Display on a map objects matching a queryset with Django

Question

I have a Django app, where each user can add a product with multiple possible metrics (width, height and length combination). A user must also specify in which city this product is located. Users can also search within the database all products matching specific metrics. I use Django 1.11 and am seaching for a solution to display on an interactive map all the products matching a queryset.

I am trying to do it with django-leaflet and django-geojson (as my db is not gis-oriented and I don't need heavy geo-computations), but I am facing some difficulties because my "PointField" is not in my product Model but in the Location Model and on the map I need to display Product properties, so I must serialize all these data together.

If you prefer code rather than words, here is a simplified version of my relevant files.

#models.py

class Product(models.Model):
    name = models.CharField()
    owner = models.ForeignKey(User)
    photo = models.ImageField(...)
    dimensions = models.ManyToManyField(Metrics)
    location = models.ForeignKey(Location, related_name='products', related_query_name='product')

class Metrics(models.Model):
   width = models.PositiveIntegerField()
   height = models.PositiveIntegerField()
   length = models.PositiveIntegerField()

class Location(models.Model):
   zip_code = models.PositiveIntegerField()
   city_name = models.CharField()
   slug = models.SlugField(max_length=500, blank=True)
   geom = PointField(default={'type': 'Point', 'coordinates': [0, 0]})


#views.py

class SearchResultListView(ListView):
     model = models.Product
     template_name='my_app/searchresult_list.html'
     context_object_name = 'product_list'

     def get_context_data(self, **kwargs):
         context = super().get_context_data(**kwargs)
         query_width = self.request.GET['width']
         query_height = self.request.GET['height']
         query_length = self.request.GET['length']
         context['product_list'] = context['product_list'].filter(metrics__width=query_width, 
         metrics__length=query_length, metrics__height=query_height)
         return context

#urls.py

????

#template.html

????

I saw in the django-geojson documentation multiple ways to hit the db (GeoJSON layer view, Tiled GeoJSON layer view, GeoJSON template filter, low-level serialization). But I struggle to find the way to match my needs as my properties are in the Product Model, my coordinates are in the Location Model and my queryset in a non-related class-based view.

Any idea on the best way to perform my task? Should I continue with django-geojson or are there better apps for my purpose?

Mark Bailey · Accepted Answer · 2019-12-18 16:41:35Z

0

Your Product and Location look OK, but it is not clear what you are trying to do with Metrics. To select products near some place you want something like:

queryset = Product.objects.filter(location__geom__distance_lt=(someLocation, D(m=50)))

https://docs.djangoproject.com/en/3.0/ref/contrib/gis/geoquerysets/#distance-lt

answered Dec 18, 2019 at 16:41

Mark Bailey

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2 Comments

ThOmOrOw Over a year ago

Metrics are just characteristics of my Product. A product can have multiple Metrics, thus there is a ManytoMany field that binds Product and Metrics. My question is about how to render on a map the location (and product details) of all the products matching the queryset as defined in my views.py.

context['product_list'] = context['product_list'].filter(metrics__width=query_width,           metrics__length=query_length, metrics__height=query_height)

ThOmOrOw Over a year ago

In other words, let's consider that I have my desired product queryset: queryset = Product.objects.filter(....some filter...) I guess I will have to serialize in geojson this queryset (without using gis methods because I don't have a gis-db) to pass it to JS code in my template.

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