Return JSON data based on GeoDjango Queryset

Question

My code below returns a JSON data based on user's input or query in my HTML page or template. However, I need to modify or do some tweaking with my JSON data in order for me to use it in my datatables plugin. I am using underscore.js to reconstruct the JSON data.

def brgy_info(request):
 if request.method == "GET":
 get_muni = request.GET.get('munisipyo',default='All')
 get_brgy_id = request.GET.get('brgy_id')
 get_bldg_type = request.GET.getlist('bldg_type[]', default='All') 
 reference_high = FloodHazard.objects.filter(hazard='High')
 reference_medium = FloodHazard.objects.filter(hazard='Medium')
 reference_low = FloodHazard.objects.filter(hazard='Low')
 #get all ids based on filter
 ids_high = reference_high.values_list('id', flat=True)
 ids_medium = reference_medium.values_list('id', flat=True)
 ids_low = reference_low.values_list('id', flat=True)
 # create a list
 to_json = []
 args = []
 if get_muni != 'All Municipalities':
 args.append(Q(municipali=get_muni))
 if get_brgy_id not in ["Select Barangay","All Barangay"]:
 args.append(Q(brgy_locat=get_brgy_id))
 if get_bldg_type != 'All': 
 args.append(Q(bldg_type__in=get_bldg_type))
 # this code is results a messy JSON data that need underscore.js to manipulate
 # in order for us to use datatables
 for myid in ids_high:
 getgeom = FloodHazard.objects.get(id=myid).geom
 response_high = list(PolyStructures.objects.filter(geom__within=getgeom, *args).values(
 'bldg_type','bldg_name').annotate(count=Count('bldg_name')))
 for entry in response_high:
 entry['type'] = 'High'
 to_json.append(response_high)
 for myid in ids_medium:
 getgeom = FloodHazard.objects.get(id=myid).geom
 response_medium = list(PolyStructures.objects.filter(geom__within=getgeom, *args).values(
 'bldg_type','bldg_name').annotate(count=Count('bldg_name')))
 for entry in response_medium:
 entry['type'] = 'Medium'
 to_json.append(response_medium)
 for myid in ids_low:
 getgeom = FloodHazard.objects.get(id=myid).geom
 response_low = list(PolyStructures.objects.filter(geom__within=getgeom, *args).values(
 'bldg_type','bldg_name').annotate(count=Count('bldg_name')))
 for entry in response_low:
 entry['type'] = 'Low'
 to_json.append(response_low)
 return HttpResponse(json.dumps(list(to_json)), content_type='application/json')

I find it very taskful for my page, without using underscore.js. This is the snippet of the JSON data result, which is just a sample based on this query:

http://127.0.0.1:8000/cnt_bldg/?brgy_id=Katugasan&munisipyo=Cabadbaran+City

[
 [
 {
 "count": 1,
 "type": "Low",
 "bldg_name": "",
 "bldg_type": ""
 }
 ],
 [
 {
 "count": 1,
 "type": "Low",
 "bldg_name": "Katugasan Multi-Purpose Gym",
 "bldg_type": "Sport Center/Gymnasium/Covered Court"
 },
 {
 "count": 16,
 "type": "Low",
 "bldg_name": "",
 "bldg_type": ""
 },
 {
 "count": 5,
 "type": "Low",
 "bldg_name": "Katugasan Elementary School",
 "bldg_type": "School"
 }
 ],
 [
 {
 "count": 1,
 "type": "Low",
 "bldg_name": "Katugasan Multi-Purpose Gym",
 "bldg_type": "Sport Center/Gymnasium/Covered Court"
 },
 {
 "count": 16,
 "type": "Low",
 "bldg_name": "",
 "bldg_type": ""
 },
 {
 "count": 5,
 "type": "Low",
 "bldg_name": "Katugasan Elementary School",
 "bldg_type": "School"
 }
 ],
 [
 {
 "count": 1,
 "type": "Low",
 "bldg_name": "Katugasan Multi-Purpose Gym",
 "bldg_type": "Sport Center/Gymnasium/Covered Court"
 },
 {
 "count": 16,
 "type": "Low",
 "bldg_name": "",
 "bldg_type": ""
 },
 {
 "count": 5,
 "type": "Low",
 "bldg_name": "Katugasan Elementary School",
 "bldg_type": "School"
 }
 ],
 [
 {
 "count": 3,
 "type": "Low",
 "bldg_name": "",
 "bldg_type": ""
 }
 ]
]

Some values were duplicated, so how do I remove the duplicates? Any ideas to simplify this code for optimization purposes?

• TheCoffeeCup: Hi! Welcome to Code Review. Nice first post; keep it up!

Answer 1

You have a lot of repeated code which does not respect one of the main principle of software engineering : Don't Repeat Yourself (aka DRY).

I might be wrong but I have the feeling that the whole code about hazard being High/Medium/Low can be re-written :

 hazard_levels = ['High', 'Medium', 'Low']
 for hazard_level in hazard_levels:
 reference = FloodHazard.objects.filter(hazard=hazard_level)
 ids = reference.values_list('id', flat=True)
 for myid in ids:
 getgeom = FloodHazard.objects.get(id=myid).geom
 response = list(PolyStructures.objects.filter(geom__within=getgeom, *args).values(
 'bldg_type','bldg_name').annotate(count=Count('bldg_name')))
 for entry in response:
 entry['type'] = hazard_level
 to_json.append(response)

---

Your code does not do anything in the request method is not GET, is this normal ? Should it raise an exception ?

• Sachi Tekina: I will try that. Yes, you are right. I think it is much better if it raise an exception but I just use this function in my Ajax script. In which it returns a bunch of JSON data.