feat: add platform-collection relationship in platform.FetchCollection()

pkg/collection.go

@@ -10,9 +10,13 @@ type default_collection struct {
 	platform_name string
 }
 
-func (collection *default_collection) ToNode() (string, []byte, error) {
+func (collection *default_collection) GetClass() string {
 	platform_name := strings.ToUpper(collection.platform_name)
-	return platform_name + "_DEFAULT", nil, nil
+	return platform_name + "_DEFAULT"
+}
+
+func (collection *default_collection) GetMetadata() []byte {
+	return nil
 }
 
 func (collection *default_collection) FromNode(_class string, name string, metadata []byte) error {
@@ -46,13 +50,19 @@ func NewCollection(name string, metadata []byte) *Collection {
 }
 
 // Internal RelationshipClass to handle the collection to node relationship
-type collection_relation struct{}
-
-func (collection *collection_relation) ToRelationship() (string, []byte, error) {
-	return "COLLECTION_HAS", nil, nil
+type collection_has_node struct {
+	Relationship
 }
 
-func (collection *collection_relation) FromRelationship(_class string, metadata []byte) error {
+func (col_has_node *collection_has_node) GetClass() string {
+	return "COLLECTION_HAS"
+}
+
+func (col_has_node *collection_has_node) GetMetadata() []byte {
+	return nil
+}
+
+func (col_has_node *collection_has_node) FromRelationship(_class string, metadata []byte) error {
 	if _class != "COLLECTION_HAS" {
 		return fmt.Errorf("invalid class %s", _class)
 	}
@@ -62,7 +72,7 @@ func (collection *collection_relation) FromRelationship(_class string, metadata
 // Adds a new child to this collection. Use the underlaying node's AddRelation
 // method.
 func (collection *Collection) AddChild(node *Node) error {
-	_, err := collection.AddRelation(&collection_relation{}, node.Id)
+	_, err := collection.StoreRelation(&collection_has_node{}, node.Id)
 	if err != nil {
 		return err
 	}