oc.env converts none-string inputs to string instead of raising an ex…

…ception (#659)

docs/notebook/Tutorial.ipynb

@@ -774,8 +774,8 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "You can specify a default value to use in case the environment variable is not defined.\n",
-    "This default value can be a string or ``null`` (representing Python ``None``). Passing a default with a different type will result in an error.\n",
+    "You can specify a default value to use in case the environment variable is not set.\n",
+    "In such a case, the default value is converted to a string using ``str(default)``, unless it is ``null`` (representing Python ``None``) - in which case ``None`` is returned. \n",
     "\n",
     "The following example falls back to default passwords when ``DB_PASSWORD`` is not defined:"
    ]
@@ -789,23 +789,25 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "'abc123'\n",
-      "'12345'\n"
+      "'password'\n",
+      "'12345'\n",
+      "None\n"
      ]
     }
    ],
    "source": [
-    "os.environ.pop('DB_PASSWORD', None)  # ensure env variable does not exist\n",
     "cfg = OmegaConf.create(\n",
     "    {\n",
     "        \"database\": {\n",
-    "            \"password1\": \"${oc.env:DB_PASSWORD,abc123}\",  # the string 'abc123'\n",
-    "            \"password2\": \"${oc.env:DB_PASSWORD,'12345'}\",  # the string '12345'\n",
+    "            \"password1\": \"${oc.env:DB_PASSWORD,password}\",\n",
+    "            \"password2\": \"${oc.env:DB_PASSWORD,12345}\",\n",
+    "            \"password3\": \"${oc.env:DB_PASSWORD,null}\",\n",
     "        },\n",
     "    }\n",
     ")\n",
     "print(repr(cfg.database.password1))\n",
-    "print(repr(cfg.database.password2))"
+    "print(repr(cfg.database.password2))\n",
+    "print(repr(cfg.database.password3))"
    ]
   },
   {

docs/source/usage.rst

@@ -403,24 +403,31 @@ Input YAML file:
     >>> conf.user.home
     '/home/omry'
 
-You can specify a default value to use in case the environment variable is not defined.
-This default value can be a string or ``null`` (representing Python ``None``). Passing a default with a different type will result in an error.
+You can specify a default value to use in case the environment variable is not set.
+In such a case, the default value is converted to a string using ``str(default)``, unless it is ``null`` (representing Python ``None``) - in which case ``None`` is returned. 
+
 The following example falls back to default passwords when ``DB_PASSWORD`` is not defined:
 
 .. doctest::
 
     >>> cfg = OmegaConf.create(
     ...     {
     ...         "database": {
-    ...             "password1": "${oc.env:DB_PASSWORD,abc123}",
-    ...             "password2": "${oc.env:DB_PASSWORD,'12345'}",
+    ...             "password1": "${oc.env:DB_PASSWORD,password}",
+    ...             "password2": "${oc.env:DB_PASSWORD,12345}",
+    ...             "password3": "${oc.env:DB_PASSWORD,null}",
     ...         },
     ...     }
     ... )
-    >>> cfg.database.password1  # the string 'abc123'
-    'abc123'
-    >>> cfg.database.password2  # the string '12345'
-    '12345'
+    >>> # default is already a string
+    >>> show(cfg.database.password1)
+    type: str, value: 'password'
+    >>> # default is converted to a string automatically
+    >>> show(cfg.database.password2)
+    type: str, value: '12345'
+    >>> # unless it's None
+    >>> show(cfg.database.password3)
+    type: NoneType, value: None
 
 
 Decoding strings with interpolations

omegaconf/omegaconf.py

@@ -98,7 +98,7 @@ def register_default_resolvers() -> None:
     # DEPRECATED: remove in 2.2
     def legacy_env(key: str, default: Optional[str] = None) -> Any:
         warnings.warn(
-            "The `env` resolver is deprecated, see https://github.com/omry/omegaconf/issues/573",
+            "The `env` resolver is deprecated, see https://github.com/omry/omegaconf/issues/573"
         )
 
         try:
@@ -109,22 +109,21 @@ def legacy_env(key: str, default: Optional[str] = None) -> Any:
             else:
                 raise ValidationError(f"Environment variable '{key}' not found")
 
-    def env(key: str, default: Optional[str] = _DEFAULT_MARKER_) -> Optional[str]:
-        if (
-            default is not _DEFAULT_MARKER_
-            and default is not None
-            and not isinstance(default, str)
-        ):
-            raise TypeError(
-                f"The default value of the `oc.env` resolver must be a string or "
-                f"None, but `{default}` is of type {type(default).__name__}"
-            )
-
+    def env(key: str, default: Any = _DEFAULT_MARKER_) -> Optional[str]:
+        """
+        :param key: Environment variable key
+        :param default: Optional default value to use in case the key environment variable is not set.
+                        If default is not a string, it is converted with str(default).
+                        None default is returned as is.
+        :return: The environment variable 'key'. If the environment variable is not set and a default is
+                provided, the default is used. If used, the default is converted to a string with str(default).
+                If the default is None, None is returned (without a string conversion).
+        """
         try:
             return os.environ[key]
         except KeyError:
             if default is not _DEFAULT_MARKER_:
-                return default
+                return str(default) if default is not None else None
             else:
                 raise KeyError(f"Environment variable '{key}' not found")
 

tests/interpolation/built_in_resolvers/test_env.py

@@ -162,19 +162,11 @@ def test_env_default_none(monkeypatch: Any) -> None:
     assert c.my_key is None
 
 
-@mark.parametrize("has_var", [True, False])
-def test_env_non_str_default(monkeypatch: Any, has_var: bool) -> None:
-    if has_var:
-        monkeypatch.setenv("MYKEY", "456")
-    else:
-        monkeypatch.delenv("MYKEY", raising=False)
-
+def test_env_non_str_default(monkeypatch: Any) -> None:
     c = OmegaConf.create({"my_key": "${oc.env:MYKEY, 123}"})
-    with raises(
-        InterpolationResolutionError,
-        match=re.escape(
-            "TypeError raised while resolving interpolation: The default value "
-            "of the `oc.env` resolver must be a string or None, but `123` is of type int"
-        ),
-    ):
-        c.my_key
+
+    monkeypatch.setenv("MYKEY", "456")
+    assert c.my_key == "456"
+
+    monkeypatch.delenv("MYKEY")
+    assert c.my_key == "123"