Separate generic parts of api library into conversion package.

pkg/conversion/decode.go

@@ -0,0 +1,129 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+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 conversion
+
+import (
+	"fmt"
+
+	"gopkg.in/v1/yaml"
+)
+
+// Decode converts a YAML or JSON string back into a pointer to an api object.
+// Deduces the type based upon the fields added by the MetaInsertionFactory
+// technique. The object will be converted, if necessary, into the
+// s.InternalVersion type before being returned. Decode will refuse to decode
+// objects without a version, because that's probably an error.
+func (s *Scheme) Decode(data []byte) (interface{}, error) {
+	version, kind, err := s.DataAPIVersionAndKind(data)
+	if err != nil {
+		return nil, err
+	}
+	if version == "" {
+		return nil, fmt.Errorf("API Version not set in '%s'", string(data))
+	}
+	obj, err := s.NewObject(version, kind)
+	if err != nil {
+		return nil, err
+	}
+	// yaml is a superset of json, so we use it to decode here. That way,
+	// we understand both.
+	err = yaml.Unmarshal(data, obj)
+	if err != nil {
+		return nil, err
+	}
+
+	// Version and Kind should be blank in memory.
+	blankVersionAndKind := s.MetaInsertionFactory.Create("", "")
+	err = s.converter.Convert(blankVersionAndKind, obj, SourceToDest|IgnoreMissingFields|AllowDifferentFieldNames)
+	if err != nil {
+		return nil, err
+	}
+
+	// Convert if needed.
+	if s.InternalVersion != version {
+		objOut, err := s.NewObject(s.InternalVersion, kind)
+		if err != nil {
+			return nil, err
+		}
+		err = s.converter.Convert(obj, objOut, 0)
+		if err != nil {
+			return nil, err
+		}
+		obj = objOut
+	}
+	return obj, nil
+}
+
+// DecodeInto parses a YAML or JSON string and stores it in obj. Returns an error
+// if data.Kind is set and doesn't match the type of obj. Obj should be a
+// pointer to an api type.
+// If obj's APIVersion doesn't match that in data, an attempt will be made to convert
+// data into obj's version.
+func (s *Scheme) DecodeInto(data []byte, obj interface{}) error {
+	dataVersion, dataKind, err := s.DataAPIVersionAndKind(data)
+	if err != nil {
+		return err
+	}
+	objVersion, objKind, err := s.ObjectAPIVersionAndKind(obj)
+	if err != nil {
+		return err
+	}
+	if dataKind == "" {
+		// Assume objects with unset Kind fields are being unmarshalled into the
+		// correct type.
+		dataKind = objKind
+	}
+	if dataKind != objKind {
+		return fmt.Errorf("data of kind '%v', obj of type '%v'", dataKind, objKind)
+	}
+	if dataVersion == "" {
+		// Assume objects with unset Version fields are being unmarshalled into the
+		// correct type.
+		dataVersion = objVersion
+	}
+
+	if objVersion == dataVersion {
+		// Easy case!
+		err = yaml.Unmarshal(data, obj)
+		if err != nil {
+			return err
+		}
+	} else {
+		external, err := s.NewObject(dataVersion, dataKind)
+		if err != nil {
+			return fmt.Errorf("Unable to create new object of type ('%s', '%s')", dataVersion, dataKind)
+		}
+		// yaml is a superset of json, so we use it to decode here. That way,
+		// we understand both.
+		err = yaml.Unmarshal(data, external)
+		if err != nil {
+			return err
+		}
+		err = s.converter.Convert(external, obj, 0)
+		if err != nil {
+			return err
+		}
+	}
+
+	// Version and Kind should be blank in memory.
+	blankVersionAndKind := s.MetaInsertionFactory.Create("", "")
+	err = s.converter.Convert(blankVersionAndKind, obj, SourceToDest|IgnoreMissingFields|AllowDifferentFieldNames)
+	if err != nil {
+		return err
+	}
+	return nil
+}