def main(request):
""" Respond to the "/" URL.
This is the main entry point for the tableau_api application.
"""
# Extract our CGI parameters.
location = get_param(request, "location")
if location == None:
return error_response(code=400,
message="Missing 'location' parameter.",
callback=get_param(request, "callback"))
name = get_param(request, "name")
ok = True # initially.
width = get_param(request, "width")
if width == None:
ok = False
else:
try:
width = int(width)
except ValueError:
ok = False
if ok:
if width < 10 or width > 2000:
ok = False
if not ok:
return error_response(code=400,
message="Missing or invalid 'width' parameter.",
callback=get_param(request, "callback"))
ok = True # initially.
height = get_param(request, "height")
if height == None:
ok = False
else:
try:
height = int(height)
except ValueError:
ok = False
if ok:
if height < 10 or height > 2000:
ok = False
if not ok:
return error_response(code=400,
message="Missing or invalid 'height' parameter.",
callback=get_param(request, "callback"))
# See which tableau we need to generate.
tableau = tableauGenerator.select_tableau(location, name)
if tableau == None:
return error_response(code=500, message="No tableau found.",
callback=get_param(request, "callback"))
# See if this tableau already exists in the tableau cache for the requested
# size. If so, we can use the cached JSON data directly.
if tableauCache != None:
json_data = tableauCache.get(tableau.id, width, height)
else:
json_data = None # No cache module -> nothing is cached.
# If we didn't have a cache entry for this tableau and size, we have to
# generate it.
if json_data == None:
try:
generated_tableau = tableauGenerator.generate_tableau(tableau,
width,
height)
except:
# Something went wrong. Print the traceback into the Django log
# and return an error message back to the caller.
traceback.print_exc()
return error_response(code=500, message="Internal server error.",
callback=get_param(request, "callback"))
json_data = json.dumps({'tableau' : generated_tableau})
# If we have a tableau cache, save the generated tableau into the cache
# so that we can retrieve it quickly next time.
if tableauCache != None:
tableauCache.save(tableau.id, width, height, json_data)
# Finally, return the results back to the caller.
callback = get_param(request, "callback")
if callback != None:
json_data = callback + "(" + json_data + ")" # Add JSONP callback.
return HttpResponse(json_data, mimetype="application/json")
def tableau(request):
""" Implement the "/geo/api/location/tableau" API call.
"""
# Extract our CGI parameters.
location = get_param(request, "location")
if location == None:
return error_response(code=400,
message="Missing 'location' parameter.",
callback=get_param(request, "callback"))
name = get_param(request, "name")
ok = True # initially.
width = get_param(request, "width")
if width == None:
ok = False
else:
try:
width = int(width)
except ValueError:
ok = False
if ok:
if width < 10 or width > 2000:
ok = False
if not ok:
return error_response(code=400,
message="Missing or invalid 'width' parameter.",
callback=get_param(request, "callback"))
ok = True # initially.
height = get_param(request, "height")
if height == None:
ok = False
else:
try:
height = int(height)
except ValueError:
ok = False
if ok:
if height < 10 or height > 2000:
ok = False
if not ok:
return error_response(code=400,
message="Missing or invalid 'height' parameter.",
callback=get_param(request, "callback"))
# See which tableau we need to generate.
tableau = tableauGenerator.select_tableau(location, name)
if tableau == None:
return error_response(code=500, message="No tableau found.",
callback=get_param(request, "callback"))
# See if this tableau already exists in the tableau cache for the requested
# size. If so, we use the cached JSON data directly.
try:
cacheEntry = TableauCacheEntry.objects.get(tableau=tableau,
width=width, height=height)
except TableauCacheEntry.DoesNotExist:
cacheEntry = None
if cacheEntry != None:
results = cacheEntry.json_data
# If we didn't have a cache entry for this tableau and size, we have to
# generate it.
if cacheEntry == None:
try:
generated_tableau = tableauGenerator.generate_tableau(tableau,
width,
height)
except:
# Something went wrong. Print the traceback into the Django log
# and return an error message back to the caller.
traceback.print_exc()
return error_response(code=500, message="Internal server error.",
callback=get_param(request, "callback"))
results = json.dumps({'tableau' : generated_tableau})
# Add the generated tableau into the cache so that we can use it next
# time.
# cacheEntry = TableauCacheEntry()
# cacheEntry.tableau = tableau
# cacheEntry.width = width
# cacheEntry.height = height
# cacheEntry.json_data = results
# cacheEntry.save()
# Finally, return the results back to the caller.
callback = get_param(request, "callback")
if callback != None:
results = callback + "(" + results + ")" # Add JSONP callback.
return HttpResponse(results, mimetype="application/json")
