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Add intelligent type marshalling/unmarshalling
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parent
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commit
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111
pkg/api/helper.go
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111
pkg/api/helper.go
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/*
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Copyright 2014 Google Inc. All rights reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package api
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import (
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"encoding/json"
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"fmt"
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"reflect"
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)
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var knownTypes = map[string]reflect.Type{}
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func init() {
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types := []interface{}{
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PodList{}, Pod{}, ReplicationControllerList{},
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ReplicationController{}, ServiceList{}, Service{},
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}
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for _, obj := range types {
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t := reflect.TypeOf(obj)
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knownTypes[t.Name()] = t
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}
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}
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// Returns the name of the type (sans pointer), and its kind field. Takes pointer-to-struct..
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func nameAndJSONBase(obj interface{}) (string, reflect.Value, error) {
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v := reflect.ValueOf(obj)
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if v.Kind() != reflect.Ptr {
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return "", reflect.Value{}, fmt.Errorf("expected pointer, but got %v", v.Type().Name())
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}
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v = v.Elem()
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name := v.Type().Name()
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if v.Kind() != reflect.Struct {
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return "", reflect.Value{}, fmt.Errorf("expected struct, but got %v", name)
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}
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jsonBase := v.FieldByName("JSONBase")
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if !jsonBase.IsValid() {
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return "", reflect.Value{}, fmt.Errorf("struct %v lacks embedded JSON type", name)
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}
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return name, jsonBase, nil
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}
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// Encode turns the given api object into an appropriate JSON string.
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// Will return an error if the object doesn't have an embedded JSONBase.
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// Obj must be a pointer to a struct. Note, this sets the object's Kind
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// field.
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func Encode(obj interface{}) (data []byte, err error) {
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name, jsonBase, err := nameAndJSONBase(obj)
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if err != nil {
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return nil, err
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}
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if _, contains := knownTypes[name]; !contains {
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return nil, fmt.Errorf("struct %v can't be unmarshalled because it's not in knownTypes", name)
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}
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jsonBase.FieldByName("Kind").Set(reflect.ValueOf(name))
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return json.Marshal(obj)
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}
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// Decode converts a JSON string back into a pointer to an api object. Deduces the type
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// based upon the Kind field (set by encode).
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func Decode(data []byte) (interface{}, error) {
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findKind := struct {
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Kind string `json:"kind,omitempty" yaml:"kind,omitempty"`
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}{}
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err := json.Unmarshal(data, &findKind)
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if err != nil {
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return nil, fmt.Errorf("Couldn't get kind: %#v", err)
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}
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objType, found := knownTypes[findKind.Kind]
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if !found {
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return nil, fmt.Errorf("%v is not a known type", findKind.Kind)
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}
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obj := reflect.New(objType).Interface()
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err = json.Unmarshal(data, obj)
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if err != nil {
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return nil, err
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}
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return obj, nil
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}
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// DecodeInto parses a JSON string and stores it in obj. Returns an error
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// if data.Kind is set and doesn't match the type of obj. Obj should be a
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// pointer to an api type.
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func DecodeInto(data []byte, obj interface{}) error {
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err := json.Unmarshal(data, obj)
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if err != nil {
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return err
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}
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name, jsonBase, err := nameAndJSONBase(obj)
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if err != nil {
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return err
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}
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foundName := jsonBase.FieldByName("Kind").Interface().(string)
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if foundName != "" && foundName != name {
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return fmt.Errorf("data had kind %v, but passed object was of type %v", foundName, name)
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}
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return nil
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}
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74
pkg/api/helper_test.go
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74
pkg/api/helper_test.go
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@ -0,0 +1,74 @@
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/*
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Copyright 2014 Google Inc. All rights reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package api
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import (
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"reflect"
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"testing"
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)
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func runTest(t *testing.T, source interface{}) {
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name := reflect.TypeOf(source).Name()
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data, err := Encode(source)
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if err != nil {
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t.Errorf("%v: %v", name, err)
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return
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}
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obj2, err := Decode(data)
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if err != nil {
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t.Errorf("%v: %v", name, err)
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return
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}
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if !reflect.DeepEqual(source, obj2) {
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t.Errorf("%v: wanted %#v, got %#v", name, source, obj2)
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return
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}
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obj3 := reflect.New(reflect.TypeOf(source).Elem()).Interface()
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err = DecodeInto(data, obj3)
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if err != nil {
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t.Errorf("%v: %v", name, err)
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return
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}
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if !reflect.DeepEqual(source, obj3) {
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t.Errorf("%v: wanted %#v, got %#v", name, source, obj3)
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return
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}
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}
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func TestTypes(t *testing.T) {
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// TODO: auto-fill all fields.
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table := []interface{}{
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&Pod{
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JSONBase: JSONBase{
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ID: "mylittlepod",
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},
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Labels: map[string]string{
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"name": "pinky",
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},
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},
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&Service{},
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&ServiceList{},
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&ReplicationControllerList{},
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&ReplicationController{},
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&PodList{},
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}
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for _, item := range table {
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runTest(t, item)
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}
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}
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// TODO: test rejection of bad JSON.
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