335 lines
8.5 KiB
Go
335 lines
8.5 KiB
Go
// Copyright 2011 Google Inc. All rights reserved.
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// Use of this source code is governed by the Apache 2.0
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// license that can be found in the LICENSE file.
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package datastore
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import (
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"fmt"
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"reflect"
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"time"
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"google.golang.org/appengine"
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pb "google.golang.org/appengine/internal/datastore"
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)
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var (
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typeOfBlobKey = reflect.TypeOf(appengine.BlobKey(""))
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typeOfByteSlice = reflect.TypeOf([]byte(nil))
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typeOfByteString = reflect.TypeOf(ByteString(nil))
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typeOfGeoPoint = reflect.TypeOf(appengine.GeoPoint{})
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typeOfTime = reflect.TypeOf(time.Time{})
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)
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// typeMismatchReason returns a string explaining why the property p could not
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// be stored in an entity field of type v.Type().
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func typeMismatchReason(p Property, v reflect.Value) string {
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entityType := "empty"
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switch p.Value.(type) {
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case int64:
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entityType = "int"
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case bool:
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entityType = "bool"
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case string:
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entityType = "string"
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case float64:
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entityType = "float"
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case *Key:
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entityType = "*datastore.Key"
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case time.Time:
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entityType = "time.Time"
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case appengine.BlobKey:
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entityType = "appengine.BlobKey"
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case appengine.GeoPoint:
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entityType = "appengine.GeoPoint"
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case ByteString:
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entityType = "datastore.ByteString"
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case []byte:
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entityType = "[]byte"
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}
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return fmt.Sprintf("type mismatch: %s versus %v", entityType, v.Type())
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}
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type propertyLoader struct {
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// m holds the number of times a substruct field like "Foo.Bar.Baz" has
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// been seen so far. The map is constructed lazily.
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m map[string]int
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}
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func (l *propertyLoader) load(codec *structCodec, structValue reflect.Value, p Property, requireSlice bool) string {
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var v reflect.Value
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// Traverse a struct's struct-typed fields.
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for name := p.Name; ; {
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decoder, ok := codec.byName[name]
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if !ok {
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return "no such struct field"
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}
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v = structValue.Field(decoder.index)
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if !v.IsValid() {
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return "no such struct field"
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}
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if !v.CanSet() {
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return "cannot set struct field"
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}
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if decoder.substructCodec == nil {
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break
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}
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if v.Kind() == reflect.Slice {
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if l.m == nil {
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l.m = make(map[string]int)
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}
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index := l.m[p.Name]
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l.m[p.Name] = index + 1
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for v.Len() <= index {
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v.Set(reflect.Append(v, reflect.New(v.Type().Elem()).Elem()))
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}
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structValue = v.Index(index)
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requireSlice = false
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} else {
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structValue = v
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}
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// Strip the "I." from "I.X".
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name = name[len(codec.byIndex[decoder.index].name):]
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codec = decoder.substructCodec
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}
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var slice reflect.Value
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if v.Kind() == reflect.Slice && v.Type().Elem().Kind() != reflect.Uint8 {
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slice = v
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v = reflect.New(v.Type().Elem()).Elem()
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} else if requireSlice {
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return "multiple-valued property requires a slice field type"
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}
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// Convert indexValues to a Go value with a meaning derived from the
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// destination type.
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pValue := p.Value
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if iv, ok := pValue.(indexValue); ok {
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meaning := pb.Property_NO_MEANING
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switch v.Type() {
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case typeOfBlobKey:
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meaning = pb.Property_BLOBKEY
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case typeOfByteSlice:
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meaning = pb.Property_BLOB
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case typeOfByteString:
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meaning = pb.Property_BYTESTRING
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case typeOfGeoPoint:
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meaning = pb.Property_GEORSS_POINT
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case typeOfTime:
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meaning = pb.Property_GD_WHEN
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}
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var err error
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pValue, err = propValue(iv.value, meaning)
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if err != nil {
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return err.Error()
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}
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}
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switch v.Kind() {
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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x, ok := pValue.(int64)
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if !ok && pValue != nil {
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return typeMismatchReason(p, v)
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}
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if v.OverflowInt(x) {
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return fmt.Sprintf("value %v overflows struct field of type %v", x, v.Type())
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}
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v.SetInt(x)
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case reflect.Bool:
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x, ok := pValue.(bool)
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if !ok && pValue != nil {
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return typeMismatchReason(p, v)
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}
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v.SetBool(x)
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case reflect.String:
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switch x := pValue.(type) {
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case appengine.BlobKey:
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v.SetString(string(x))
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case ByteString:
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v.SetString(string(x))
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case string:
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v.SetString(x)
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default:
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if pValue != nil {
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return typeMismatchReason(p, v)
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}
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}
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case reflect.Float32, reflect.Float64:
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x, ok := pValue.(float64)
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if !ok && pValue != nil {
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return typeMismatchReason(p, v)
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}
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if v.OverflowFloat(x) {
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return fmt.Sprintf("value %v overflows struct field of type %v", x, v.Type())
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}
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v.SetFloat(x)
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case reflect.Ptr:
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x, ok := pValue.(*Key)
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if !ok && pValue != nil {
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return typeMismatchReason(p, v)
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}
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if _, ok := v.Interface().(*Key); !ok {
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return typeMismatchReason(p, v)
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}
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v.Set(reflect.ValueOf(x))
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case reflect.Struct:
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switch v.Type() {
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case typeOfTime:
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x, ok := pValue.(time.Time)
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if !ok && pValue != nil {
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return typeMismatchReason(p, v)
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}
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v.Set(reflect.ValueOf(x))
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case typeOfGeoPoint:
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x, ok := pValue.(appengine.GeoPoint)
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if !ok && pValue != nil {
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return typeMismatchReason(p, v)
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}
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v.Set(reflect.ValueOf(x))
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default:
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return typeMismatchReason(p, v)
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}
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case reflect.Slice:
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x, ok := pValue.([]byte)
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if !ok {
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if y, yok := pValue.(ByteString); yok {
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x, ok = []byte(y), true
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}
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}
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if !ok && pValue != nil {
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return typeMismatchReason(p, v)
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}
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if v.Type().Elem().Kind() != reflect.Uint8 {
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return typeMismatchReason(p, v)
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}
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v.SetBytes(x)
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default:
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return typeMismatchReason(p, v)
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}
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if slice.IsValid() {
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slice.Set(reflect.Append(slice, v))
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}
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return ""
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}
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// loadEntity loads an EntityProto into PropertyLoadSaver or struct pointer.
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func loadEntity(dst interface{}, src *pb.EntityProto) (err error) {
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props, err := protoToProperties(src)
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if err != nil {
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return err
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}
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if e, ok := dst.(PropertyLoadSaver); ok {
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return e.Load(props)
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}
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return LoadStruct(dst, props)
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}
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func (s structPLS) Load(props []Property) error {
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var fieldName, reason string
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var l propertyLoader
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for _, p := range props {
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if errStr := l.load(s.codec, s.v, p, p.Multiple); errStr != "" {
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// We don't return early, as we try to load as many properties as possible.
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// It is valid to load an entity into a struct that cannot fully represent it.
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// That case returns an error, but the caller is free to ignore it.
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fieldName, reason = p.Name, errStr
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}
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}
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if reason != "" {
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return &ErrFieldMismatch{
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StructType: s.v.Type(),
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FieldName: fieldName,
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Reason: reason,
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}
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}
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return nil
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}
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func protoToProperties(src *pb.EntityProto) ([]Property, error) {
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props, rawProps := src.Property, src.RawProperty
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out := make([]Property, 0, len(props)+len(rawProps))
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for {
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var (
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x *pb.Property
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noIndex bool
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)
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if len(props) > 0 {
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x, props = props[0], props[1:]
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} else if len(rawProps) > 0 {
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x, rawProps = rawProps[0], rawProps[1:]
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noIndex = true
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} else {
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break
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}
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var value interface{}
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if x.Meaning != nil && *x.Meaning == pb.Property_INDEX_VALUE {
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value = indexValue{x.Value}
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} else {
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var err error
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value, err = propValue(x.Value, x.GetMeaning())
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if err != nil {
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return nil, err
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}
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}
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out = append(out, Property{
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Name: x.GetName(),
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Value: value,
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NoIndex: noIndex,
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Multiple: x.GetMultiple(),
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})
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}
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return out, nil
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}
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// propValue returns a Go value that combines the raw PropertyValue with a
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// meaning. For example, an Int64Value with GD_WHEN becomes a time.Time.
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func propValue(v *pb.PropertyValue, m pb.Property_Meaning) (interface{}, error) {
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switch {
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case v.Int64Value != nil:
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if m == pb.Property_GD_WHEN {
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return fromUnixMicro(*v.Int64Value), nil
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} else {
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return *v.Int64Value, nil
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}
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case v.BooleanValue != nil:
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return *v.BooleanValue, nil
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case v.StringValue != nil:
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if m == pb.Property_BLOB {
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return []byte(*v.StringValue), nil
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} else if m == pb.Property_BLOBKEY {
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return appengine.BlobKey(*v.StringValue), nil
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} else if m == pb.Property_BYTESTRING {
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return ByteString(*v.StringValue), nil
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} else {
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return *v.StringValue, nil
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}
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case v.DoubleValue != nil:
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return *v.DoubleValue, nil
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case v.Referencevalue != nil:
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key, err := referenceValueToKey(v.Referencevalue)
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if err != nil {
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return nil, err
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}
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return key, nil
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case v.Pointvalue != nil:
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// NOTE: Strangely, latitude maps to X, longitude to Y.
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return appengine.GeoPoint{Lat: v.Pointvalue.GetX(), Lng: v.Pointvalue.GetY()}, nil
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}
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return nil, nil
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}
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// indexValue is a Property value that is created when entities are loaded from
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// an index, such as from a projection query.
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//
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// Such Property values do not contain all of the metadata required to be
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// faithfully represented as a Go value, and are instead represented as an
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// opaque indexValue. Load the properties into a concrete struct type (e.g. by
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// passing a struct pointer to Iterator.Next) to reconstruct actual Go values
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// of type int, string, time.Time, etc.
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type indexValue struct {
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value *pb.PropertyValue
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}
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