graph schema migration

1 files changed, 24 insertions, 0 deletions

diff --git a/bsfs/graph/graph.py b/bsfs/graph/graph.py
index 71973c2..4a36ff6 100644
--- a/bsfs/graph/graph.py
+++ b/bsfs/graph/graph.py
@@ -5,6 +5,7 @@ A copy of the license is provided with the project.
 Author: Matthias Baumgartner, 2022
 """
 # imports
+import os
 import typing
 
 # bsfs imports
@@ -35,6 +36,8 @@ class Graph():
     def __init__(self, backend: TripleStoreBase, user: URI):
         self._backend = backend
         self._user = user
+        # ensure Graph schema requirements
+        self.migrate(self._backend.schema)
 
     def __hash__(self) -> int:
         return hash((type(self), self._backend, self._user))
@@ -55,7 +58,28 @@ class Graph():
         """Return the store's local schema."""
         return self._backend.schema
 
+    def migrate(self, schema: Schema, append: bool = True) -> 'Graph':
+        """Migrate the current schema to a new *schema*.
+
+        Appends to the current schema by default; control this via *append*.
+        The `Graph` may add additional classes to the schema that are required for its interals.
+
         """
+        # check args
+        if not isinstance(schema, Schema):
+            raise TypeError(schema)
+        # append to current schema
+        if append:
+            schema = schema + self._backend.schema
+        # add Graph schema requirements
+        with open(os.path.join(os.path.dirname(__file__), 'schema.nt'), mode='rt', encoding='UTF-8') as ifile:
+            schema = schema + Schema.from_string(ifile.read())
+        # migrate schema in backend
+        # FIXME: consult access controls!
+        self._backend.schema = schema
+        # return self
+        return self
+
     def nodes(self, node_type: URI, guids: typing.Iterable[URI]) -> _nodes.Nodes:
         """
         node_type = self.schema.node(node_type)