MVT Django view snippet

mvt.py

import os
import shutil
import logging
import psycopg2

from django.conf import settings
from django.shortcuts import render, render_to_response
from django.http import HttpResponse

import mercantile as mc

def _create(z,x,y):
	bounds = mc.bounds(float(x),float(y),float(z))
	xmin = bounds[0]
	ymin = bounds[1]
	xmax = bounds[2]
	ymax = bounds[3]
	tile = None
	
	tilefolder = os.path.join(settings.MVT_CACHEDIR,z,x)
	tilepath = os.path.join(tilefolder,y+'.pbf')
	if not os.path.exists(tilepath):
		logger.info("CACHE MISS")
		conn = psycopg2.connect('dbname=geo24 user=geo password=geo host=localhost')
		cur = conn.cursor()
		
		query = "SELECT ST_AsMVT(q,'comuni',4096,'geom') FROM (SELECT id,nome,ST_AsMVTGeom(geom,ST_Makebox2d(ST_transform(ST_SetSrid(ST_MakePoint(%s,%s),4326),3857),ST_transform(ST_SetSrid(ST_MakePoint(%s,%s),4326),3857)),4096,0,false) AS geom FROM comuni3857) AS q"
		cur.execute(query,(xmin,ymin,xmax,ymax))
		tile = cur.fetchone()[0]
		
		if not os.path.exists(tilefolder):
			os.makedirs(tilefolder)
		
		with open(tilepath, 'wb') as f:
			f.write(tile)
			f.close()

		cur.close()
		conn.close()
	else:
		logger.info("CACHE HIT")
		tile = open(tilepath, 'rb').read()
	
	return tile
	
def view(request):
	return render_to_response('mvt.html',{})

logger = logging.getLogger('django')
def tile(request, z, x, y):
	tile = _create(z, x, y)
	return HttpResponse(tile, content_type='application/octet-stream')