Allow input and output of nested entities (CMEM-4492) (#4)

* Allow input and output of nested entities.

* Add is_uri property to EntityPath

* change log

* fix safety issue

---------

Co-authored-by: Sebastian Tramp <[email protected]>

CHANGELOG.md

@@ -4,6 +4,13 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](http://keepachangelog.com/) and this project adheres to [Semantic Versioning](https://semver.org/)
 
+## [Unreleased]
+
+### Added
+
+- capabilities for hierarchical entities as input and output of workflow tasks
+
+
 ## [4.3.0] 2023-10-20
 
 ### Added

cmem_plugin_base/dataintegration/entity.py

@@ -1,27 +1,35 @@
 """Instance of any given concept."""
-from typing import Sequence, Iterator
+from typing import Sequence, Iterator, Optional
 
 
 class EntityPath:
     """A path in a schema.
 
     :param path: The path string using the Silk path language.
+    :param is_uri: If true, values for this path must only contain URIs that point to
+    a sub entity.
     """
 
-    def __init__(self, path: str) -> None:
+    def __init__(self, path: str, is_uri: bool = False) -> None:
         self.path = path
+        self.is_uri = is_uri
 
 
 class EntitySchema:
     """An entity schema.
 
     :param type_uri: The entity type
     :param paths: Ordered list of paths
+    :param sub_path: Path starting from the root for enumerating the entities.
     """
 
-    def __init__(self, type_uri: str, paths: Sequence[EntityPath]) -> None:
+    def __init__(self,
+                 type_uri: str,
+                 paths: Sequence[EntityPath],
+                 sub_path: EntityPath = EntityPath("")) -> None:
         self.type_uri = type_uri
         self.paths = paths
+        self.sub_path = sub_path
 
 
 class Entity:
@@ -45,8 +53,13 @@ class Entities:
     :param entities: An iterable collection of entities. May be very large, so it
         should be iterated over and not loaded into memory at once.
     :param schema: All entities conform to this entity schema.
+    :param sub_entities Additional entity collections.
     """
 
-    def __init__(self, entities: Iterator[Entity], schema: EntitySchema) -> None:
+    def __init__(self,
+                 entities: Iterator[Entity],
+                 schema: EntitySchema,
+                 sub_entities: Optional[Sequence['Entities']] = None) -> None:
         self.entities = entities
         self.schema = schema
+        self.sub_entities = sub_entities