From flask to emmett

[josejachuf]

Hello,
I am seeing an example in Flask and uses make_response. I do not really know what he does.

in Flask:

response = make_response(X)
response.headers['Content-Type'] = "application/octet-stream"
return response

In Emmett I made this:

from emmett import response
...
response.headers['Content-Type'] = "application/octet-stream"
return X

It's right?

Best Regards
Jose

[gi0baro]

@josejachuf it depends. Are you trying to serve a file? a stream of binary data?

[josejachuf]

I think both. Specifically it is a vector tile (*.pbf). These are created and cached as files. If the file exists, that file is served, but it is found to the database and cache for later use.

[josejachuf]

tile is bytes type (<class 'bytes'>) In Flask this works fine

tile = get_tile(z, x, y)
response = make_response(tile)
response.headers['Content-Type'] = "application/octet-stream"
return response

in emmett I made this:

tile = get_tile(z, x, y)
response.headers['Content-Type'] = "application/octet-stream" 
return tile

This returns a bytes too, but the maps viewer shows an error and does not render the map

[josejachuf]

It was missing to define the type of output:

output='bytes'

It was resolved

Best regards
Jose

[gi0baro]

@josejachuf sorry for the delay. Defining the output shouldn't be necessary, in fact its design was for performance reasons only. Then probably I should enhance the automatic output recognition.

Anyway, that works, but probably is not what you really want. In case you have an accessible file, then stream_file from emmett.helpers might help you (avoid to load the entire file contents in RAM). You can even use lower APIs, like raising an emmett.http.HTTPIO exception from your route, but without further information about what actually X is in your code, this is the best advice I can give you.

[josejachuf]

Hi @gi0baro, thanks for your answare.
X is a Vector Tile [1], [2]. They are very small files. I am going to serve you from the cache directly with Nginx, without going through Emmett. When they do not exist, Emmett will be created.

[1] https://en.wikipedia.org/wiki/Vector_tiles
[2] https://postgis.net/docs/ST_AsMVT.html