Use os.PathLike in StaticFiles for directory (#1007)

* Use os.PathLike in StaticFiles for directory

This allows using `pathlib.Path` in addition to `str` for configuring
the base directory of the static files in line with how python3.6+
handles filesystem operations.

Fixes #1004

* Fixed `mimetypes.guess_type` not supporting PathLike on py3.7 and below

* Updated staticfiles documentation with `PathLike` param

docs/staticfiles.md

@@ -5,7 +5,7 @@ Starlette also includes a `StaticFiles` class for serving files in a given direc
 
 Signature: `StaticFiles(directory=None, packages=None, check_dir=True)`
 
-* `directory` - A string denoting a directory path.
+* `directory` - A string or [os.Pathlike][pathlike] denoting a directory path.
 * `packages` - A list of strings of python packages.
 * `html` - Run in HTML mode. Automatically loads `index.html` for directories if such file exist.
 * `check_dir` - Ensure that the directory exists upon instantiation. Defaults to `True`.
@@ -51,3 +51,5 @@ app = Starlette(routes=routes)
 You may prefer to include static files directly inside the "static" directory
 rather than using Python packaging to include static files, but it can be useful
 for bundling up reusable components.
+
+[pathlike]: https://docs.python.org/3/library/os.html#os.PathLike

starlette/responses.py

@@ -4,9 +4,10 @@
 import json
 import os
 import stat
+import sys
 import typing
 from email.utils import formatdate
-from mimetypes import guess_type
+from mimetypes import guess_type as mimetypes_guess_type
 from urllib.parse import quote, quote_plus
 
 from starlette.background import BackgroundTask
@@ -30,6 +31,15 @@
     ujson = None  # type: ignore
 
 
+# Compatibility wrapper for `mimetypes.guess_type` to support `os.PathLike` on <py3.8
+def guess_type(
+    url: typing.Union[str, "os.PathLike[str]"], strict: bool = True
+) -> typing.Tuple[typing.Optional[str], typing.Optional[str]]:
+    if sys.version_info < (3, 8):  # pragma: no cover
+        url = os.fspath(url)
+    return mimetypes_guess_type(url, strict)
+
+
 class Response:
     media_type = None
     charset = "utf-8"
@@ -239,7 +249,7 @@ class FileResponse(Response):
 
     def __init__(
         self,
-        path: str,
+        path: typing.Union[str, "os.PathLike[str]"],
         status_code: int = 200,
         headers: dict = None,
         media_type: str = None,

starlette/staticfiles.py

@@ -15,6 +15,8 @@
 )
 from starlette.types import Receive, Scope, Send
 
+PathLike = typing.Union[str, "os.PathLike[str]"]
+
 
 class NotModifiedResponse(Response):
     NOT_MODIFIED_HEADERS = (
@@ -41,7 +43,7 @@ class StaticFiles:
     def __init__(
         self,
         *,
-        directory: str = None,
+        directory: PathLike = None,
         packages: typing.List[str] = None,
         html: bool = False,
         check_dir: bool = True,
@@ -55,8 +57,8 @@ def __init__(
             raise RuntimeError(f"Directory '{directory}' does not exist")
 
     def get_directories(
-        self, directory: str = None, packages: typing.List[str] = None
-    ) -> typing.List[str]:
+        self, directory: PathLike = None, packages: typing.List[str] = None
+    ) -> typing.List[PathLike]:
         """
         Given `directory` and `packages` arguments, return a list of all the
         directories that should be used for serving static files from.
@@ -71,11 +73,13 @@ def get_directories(
             assert (
                 spec.origin is not None
             ), f"Directory 'statics' in package {package!r} could not be found."
-            directory = os.path.normpath(os.path.join(spec.origin, "..", "statics"))
+            package_directory = os.path.normpath(
+                os.path.join(spec.origin, "..", "statics")
+            )
             assert os.path.isdir(
-                directory
+                package_directory
             ), f"Directory 'statics' in package {package!r} could not be found."
-            directories.append(directory)
+            directories.append(package_directory)
 
         return directories
 
@@ -154,7 +158,7 @@ async def lookup_path(
 
     def file_response(
         self,
-        full_path: str,
+        full_path: PathLike,
         stat_result: os.stat_result,
         scope: Scope,
         status_code: int = 200,

tests/test_staticfiles.py

@@ -1,5 +1,6 @@
 import asyncio
 import os
+import pathlib
 import time
 
 import pytest
@@ -23,6 +24,19 @@ def test_staticfiles(tmpdir):
     assert response.text == "<file content>"
 
 
+def test_staticfiles_with_pathlib(tmpdir):
+    base_dir = pathlib.Path(tmpdir)
+    path = base_dir / "example.txt"
+    with open(path, "w") as file:
+        file.write("<file content>")
+
+    app = StaticFiles(directory=base_dir)
+    client = TestClient(app)
+    response = client.get("/example.txt")
+    assert response.status_code == 200
+    assert response.text == "<file content>"
+
+
 def test_staticfiles_head_with_middleware(tmpdir):
     """
     see https://github.com/encode/starlette/pull/935