Hackernoon logoHow To Build Location-Based App with Geo🌎Django by@lyama

How To Build Location-Based App with Geo🌎Django

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@lyamalymaa

Top Secret ......

GeoDjango is a built-in application that is included as a contrib module in Django. It’s actually a complete framework itself that can also be used separately from Django. It provides a toolbox of utilities for building GIS web applications.

Purpose of this tutorial

Nothing much fancy, here we are getting co-ordinates(Longitude, Latitude) of location by inputting names of country and city.

Requirements :

Note: above requirements need to be installed on your machine separately before continuing

Project setup:

$ mkdir dj_gis && cd dj_gis
$ python3 -m venv env
$ source env/bin/activate
$ pip install django djangorestframework django-leaflet geopy psycopg2-binary 
$ django-admin.py startproject config
$ python manage.py startapp location

config/settings.py

#config/settings.py

INSTALLED_APPS = [
    "django.contrib.gis",
    "location",
    "rest_framework",
]

config/urls.py

#config/urls.py

from django.contrib import admin
from django.urls import path
from django.urls.conf import include


urlpatterns = [
    path("admin/", admin.site.urls),
    path("api/v1/", include("location.urls")),
]

include url.py file on location app

#location/urls.py

from django.urls import path

urlpatterns = []

So we finished basic setups

Let's create a model location/models.py

from django.db import models
from django.contrib.gis.db import models # GeoDjango Model API


class Hotel(models.Model):
    name = models.CharField(max_length=255)
    address = models.CharField(max_length=255)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    location = models.PointField(null=True) # Spatial Field Types

    def __str__(self) -> str:
        return self.name

here, we include a pointfield spatial field of geo django model api.

let's create a serializer and views for our model.

# location/serializers.py

from location.models import Hotel
from rest_framework import serializers


class HotelSerializer(serializers.ModelSerializer):
    class Meta:
        model = Hotel

        fields = ("id", "name", "address", "location")

        extra_kwargs = {"location": {"read_only": True}}

location/views.py

from rest_framework import generics
from .models import Hotel

from django.contrib.gis.geos import Point
from geopy.geocoders import Nominatim

geolocator = Nominatim(user_agent="location")


class ListCreateGenericViews(generics.ListCreateAPIView):
    queryset = Hotel.objects.all()
    serializer_class = HotelSerializer

    def perform_create(self, serializer):
        address = serializer.initial_data["address"]
        g = geolocator.geocode(address)
        lat = g.latitude
        lng = g.longitude
        pnt = Point(lng, lat)
        print(pnt)
        serializer.save(location=pnt)


class HotelUpdateRetreiveView(generics.RetrieveUpdateDestroyAPIView):
    queryset = Hotel.objects.all()
    serializer_class = HotelSerializer

    def perform_update(self, serializer):
        address = serializer.initial_data["address"]
        g = geolocator.geocode(address)
        lat = g.latitude
        lng = g.longitude
        pnt = Point(lng, lat)
        print(pnt)
        serializer.save(location=pnt)

Note: above view can be further refactor using viewsets or your desired ones.

so, geopy library comes in handy, which is is a Python client for several popular geocoding web services. geopy makes it easy for Python developers to locate the coordinates of addresses, cities, countries, and landmarks across the globe using third-party geocoders and other data sources.

let's update our urls:

#location/urls.py

from django.urls import path
from .views import HotelUpdateRetreiveView, ListCreateGenericViews

urlpatterns = [
    path("hotels", ListCreateGenericViews.as_view()),
    path(
        "hotels/<str:pk>",
        HotelUpdateRetreiveView.as_view(),
    ),
]

Creating a Database:

sudo -u postgres psql

CREATE DATABASE locator;

CREATE USER locator WITH PASSWORD 'locator';

CREATE EXTENSION postgis;

ALTER ROLE locator SET client_encoding TO 'utf8';

ALTER ROLE locator SET default_transaction_isolation TO 'read committed';

ALTER ROLE locator SET timezone TO 'UTC';

ALTER ROLE locator SUPERUSER;

GRANT ALL PRIVILEGES ON DATABASE locator TO locator;

let's make some changes on our settings.py

INSTALLED_APPS = [
    "django.contrib.admin",
    "django.contrib.auth",
    "django.contrib.contenttypes",
    "django.contrib.sessions",
    "django.contrib.messages",
    "django.contrib.staticfiles",
    "django.contrib.gis",
    "location",
    "rest_framework",
    "leaflet",
]

DATABASES = {
    "default": {
        "ENGINE": "django.contrib.gis.db.backends.postgis",
        "NAME": "locator",
        "USER": "locator",
        "PASSWORD": "locator",
        "HOST": "localhost",
        "PORT": "5432",
    }
}

LEAFLET_CONFIG = {
    # "SPATIAL_EXTENT": (5.0, 44.0, 7.5, 46),
    "DEFAULT_CENTER": (13.3888599 52.5170365), #set your corordinate
    "DEFAULT_ZOOM": 16,
    "MIN_ZOOM": 3,
    "MAX_ZOOM": 20,
    "DEFAULT_PRECISION": 6,
    "SCALE": "both",
    "ATTRIBUTION_PREFIX": "powered by me",
}

Registering model on admin

from django.contrib import admin
from leaflet.admin import LeafletGeoAdmin

from .models import Hotel


@admin.register(Hotel)
class HotelAdmin(LeafletGeoAdmin):
    list_display = ("id", "name", "address", "location", "created_at", "updated_at")
so, we have added leaflet, leaflet_config and database. For more about Leaflet you can visit Read the docs

let's run our app:

python manage.py makemigrations
python manage.py migrate
python manage.py createsuperuser
python manage.py runserver

here, what you get on the admin panel.

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Let's add some data using browsable api or you can use postman too.

Try it out yourself for update and delete

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You can find the code in github repo.

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