[errors] Validate arguments to get_dataframe

tiingo/api.py

@@ -1,15 +1,16 @@
 # -*- coding: utf-8 -*-
 
-import os
-import sys
-import pkg_resources
+from collections import namedtuple
 import csv
 import json
-from collections import namedtuple
-from zipfile import ZipFile
-from tiingo.restclient import RestClient
-import requests
+import os
 import re
+import sys
+import pkg_resources
+from zipfile import ZipFile
+
+from tiingo.restclient import RestClient
+from tiingo.exceptions import InstallPandasException, APIColumnNameError, InvalidFrequencyError, MissingRequiredArgumentError
 
 try:
     import pandas as pd
@@ -49,17 +50,6 @@ def dict_to_object(item, object_name):
                       object_hook=lambda d:
                       namedtuple(object_name, fields)(*values))
 
-class InstallPandasException(Exception):
-    pass
-
-
-class APIColumnNameError(Exception):
-    pass
-
-
-class InvalidFrequencyError(Exception):
-    pass
-
 
 class TiingoClient(RestClient):
     """Class for managing interactions with the Tiingo REST API
@@ -227,12 +217,16 @@ class TiingoClient(RestClient):
                 frequency (string): Resample frequency (defaults to daily).
         """
 
-        valid_columns = ['open', 'high', 'low', 'close', 'volume', 'adjOpen', 'adjHigh', 'adjLow',
-                         'adjClose', 'adjVolume', 'divCash', 'splitFactor']
+        valid_columns = {'open', 'high', 'low', 'close', 'volume', 'adjOpen', 'adjHigh', 'adjLow',
+                         'adjClose', 'adjVolume', 'divCash', 'splitFactor'}
 
         if metric_name is not None and metric_name not in valid_columns:
             raise APIColumnNameError('Valid data items are: ' + str(valid_columns))
 
+        if metric_name is None and type(tickers) is not str:
+            raise MissingRequiredArgumentError("""When tickers is provided as a list, metric_name is a required argument.
+            Please provide a metric_name, or call this method with one ticker at a time.""")
+
         params = {
             'format': 'json',
             'resampleFreq': frequency

tiingo/exceptions.py

@@ -0,0 +1,15 @@
+# Exception Clasess
+class InstallPandasException(Exception):
+    pass
+
+
+class APIColumnNameError(Exception):
+    pass
+
+
+class InvalidFrequencyError(Exception):
+    pass
+
+
+class MissingRequiredArgumentError(Exception):
+    pass