Add binding result streaming to client (#430)

* Add binding result streaming to client

* Remove spaces around assignment

* Satisfy the linting gods

* Fix streaming field

* Rename? Or copy...

* Put back original test

Author: GavinMendelGleason

terminusdb_client/client/Client.py

@@ -31,6 +31,36 @@
 # summary Python module for accessing the Terminus DB API
 
 
+class WoqlResult:
+    """Iterator for streaming WOQL results."""
+    def __init__(self, lines):
+        preface = json.loads(next(lines))
+        if not ('@type' in preface and preface['@type'] == 'PrefaceRecord'):
+            raise DatabaseError(response=preface)
+        self.preface = preface
+        self.postscript = {}
+        self.lines = lines
+
+    def _check_error(self, document):
+        if ('@type' in document):
+            if document['@type'] == 'Binding':
+                return document
+            if document['@type'] == 'PostscriptRecord':
+                self.postscript = document
+                raise StopIteration()
+
+        raise DatabaseError(response=document)
+
+    def variable_names(self):
+        return self.preface['names']
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        return self._check_error(json.loads(next(self.lines)))
+
+
 class JWTAuth(requests.auth.AuthBase):
     """Class for JWT Authentication in requests"""
 
@@ -1500,8 +1530,9 @@ def query(
         commit_msg: Optional[str] = None,
         get_data_version: bool = False,
         last_data_version: Optional[str] = None,
+        streaming: bool = False,
         # file_dict: Optional[dict] = None,
-    ) -> Union[dict, str]:
+    ) -> Union[dict, str, WoqlResult]:
         """Updates the contents of the specified graph with the triples encoded in turtle format Replaces the entire graph contents
 
         Parameters
@@ -1537,6 +1568,7 @@ def query(
         else:
             request_woql_query = woql_query
         query_obj["query"] = request_woql_query
+        query_obj["streaming"] = streaming
 
         headers = self._default_headers.copy()
         if last_data_version is not None:
@@ -1547,7 +1579,12 @@ def query(
             headers=headers,
             json=query_obj,
             auth=self._auth(),
+            stream=streaming
         )
+
+        if streaming:
+            return WoqlResult(lines=_finish_response(result, streaming=True))
+
         if get_data_version:
             result, version = _finish_response(result, get_data_version)
             result = json.loads(result)

terminusdb_client/tests/test_Client.py

@@ -234,6 +234,7 @@ def test_query(mocked_requests, mocked_requests2, mocked_requests3):
             "query": WoqlStar,
         },
         headers={"user-agent": f"terminusdb-client-python/{__version__}"},
+        stream=False
     )
 
 

terminusdb_client/woql_utils.py

@@ -24,7 +24,7 @@ def _args_as_payload(args: dict) -> dict:
     return {k: v for k, v in args.items() if v}
 
 
-def _finish_response(request_response, get_version=False):
+def _finish_response(request_response, get_version=False, streaming=False):
     """Get the response text
 
     Parameters
@@ -43,11 +43,14 @@ def _finish_response(request_response, get_version=False):
 
     """
     if request_response.status_code == 200:
-        if get_version:
+        if get_version and not streaming:
             return request_response.text, request_response.headers.get(
                 "Terminusdb-Data-Version"
             )
-        return request_response.text  # if not a json it raises an error
+        if streaming:
+            return request_response.iter_lines()
+        else:
+            return request_response.text  # if not a json it raises an error
     elif request_response.status_code > 399 and request_response.status_code < 599:
         raise DatabaseError(request_response)
 

terminusdb_client/woqlquery/woql_query.py

@@ -367,21 +367,22 @@ def _clean_subject(self, obj):
             return self._expand_node_variable(obj)
         raise ValueError("Subject must be a URI string")
 
-    def _clean_predicate(self, predicate):
+    def _clean_predicate(self, obj):
         """Transforms whatever is passed in as the predicate (id or variable) into the appropriate json-ld form"""
         pred = False
-        if isinstance(predicate, dict):
-            return predicate
-        if not isinstance(predicate, str):
-            raise ValueError("Predicate must be a URI string")
-            return str(predicate)
-        if ":" in predicate:
-            pred = predicate
-        elif self._vocab and (predicate in self._vocab):
-            pred = self._vocab[predicate]
-        else:
-            pred = predicate
-        return self._expand_node_variable(pred)
+        if type(obj) is dict:
+            return obj
+        elif type(obj) is str:
+            if ":" in obj:
+                pred = obj
+            elif self._vocab and (obj in self._vocab):
+                pred = self._vocab[obj]
+            else:
+                pred = obj
+            return self._expand_node_variable(pred)
+        elif isinstance(obj, Var):
+            return self._expand_node_variable(obj)
+        raise ValueError("Predicate must be a URI string")
 
     def _clean_path_predicate(self, predicate=None):
         pred = False