Recipe for returning a file as response to a request

[Curtis]

I'm trying to use Aspen for some quick and dirty impedance matching between some static content and a service that is sending HTTP requests with a peculiar format.

I want to receive a request of the form "foo?x=1&y=2&z=3", pick out a file in the filesystem based on that (e.g. "1/2/3.png") and then return that as the response to the request.

Is there a recipe for loading a file and returning the contents plus mime type as the response in a simplate? I started poking through the source to see how Aspen processes requests to return static files, but then I thought I would just be lazy and ask.

Thanks,
--Curtis

[Chad Whitacre]

Curtis,

So /foo is an aspen endpoint that takes a querystring? An aspen endpoint without its own file extension is going to act as a Negotiated Simplate:

    http://aspen.io/simplates/negotiated/

Here's an untested simplate example:

--------BEGIN--------

import mimetypes

^L

filepath = '/'.join([qs['x'], qs['y'], qs['z']])

response.body = open(filepath).read()

response.headers['Content-Type'] = mimetypes.guess(filepath)

^L text/plain

--------END--------

Does that point in the right direction?

IIRC, you might even be able to skip the read and set response.body to a file-like object directly.

Since it's a negotiated simplate (and not a rendered simplate) I'm pretty sure you need the "text/plain" so-called "specline" for the so-called "content page".

chad

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[Curtis Galloway]

Close, but not quite:

--------BEGIN--------

import mimetypes, os

^L

dirname = os.path.dirname(request.fs)

filepath = os.path.join(dirname, '/'.join([qs['x'], qs['y'], qs['z']]))

response.body = open(filepath, 'rb').read()

response.headers['Content-Type'] = mimetypes.guess_type(filepath)[0]

^L text/plain

--------END--------

...except that even though it's returning the contents of the file in the body of the response, the client doesn't get the data.  Hmmm.

--Curtis

[Chad Whitacre]

Curtis,

Ah, right, sorry. What's happening is that the text/plain content page is clobbering the response.body that you set.

Option 1: raise response, like this:

...

response.body = foo

response.headers['Foo'] = 'bar'

raise response

^L text/plain

Option 2: use the content page, like this:

...

response.headers['Foo'] = 'bar'

^L text/plain

{{ open(filepath, 'rb').read()

Again, that's untested. Option 2 will be more performant at scale (raising is an order of magnitude slower than not), though I'm not entirely sure how option 2 will behave with the mismatch in content types. Option 1 should do the trick if option 2 doesn't work and performance isn't a driving concern.

Also, I would not expect request.fs to point to a directory. Are you sure that's right?

Lastly, you can drop to pdb inside simplates, to aid debugging. Throw this any ol' place in page 2 of your simplate:

import pdb; pdb.set_trace()

chad