return ""
}
// plsFieldLoad first tries to converts v's value to a PLS, then v's addressed
// value to a PLS. If neither succeeds, plsFieldLoad returns false for first return
// value. Otherwise, the first return value will be true.
// If v is successfully converted to a PLS, plsFieldLoad will then try to Load
// the property p into v (by way of the PLS's Load method).
//
// If the field v has been flattened, the Property's name must be altered
// before calling Load to reflect the field v.
// For example, if our original field name was "A.B.C.D",
// and at this point in iteration we had initialized the field
// corresponding to "A" and have moved into the struct, so that now
// v corresponds to the field named "B", then we want to let the
// PLS handle this field (B)'s subfields ("C", "D"),
// so we send the property to the PLS's Load, renamed to "C.D".
//
// If subfields are present, the field v has been flattened.
func plsFieldLoad(v reflect.Value, p Property, subfields []string) (ok bool, err error) {
vpls, err := plsForLoad(v)
if err != nil {
return false, err
}
if vpls == nil {
return false, nil
}
// If Entity, load properties as well as key.
if e, ok := p.Value.(*Entity); ok {
err = loadEntity(vpls, e)
return true, err
}
// If flattened, we must alter the property's name to reflect
// the field v.
if len(subfields) > 0 {
p.Name = strings.Join(subfields, ".")
}
return true, vpls.Load([]Property{p})
}
// setVal sets 'v' to the value of the Property 'p'.
func setVal(v reflect.Value, p Property) (s string) {
pValue := p.Value
switch v.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
x, ok := pValue.(int64)
if !ok && pValue != nil {
return typeMismatchReason(p, v)
}
if v.OverflowInt(x) {
return overflowReason(x, v)
}
v.SetInt(x)
case reflect.Bool:
x, ok := pValue.(bool)
if !ok && pValue != nil {
return typeMismatchReason(p, v)
}
v.SetBool(x)
case reflect.String:
x, ok := pValue.(string)
if !ok && pValue != nil {
return typeMismatchReason(p, v)
}
v.SetString(x)
case reflect.Float32, reflect.Float64:
x, ok := pValue.(float64)
if !ok && pValue != nil {
return typeMismatchReason(p, v)
}
if v.OverflowFloat(x) {
return overflowReason(x, v)
}
v.SetFloat(x)
case reflect.Ptr:
// v must be a pointer to either a Key, an Entity, or one of the supported basic types.
if v.Type() != typeOfKeyPtr && v.Type().Elem().Kind() != reflect.Struct && !isValidPointerType(v.Type().Elem()) {
return typeMismatchReason(p, v)
}
if pValue == nil {
// If v is populated already, set it to nil.
if !v.IsNil() {
v.Set(reflect.New(v.Type()).Elem())
}
return ""
}
if x, ok := p.Value.(*Key); ok {
if _, ok := v.Interface().(*Key); !ok {
return typeMismatchReason(p, v)
}
v.Set(reflect.ValueOf(x))
return ""
}
if v.IsNil() {
v.Set(reflect.New(v.Type().Elem()))
}
switch x := pValue.(type) {
case *Entity:
err := loadEntity(v.Interface(), x)
if err != nil {
return err.Error()
}
case int64:
if v.Elem().OverflowInt(x) {
return overflowReason(x, v.Elem())
}
v.Elem().SetInt(x)
case float64:
if v.Elem().OverflowFloat(x) {
return overflowReason(x, v.Elem())
}
v.Elem().SetFloat(x)
case bool:
v.Elem().SetBool(x)
case string:
v.Elem().SetString(x)
case GeoPoint, time.Time:
v.Elem().Set(reflect.ValueOf(x))
default:
return typeMismatchReason(p, v)
}
case reflect.Struct:
switch v.Type() {
case typeOfTime:
// Some time values are converted into microsecond integer values
// (for example when used with projects). So, here we check first
// whether this value is an int64, and next whether it's time.
//
// See more at https://cloud.google.com/datastore/docs/concepts/queries#limitations_on_projections
micros, ok := pValue.(int64)
if ok {
s := micros / 1e6
ns := micros % 1e6
v.Set(reflect.ValueOf(time.Unix(s, ns)))
break
}
x, ok := pValue.(time.Time)
if !ok && pValue != nil {
return typeMismatchReason(p, v)
}
v.Set(reflect.ValueOf(x))
case typeOfGeoPoint:
x, ok := pValue.(GeoPoint)
if !ok && pValue != nil {
return typeMismatchReason(p, v)
}
v.Set(reflect.ValueOf(x))
default:
ent, ok := pValue.(*Entity)
if !ok {
return typeMismatchReason(p, v)
}
err := loadEntity(v.Addr().Interface(), ent)
if err != nil {
return err.Error()
}
}
case reflect.Slice:
x, ok := pValue.([]byte)
if !ok && pValue != nil {
return typeMismatchReason(p, v)
}
if v.Type().Elem().Kind() != reflect.Uint8 {
return typeMismatchReason(p, v)
}
v.SetBytes(x)
default:
return typeMismatchReason(p, v)
}
return ""
}
// initField is similar to reflect's Value.FieldByIndex, in that it
// returns the nested struct field corresponding to index, but it
// initialises any nil pointers encountered when traversing the structure.
func initField(val reflect.Value, index []int) reflect.Value {
for _, i := range index[:len(index)-1] {
val = val.Field(i)
if val.Kind() == reflect.Ptr {
if val.IsNil() {
val.Set(reflect.New(val.Type().Elem()))
}
val = val.Elem()
}
}
return val.Field(index[len(index)-1])
}
// loadEntityProto loads an EntityProto into PropertyLoadSaver or struct pointer.
func loadEntityProto(dst interface{}, src *pb.Entity) error {
ent, err := protoToEntity(src)
if err != nil {
return err
}
return loadEntity(dst, ent)
}
func loadEntity(dst interface{}, ent *Entity) error {
if pls, ok := dst.(PropertyLoadSaver); ok {
err := pls.Load(ent.Properties)
if err != nil {
return err
}
if e, ok := dst.(KeyLoader); ok {
err = e.LoadKey(ent.Key)
}
return err
}
return loadEntityToStruct(dst, ent)
}
func loadEntityToStruct(dst interface{}, ent *Entity) error {
pls, err := newStructPLS(dst)
if err != nil {
return err
}
// Try and load key.
keyField := pls.codec.Match(keyFieldName)
if keyField != nil && ent.Key != nil {
pls.v.FieldByIndex(keyField.Index).Set(reflect.ValueOf(ent.Key))
}
// Load properties.
return pls.Load(ent.Properties)
}
func (s structPLS) Load(props []Property) error {
var fieldName, errReason string
var l propertyLoader
prev := make(map[string]struct{})
for _, p := range props {
if errStr := l.load(s.codec, s.v, p, prev); errStr != "" {
// We don't return early, as we try to load as many properties as possible.
// It is valid to load an entity into a struct that cannot fully represent it.
// That case returns an error, but the caller is free to ignore it.
fieldName, errReason = p.Name, errStr
}
}
if errReason != "" {
return &ErrFieldMismatch{
StructType: s.v.Type(),
FieldName: fieldName,
Reason: errReason,
}
}
return nil
}
func protoToEntity(src *pb.Entity) (*Entity, error) {
props := make([]Property, 0, len(src.Properties))
for name, val := range src.Properties {
v, err := propToValue(val)
if err != nil {
return nil, err
}
props = append(props, Property{
Name: name,
Value: v,
NoIndex: val.ExcludeFromIndexes,
})
}
var key *Key
if src.Key != nil {
// Ignore any error, since nested entity values
// are allowed to have an invalid key.
key, _ = protoToKey(src.Key)
}
return &Entity{key, props}, nil
}
// propToValue returns a Go value that represents the PropertyValue. For
// example, a TimestampValue becomes a time.Time.
func propToValue(v *pb.Value) (interface{}, error) {
switch v := v.ValueType.(type) {
case *pb.Value_NullValue:
return nil, nil
case *pb.Value_BooleanValue:
return v.BooleanValue, nil
case *pb.Value_IntegerValue:
return v.IntegerValue, nil
case *pb.Value_DoubleValue:
return v.DoubleValue, nil
case *pb.Value_TimestampValue:
return time.Unix(v.TimestampValue.Seconds, int64(v.TimestampValue.Nanos)), nil
case *pb.Value_KeyValue:
return protoToKey(v.KeyValue)
case *pb.Value_StringValue:
return v.StringValue, nil
case *pb.Value_BlobValue:
return []byte(v.BlobValue), nil
case *pb.Value_GeoPointValue:
return GeoPoint{Lat: v.GeoPointValue.Latitude, Lng: v.GeoPointValue.Longitude}, nil
case *pb.Value_EntityValue:
return protoToEntity(v.EntityValue)
case *pb.Value_ArrayValue:
arr := make([]interface{}, 0, len(v.ArrayValue.Values))
for _, v := range v.ArrayValue.Values {
vv, err := propToValue(v)
if err != nil {
return nil, err
}
arr = append(arr, vv)
}
return arr, nil
default:
return nil, nil
}
}
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