# Copyright 2011-2014 MongoDB, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Utilities for using Motor with Tornado web applications."""
import datetime
import email.utils
import mimetypes
import time
import gridfs
import tornado.web
import motor
from motor.motor_gridfs import _hash_gridout
# mypy: disable-error-code="no-untyped-def,no-untyped-call"
# TODO: this class is not a drop-in replacement for StaticFileHandler.
# StaticFileHandler provides class method make_static_url, which appends
# an checksum of the static file's contents. Templates thus can do
# {{ static_url('image.png') }} and get "/static/image.png?v=1234abcdef",
# which is cached forever. Problem is, it calculates the checksum synchronously.
# Two options: keep a synchronous GridFS available to get each grid file's
# checksum synchronously for every static_url call, or find some other idiom.
class GridFSHandler(tornado.web.RequestHandler):
"""A handler that can serve content from GridFS, very similar to
:class:`tornado.web.StaticFileHandler`.
.. code-block:: python
db = motor.MotorClient().my_database
application = web.Application(
[
(r"/static/(.*)", web.GridFSHandler, {"database": db}),
]
)
By default, requests' If-Modified-Since headers are honored, but no
specific cache-control timeout is sent to clients. Thus each request for
a GridFS file requires a quick check of the file's ``uploadDate`` in
MongoDB. Override :meth:`get_cache_time` in a subclass to customize this.
"""
def initialize(self, database, root_collection="fs"):
self.database = database
self.root_collection = root_collection
def get_gridfs_file(self, bucket, filename, request):
"""Overridable method to choose a GridFS file to serve at a URL.
By default, if a URL pattern like ``"/static/(.*)"`` is mapped to this
``GridFSHandler``, then the trailing portion of the URL is used as the
filename, so a request for "/static/image.png" results in a call to
:meth:`MotorGridFSBucket.open_download_stream_by_name` with "image.png"
as the ``filename`` argument. To customize the mapping of path to
GridFS file, override ``get_gridfs_file`` and return a Future
:class:`~motor.MotorGridOut` from it.
For example, to retrieve the file by ``_id`` instead of filename::
class CustomGridFSHandler(motor.web.GridFSHandler):
def get_gridfs_file(self, bucket, filename, request):
# Path is interpreted as _id instead of name.
# Return a Future MotorGridOut.
return fs.open_download_stream(file_id=ObjectId(path))
:Parameters:
- `bucket`: A :class:`~motor.motor_tornado.MotorGridFSBucket`
- `filename`: A string, the matched group of the URL pattern
- `request`: An :class:`tornado.httputil.HTTPServerRequest`
.. versionchanged:: 1.0
**BREAKING CHANGE**: Now takes a
:class:`~motor.motor_tornado.MotorGridFSBucket`, not a
``MotorGridFS``.
Also takes an additional ``request`` parameter.
.. versionchanged:: 0.2
``get_gridfs_file`` no longer accepts a callback, instead returns
a Future.
"""
return bucket.open_download_stream_by_name(filename)
async def get(self, path, include_body=True):
fs = motor.MotorGridFSBucket(self.database, self.root_collection)
try:
gridout = await self.get_gridfs_file(fs, path, self.request)
except gridfs.NoFile:
raise tornado.web.HTTPError(404) from None
# If-Modified-Since header is only good to the second.
modified = gridout.upload_date.replace(microsecond=0)
self.set_header("Last-Modified", modified)
# Get the hash for the GridFS file.
checksum = _hash_gridout(gridout)
self.set_header("Etag", '"%s"' % checksum)
mime_type = gridout.content_type
# If content type is not defined, try to check it with mimetypes
if mime_type is None:
mime_type, encoding = mimetypes.guess_type(path)
# Starting from here, largely a copy of StaticFileHandler
if mime_type:
self.set_header("Content-Type", mime_type)
cache_time = self.get_cache_time(path, modified, mime_type)
if cache_time > 0:
self.set_header(
"Expires",
datetime.datetime.now(datetime.timezone.utc).replace(tzinfo=None)
+ datetime.timedelta(seconds=cache_time),
)
self.set_header("Cache-Control", "max-age=" + str(cache_time))
else:
self.set_header("Cache-Control", "public")
self.set_extra_headers(path, gridout)
# Check the If-Modified-Since, and don't send the result if the
# content has not been modified
ims_value = self.request.headers.get("If-Modified-Since")
if ims_value is not None:
date_tuple = email.utils.parsedate(ims_value)
# If our MotorClient is tz-aware, assume the naive ims_value is in
# its time zone.
if_since = datetime.datetime.fromtimestamp(time.mktime(date_tuple)).replace(
tzinfo=modified.tzinfo
)
if if_since >= modified:
self.set_status(304)
return
# Same for Etag
etag = self.request.headers.get("If-None-Match")
if etag is not None and etag.strip('"') == checksum:
self.set_status(304)
return
self.set_header("Content-Length", gridout.length)
if include_body:
await gridout.stream_to_handler(self)
# Needed until fix for Tornado bug 751 is released, see
# https://github.com/facebook/tornado/issues/751 and
# https://github.com/facebook/tornado/commit/5491685
self.finish()
def head(self, path):
# get() is a coroutine. Return its Future.
return self.get(path, include_body=False)
def get_cache_time(self, path, modified, mime_type):
"""Override to customize cache control behavior.
Return a positive number of seconds to trigger aggressive caching or 0
to mark resource as cacheable, only. 0 is the default.
"""
return 0
def set_extra_headers(self, path, gridout):
"""For subclass to add extra headers to the response"""