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// Copyright 2014 Canonical Ltd.
// Licensed under the LGPLv3, see LICENCE file for details.
package filestorage
import (
"github.com/juju/errors"
)
// Convert turns a Document into a Metadata if possible.
func Convert(doc Document) (Metadata, error) {
meta, ok := doc.(Metadata)
if !ok {
return nil, errors.Errorf("expected a Metadata doc, got %v", doc)
}
return meta, nil
}
// MetadataDocStorage provides the MetadataStorage methods than can be
// derived from DocStorage methods. To fully implement MetadataStorage,
// this type must be embedded in a type that implements the remaining
// methods.
type MetadataDocStorage struct {
DocStorage
}
// Metadata implements MetadataStorage.Metadata.
func (s *MetadataDocStorage) Metadata(id string) (Metadata, error) {
doc, err := s.Doc(id)
if err != nil {
return nil, errors.Trace(err)
}
meta, err := Convert(doc)
return meta, errors.Trace(err)
}
// ListMetadata implements MetadataStorage.ListMetadata.
func (s *MetadataDocStorage) ListMetadata() ([]Metadata, error) {
docs, err := s.ListDocs()
if err != nil {
return nil, errors.Trace(err)
}
var metaList []Metadata
for _, doc := range docs {
if doc == nil {
continue
}
meta, err := Convert(doc)
if err != nil {
return nil, errors.Trace(err)
}
metaList = append(metaList, meta)
}
return metaList, nil
}
// ListMetadata implements MetadataStorage.ListMetadata.
func (s *MetadataDocStorage) AddMetadata(meta Metadata) (string, error) {
id, err := s.AddDoc(meta)
return id, errors.Trace(err)
}
// ListMetadata implements MetadataStorage.ListMetadata.
func (s *MetadataDocStorage) RemoveMetadata(id string) error {
return errors.Trace(s.RemoveDoc(id))
}
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