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