added parameters support (#56)

* added parameters support

* fixed PR comments

Author: DvirDukhan

README.md

@@ -41,6 +41,17 @@ result = redis_graph.query(query)
 # Print resultset
 result.pretty_print()
 
+# Use parameters
+params = {'purpose':"pleasure"}
+query = """MATCH (p:person)-[v:visited {purpose:$purpose}]->(c:country)
+		   RETURN p.name, p.age, v.purpose, c.name"""
+
+result = redis_graph.query(query, params)
+
+# Print resultset
+result.pretty_print()
+
+
 # Iterate through resultset
 for record in result.result_set:
 	person_name = record[0]

redisgraph/graph.py

@@ -103,12 +103,30 @@ def flush(self):
         self.nodes = {}
         self.edges = []
 
-    def query(self, q):
+    def build_params_header(self, params):
+        assert type(params) == dict
+        # Header starts with "CYPHER"
+        params_header = "CYPHER "
+        for key, value in params.items():
+            # If value is string add quotation marks.
+            if type(value) == str:
+                value = quote_string(value)
+            # Value is None, replace with "null" string.
+            elif value is None:
+                value = "null"
+            params_header += str(key) + "=" + str(value) + " "
+        return params_header
+
+    def query(self, q, params=None):
         """
         Executes a query against the graph.
         """
+        if params is not None:
+            q = self.build_params_header(params) + q
+
         statistics = None
         result_set = None
+
         response = self.redis_con.execute_command("GRAPH.QUERY", self.name, q, "--compact")
         return QueryResult(self, response)
 

test.py

@@ -94,6 +94,18 @@ def test_path(self):
         # All done, remove graph.
         redis_graph.delete()
 
+    def test_param(self):
+        redis_graph = Graph('params', self.r)
+
+        params = [1, 2.3, "str", True, False, None, [0, 1, 2]]
+        query = "RETURN $param"
+        for param in params:
+            result = redis_graph.query(query, {'param': param})
+            expected_results = [[param]]
+            self.assertEqual(expected_results, result.result_set)
+
+        # All done, remove graph.
+        redis_graph.delete()
 
 if __name__ == '__main__':
 	unittest.main()