feat: add streaming download functionality for large files in AsyncFiles class

README.md

@@ -532,6 +532,16 @@ result = await async_client.files.download(
 )
 ```
 
+For large async downloads, use `stream_download()` to process bytes as they arrive without buffering the full response in memory:
+
+```python
+async with async_client.files.stream_download(
+    url=await async_client.my_files_home() / "relative_folder/my-file.txt"
+) as result:
+    async for bytes_chunk in result:
+        ...
+```
+
 As a result, you will receive an object of type `FileDownloadResponse`, that you can iterate by byte chunks:
 
 ```python

aidial_client/_http_client/_async.py

@@ -1,5 +1,5 @@
 import asyncio
-from collections.abc import AsyncIterator, Callable, Mapping
+from collections.abc import AsyncIterator, Mapping
 from contextlib import asynccontextmanager, suppress
 from http import HTTPStatus
 from typing import Any
@@ -8,7 +8,7 @@
 
 from aidial_client._auth import AsyncAuthValue, aget_combined_auth_headers
 from aidial_client._exception import DialException
-from aidial_client._http_client._base import BaseHTTPClient
+from aidial_client._http_client._base import BaseHTTPClient, ErrorHandler
 from aidial_client._internal_types._defaults import NOT_GIVEN, NotGiven
 from aidial_client._internal_types._generic import ResponseT
 from aidial_client._internal_types._http_request import FinalRequestOptions
@@ -51,8 +51,7 @@ async def request(
         options: FinalRequestOptions,
         cast_to: type[ResponseT],
         remaining_retries: int | None = None,
-        on_http_error: Callable[[httpx.HTTPStatusError], DialException | None]
-        | None = None,
+        on_http_error: ErrorHandler | None = None,
     ) -> ResponseT:
         retries = self._remaining_retries(remaining_retries, options)
         auth_headers = await self.auth_headers()
@@ -101,16 +100,37 @@ async def request(
                     cast_to=cast_to,
                     remaining_retries=retries,
                 )
-            # Try to get a custom error from response status_code/code/message
-            custom_error = on_http_error(err) if on_http_error else None
-            # or fallback to default processing
-            raised_error = custom_error or self._make_dial_error_from_response(
-                err.response
-            )
-            raise raised_error from err
+            self._raise_for_status(response, on_http_error)
 
         return process_block_response(cast_to=cast_to, response=response)
 
+    @asynccontextmanager
+    async def stream(
+        self,
+        *,
+        options: FinalRequestOptions,
+        on_http_error: ErrorHandler | None = None,
+    ) -> AsyncIterator[httpx.Response]:
+        auth_headers = await self.auth_headers()
+        request = self._build_request(options, auth_headers)
+        try:
+            response = await self._internal_http_client.send(
+                request, stream=True
+            )
+        except httpx.TimeoutException as err:
+            raise DialException(
+                message="Request timed out",
+                status_code=HTTPStatus.REQUEST_TIMEOUT,
+            ) from err
+        except httpx.HTTPError as err:
+            raise DialException(message=f"Request failed: {err}") from err
+
+        try:
+            self._raise_for_status(response, on_http_error)
+            yield response
+        finally:
+            await response.aclose()
+
     @asynccontextmanager
     async def stream_sse(
         self,

aidial_client/_http_client/_base.py

@@ -1,4 +1,5 @@
 from abc import ABC, abstractmethod
+from collections.abc import Callable
 from http import HTTPStatus
 from random import uniform
 from typing import Generic, TypeVar
@@ -16,6 +17,8 @@
     "_HttpInternalClientT", bound=httpx.Client | httpx.AsyncClient
 )
 
+ErrorHandler = Callable[[httpx.HTTPStatusError], DialException | None]
+
 
 class BaseHTTPClient(ABC, Generic[_HttpInternalClientT, AuthValueT]):
     _internal_http_client: _HttpInternalClientT
@@ -106,6 +109,22 @@ def _calculate_retry_sleep_seconds(
         timeout = sleep_seconds + uniform(-0.5, 0.5)  # noqa: S311
         return max(0, timeout)
 
+    def _raise_for_status(
+        self,
+        response: httpx.Response,
+        on_http_error: ErrorHandler | None,
+    ) -> None:
+        try:
+            response.raise_for_status()
+        except httpx.HTTPStatusError as err:
+            # Try to get a custom error from response status_code/code/message
+            custom_error = on_http_error(err) if on_http_error else None
+            # or fallback to default processing
+            raised_error = custom_error or self._make_dial_error_from_response(
+                err.response
+            )
+            raise raised_error from err
+
     def _make_dial_error_from_response(
         self,
         response: httpx.Response,

aidial_client/_http_client/_sync.py

@@ -1,5 +1,5 @@
 import time
-from collections.abc import Callable, Iterator, Mapping
+from collections.abc import Iterator, Mapping
 from contextlib import contextmanager, suppress
 from http import HTTPStatus
 from typing import Any
@@ -8,7 +8,7 @@
 
 from aidial_client._auth import SyncAuthValue, get_combined_auth_headers
 from aidial_client._exception import DialException
-from aidial_client._http_client._base import BaseHTTPClient
+from aidial_client._http_client._base import BaseHTTPClient, ErrorHandler
 from aidial_client._internal_types._defaults import NOT_GIVEN, NotGiven
 from aidial_client._internal_types._generic import ResponseT
 from aidial_client._internal_types._http_request import FinalRequestOptions
@@ -50,8 +50,7 @@ def request(
         cast_to: type[ResponseT],
         options: FinalRequestOptions,
         remaining_retries: int | None = None,
-        on_http_error: Callable[[httpx.HTTPStatusError], DialException | None]
-        | None = None,
+        on_http_error: ErrorHandler | None = None,
     ) -> ResponseT:
         retries = self._remaining_retries(remaining_retries, options)
         auth_headers = self.auth_headers()
@@ -101,13 +100,7 @@ def request(
                     cast_to=cast_to,
                     remaining_retries=retries,
                 )
-            # Try to get a custom error from response status_code/code/message
-            custom_error = on_http_error(err) if on_http_error else None
-            # or fallback to default processing
-            raised_error = custom_error or self._make_dial_error_from_response(
-                err.response
-            )
-            raise raised_error from err
+            self._raise_for_status(response, on_http_error)
 
         return process_block_response(cast_to=cast_to, response=response)
 

aidial_client/helpers/storage_resource.py

@@ -5,6 +5,8 @@
 from aidial_client._compatibility.pydantic_v1 import BaseModel
 from aidial_client._constants import API_PREFIX
 from aidial_client._exception import InvalidDialURLError, NotDialURLError
+from aidial_client._internal_types._http_request import FinalRequestOptions
+from aidial_client._utils._dict import remove_none
 from aidial_client.helpers._url import enforce_trailing_slash
 
 StorageResourceType = Literal["files", "conversations", "prompts"]
@@ -156,3 +158,25 @@ def get_display_name(self, url: str) -> str:
         Get the display name of the resource from the URL
         """
         return self.get_storage_resource(url).bucket_path
+
+    def _prepare_download_request(
+        self,
+        url: str | PurePosixPath,
+        etag_if_match: str | None,
+    ) -> tuple[FinalRequestOptions, str]:
+        storage_resource = self.get_storage_resource(str(url))
+
+        if storage_resource.filename is None:
+            raise InvalidDialURLError("URL points to a directory, not a file")
+
+        options = FinalRequestOptions(
+            method="GET",
+            url=urljoin(API_PREFIX, storage_resource.api_path),
+            headers=remove_none(
+                {
+                    "If-Match": etag_if_match,
+                }
+            ),
+        )
+
+        return options, storage_resource.filename

aidial_client/resources/files.py

@@ -1,3 +1,5 @@
+from collections.abc import AsyncIterator
+from contextlib import asynccontextmanager
 from pathlib import PurePosixPath
 from typing import Literal
 from urllib.parse import urljoin
@@ -8,7 +10,6 @@
 from aidial_client._exception import (
     DialException,
     EtagMismatchError,
-    InvalidDialURLError,
     ResourceNotFoundError,
 )
 from aidial_client._internal_types._generic import NoneType
@@ -70,25 +71,13 @@ def download(
         url: str | PurePosixPath,
         etag_if_match: str | None = None,
     ) -> FileDownloadResponse:
-        storage_resource = self.get_storage_resource(str(url))
-        if storage_resource.filename is None:
-            raise InvalidDialURLError("URL points to a directory, not a file")
+        options, filename = self._prepare_download_request(url, etag_if_match)
         response = self.http_client.request(
             cast_to=httpx.Response,
-            options=FinalRequestOptions(
-                method="GET",
-                url=urljoin(API_PREFIX, storage_resource.api_path),
-                headers=remove_none(
-                    {
-                        "If-Match": etag_if_match,
-                    }
-                ),
-            ),
+            options=options,
             on_http_error=_files_error_processor,
         )
-        return FileDownloadResponse(
-            response=response, filename=storage_resource.filename
-        )
+        return FileDownloadResponse(response=response, filename=filename)
 
     def delete(
         self,
@@ -188,25 +177,26 @@ async def download(
         url: str | PurePosixPath,
         etag_if_match: str | None = None,
     ) -> FileDownloadResponse:
-        storage_resource = self.get_storage_resource(str(url))
-        if storage_resource.filename is None:
-            raise InvalidDialURLError("URL points to a directory, not a file")
+        options, filename = self._prepare_download_request(url, etag_if_match)
         response = await self.http_client.request(
             cast_to=httpx.Response,
-            options=FinalRequestOptions(
-                method="GET",
-                url=urljoin(API_PREFIX, storage_resource.api_path),
-                headers=remove_none(
-                    {
-                        "If-Match": etag_if_match,
-                    }
-                ),
-            ),
+            options=options,
             on_http_error=_files_error_processor,
         )
-        return FileDownloadResponse(
-            response=response, filename=storage_resource.filename
-        )
+        return FileDownloadResponse(response=response, filename=filename)
+
+    @asynccontextmanager
+    async def stream_download(
+        self,
+        url: str | PurePosixPath,
+        etag_if_match: str | None = None,
+    ) -> AsyncIterator[FileDownloadResponse]:
+        options, filename = self._prepare_download_request(url, etag_if_match)
+        async with self.http_client.stream(
+            options=options,
+            on_http_error=_files_error_processor,
+        ) as response:
+            yield FileDownloadResponse(response=response, filename=filename)
 
     async def delete(
         self,

tests/resources/files/test_download.py

@@ -0,0 +1,63 @@
+from typing import Any, cast
+from unittest.mock import AsyncMock
+
+import httpx
+import pytest
+
+from aidial_client._client import AsyncDial
+from aidial_client._exception import InvalidDialURLError
+from tests.client_mock import MockStreamIterator
+
+
+@pytest.mark.asyncio
+async def test_stream_download_async_streams_and_closes_response():
+    captured_requests: list[httpx.Request] = []
+    captured_kwargs: list[dict[str, Any]] = []
+    captured_responses: list[httpx.Response] = []
+    client = AsyncDial(api_key="dummy", base_url="http://dial.core")
+    client._get_my_bucket = cast(Any, AsyncMock(return_value="test-bucket"))
+
+    async def send_mock(
+        request: httpx.Request, *, stream: bool = False, **kwargs: Any
+    ) -> httpx.Response:
+        captured_requests.append(request)
+        captured_kwargs.append({"stream": stream, **kwargs})
+        response = httpx.Response(
+            status_code=200,
+            request=request,
+            stream=MockStreamIterator(mock_chunks=[b"hello ", b"world"]),
+        )
+        captured_responses.append(response)
+        return response
+
+    client._http_client._internal_http_client.send = cast(Any, send_mock)
+
+    async with client.files.stream_download(
+        url=await client.my_files_home() / "folder/file.txt"
+    ) as response:
+        assert response.filename == "file.txt"
+        assert b"".join([chunk async for chunk in response]) == b"hello world"
+
+    assert (
+        captured_requests[0].url.path == "/v1/files/test-bucket/folder/file.txt"
+    )
+    assert captured_kwargs == [{"stream": True}]
+    assert captured_responses[0].is_closed is True
+
+
+@pytest.mark.asyncio
+async def test_stream_download_async_rejects_directory_url():
+    client = AsyncDial(api_key="dummy", base_url="http://dial.core")
+    client._get_my_bucket = cast(Any, AsyncMock(return_value="test-bucket"))
+    send_mock = AsyncMock()
+    client._http_client._internal_http_client.send = cast(Any, send_mock)
+
+    with pytest.raises(
+        InvalidDialURLError, match="URL points to a directory, not a file"
+    ):
+        async with client.files.stream_download(
+            url="files/test-bucket/folder/"
+        ):
+            pass
+
+    send_mock.assert_not_called()