def stream_to_handler(self, request_handler):
"""Write the contents of this file to a
:class:`tornado.web.RequestHandler`. This method calls `flush` on
the RequestHandler, so ensure all headers have already been set.
For a more complete example see the implementation of
:class:`~motor.web.GridFSHandler`.
Takes an optional callback, or returns a Future.
:Parameters:
- `callback`: Optional function taking parameters (self, error)
.. code-block:: python
class FileHandler(tornado.web.RequestHandler):
@tornado.web.asynchronous
@gen.coroutine
def get(self, filename):
db = self.settings['db']
fs = yield motor.MotorGridFS(db()).open()
try:
gridout = yield fs.get_last_version(filename)
except gridfs.NoFile:
raise tornado.web.HTTPError(404)
self.set_header("Content-Type", gridout.content_type)
self.set_header("Content-Length", gridout.length)
yield gridout.stream_to_handler(self)
self.finish()
.. seealso:: Tornado `RequestHandler <http://tornadoweb.org/en/stable/web.html#request-handlers>`_
"""
written = 0
while written < self.length:
# Reading chunk_size at a time minimizes buffering
chunk = yield self.read(self.chunk_size)
# write() simply appends the output to a list; flush() sends it
# over the network and minimizes buffering in the handler.
request_handler.write(chunk)
request_handler.flush()
written += len(chunk)
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