core[minor]: Support multiple keys in get_from_dict_or_env (#23086)

Support passing multiple keys for ge_from_dict_or_env

libs/core/langchain_core/utils/env.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import os
-from typing import Any, Dict, Optional
+from typing import Any, Dict, List, Optional, Union
 
 
 def env_var_is_set(env_var: str) -> bool:
@@ -22,13 +22,37 @@ def env_var_is_set(env_var: str) -> bool:
 
 
 def get_from_dict_or_env(
-    data: Dict[str, Any], key: str, env_key: str, default: Optional[str] = None
+    data: Dict[str, Any],
+    key: Union[str, List[str]],
+    env_key: str,
+    default: Optional[str] = None,
 ) -> str:
-    """Get a value from a dictionary or an environment variable."""
-    if key in data and data[key]:
-        return data[key]
+    """Get a value from a dictionary or an environment variable.
+
+    Args:
+        data: The dictionary to look up the key in.
+        key: The key to look up in the dictionary. This can be a list of keys to try
+            in order.
+        env_key: The environment variable to look up if the key is not
+            in the dictionary.
+        default: The default value to return if the key is not in the dictionary
+            or the environment.
+    """
+    if isinstance(key, (list, tuple)):
+        for k in key:
+            if k in data and data[k]:
+                return data[k]
+
+    if isinstance(key, str):
+        if key in data and data[key]:
+            return data[key]
+
+    if isinstance(key, (list, tuple)):
+        key_for_err = key[0]
     else:
-        return get_from_env(key, env_key, default=default)
+        key_for_err = key
+
+    return get_from_env(key_for_err, env_key, default=default)
 
 
 def get_from_env(key: str, env_key: str, default: Optional[str] = None) -> str:

libs/core/tests/unit_tests/utils/test_env.py

@@ -0,0 +1,64 @@
+import pytest
+
+from langchain_core.utils.env import get_from_dict_or_env
+
+
+def test_get_from_dict_or_env() -> None:
+    assert (
+        get_from_dict_or_env(
+            {
+                "a": "foo",
+            },
+            ["a"],
+            "__SOME_KEY_IN_ENV",
+        )
+        == "foo"
+    )
+
+    assert (
+        get_from_dict_or_env(
+            {
+                "a": "foo",
+            },
+            ["b", "a"],
+            "__SOME_KEY_IN_ENV",
+        )
+        == "foo"
+    )
+
+    assert (
+        get_from_dict_or_env(
+            {
+                "a": "foo",
+            },
+            "a",
+            "__SOME_KEY_IN_ENV",
+        )
+        == "foo"
+    )
+
+    assert (
+        get_from_dict_or_env(
+            {
+                "a": "foo",
+            },
+            "not exists",
+            "__SOME_KEY_IN_ENV",
+            default="default",
+        )
+        == "default"
+    )
+
+    # Not the most obvious behavior, but
+    # this is how it works right now
+    with pytest.raises(ValueError):
+        assert (
+            get_from_dict_or_env(
+                {
+                    "a": "foo",
+                },
+                "not exists",
+                "__SOME_KEY_IN_ENV",
+            )
+            is None
+        )