add logging (#27)

openaq/__init__.py

@@ -1,8 +1,15 @@
 """OpenAQ Python SDK."""
 
+import logging
+
+
 __version__ = "0.3.0"
 
 
+logger = logging.getLogger("openaq")
+logger.addHandler(logging.NullHandler())
+
+
 from ._async.client import AsyncOpenAQ as AsyncOpenAQ
 from ._sync.client import OpenAQ as OpenAQ
 from .shared.exceptions import (

openaq/shared/client.py

@@ -3,12 +3,15 @@
 import os
 import platform
 from abc import ABC, abstractmethod
+import logging
 from pathlib import Path
 from typing import Any, Mapping, Union
 
 from openaq._sync.transport import Transport
 from openaq._async.transport import AsyncTransport
 
+logger = logging.getLogger('openaq')
+
 # for Python versions <3.11 tomllib is not part of std. library
 _has_toml = True
 try:
@@ -73,6 +76,12 @@ def __init__(
         self._user_agent = user_agent
         self.resolve_headers()
 
+    def _check_api_key_url(self):
+        if not self.api_key and self.base_url == DEFAULT_BASE_URL:
+            logger.warning(
+                "API key not set: An API key is required when using the OpenAQ API"
+            )
+
     def _get_api_key(self) -> str:
         """Gets API key value from env or openaq config file.