further support for using no SentenceTransformer

pylib/__about__.py

@@ -3,4 +3,4 @@
 # SPDX-License-Identifier: Apache-2.0
 # ogbujipt.about
 
-__version__ = "0.5.0"
+__version__ = "0.5.1"

pylib/embedding_helper.py

@@ -110,18 +110,17 @@ def __init__(self, embedding_model, conn):
             See the main docstring (or run `help(pgvector_connection)`)
         '''
         # Check if the provided embedding model is a SentenceTransformer
-        if embedding_model.__class__.__name__ == 'SentenceTransformer':
+        if (embedding_model.__class__.__name__ == 'SentenceTransformer') and (not None):
             self._embedding_model = embedding_model
+            self._embed_dimension = len(self._embedding_model.encode(''))
+        elif embedding_model is None:
+            self._embedding_model = None
+            self._embed_dimension = 0
         else:
-            raise ValueError('embedding_model must be a SentenceTransformer object')
+            raise ValueError('embedding_model must be a SentenceTransformer object or None')
 
         self.conn = conn
 
-        if self._embedding_model:  # if self.embedding_model is none, don't try to measure dimensionality
-            self._embed_dimension = len(self._embedding_model.encode(''))
-        else:
-            self._embed_dimension = 0
-
     @classmethod
     async def create(
             cls,