obj_or_str fix #715

canvasapi/util.py

@@ -133,37 +133,34 @@ def obj_or_id(parameter, param_name, object_types):
         raise TypeError(message)
 
 
-def obj_or_str(obj, attr, object_types):
+def obj_or_str(parameter, param_name, object_types):
     """
-    Accepts an object. If the object has the attribute, return the
+    Accepts either an object or a string. If it is a string, return it directly.
+    If it is an object and the object is of correct type, return the object's
     corresponding string. Otherwise, throw an exception.
 
-    :param obj: object from which to retrieve attribute
-    :type obj: object
-    :param attr: name of the attribute to retrieve
-    :type attr: str
+    :param parameter: object from which to retrieve attribute
+    :type parameter: str or object
+    :param param_name: name of the attribute to retrieve
+    :type param_name: str
     :param object_types: tuple containing the types of the object being passed in
     :type object_types: tuple
     :rtype: str
     """
-    try:
-        return str(getattr(obj, attr))
-    except (AttributeError, TypeError):
-        if not isinstance(attr, str):
-            raise TypeError(
-                "Atttibute parameter {} must be of type string".format(attr)
-            )
-        for obj_type in object_types:
-            if isinstance(obj, obj_type):
-                try:
-                    return str(getattr(obj, attr))
-                except AttributeError:
-                    raise AttributeError("{} object does not have {} attribute").format(
-                        obj, attr
-                    )
+    if isinstance(parameter, str):
+        return parameter
 
-        obj_type_list = ",".join([obj_type.__name__ for obj_type in object_types])
-        raise TypeError("Parameter {} must be of type {}.".format(obj, obj_type_list))
+    for obj_type in object_types:
+        if isinstance(parameter, obj_type):
+            try:
+                return str(getattr(parameter, param_name))
+            except AttributeError:
+                raise AttributeError("{} object does not have {} attribute").format(
+                    parameter, param_name
+                )
+
+    obj_type_list = ",".join([obj_type.__name__ for obj_type in object_types])
+    raise TypeError("Parameter {} must be of type {}.".format(parameter, obj_type_list))
 
 
 def get_institution_url(base_url):

tests/test_util.py

@@ -431,6 +431,12 @@ def test_obj_or_id_nonuser_self(self, m):
             obj_or_id("self", "user_id", (CourseNickname,))
 
     # obj_or_str()
+    def test_obj_or_str_str(self, m):
+        name = obj_or_str("test", "name", (User,))
+
+        self.assertIsInstance(name, str)
+        self.assertEqual(name, "test")
+
     def test_obj_or_str_obj_attr(self, m):
         register_uris({"user": ["get_by_id"]}, m)
 
@@ -467,8 +473,12 @@ def test_obj_or_str_invalid_attr_parameter(self, m):
             obj_or_str(user, user, (User,))
 
     def test_obj_or_str_invalid_obj_type(self, m):
+        register_uris({"course": ["get_by_id"]}, m)
+
+        course = self.canvas.get_course(1)
+
         with self.assertRaises(TypeError):
-            obj_or_str("user", "name", (User,))
+            obj_or_str(course, "name", (User,))
 
     # get_institution_url()
     def test_get_institution_url(self, m):