add is_number validator

api/validators.py

@@ -10,6 +10,21 @@ def validate_keys_exists(obj, *keys):
     return True
 
 
+def is_number(s):
+    try:
+        float(s)
+        return True
+    except ValueError:
+        return False
+
+
+def validate_number(*values):
+    for val in values:
+        if not is_number(val):
+            raise ValidationError('{} is not a number'.format(val))
+    return True
+
+
 def validate_territory(value):
     for market in iter_markets():
         if market.territory == value: