Use Case: Maps 🗺 with GeoDjango 🌎 PostGIS 🐘 and Leaflet 🍃

Slides from my talk presented on 2019-01-21 at #PyRoma meetup in Rome

For more information:
https://www.paulox.net/talks/#pyroma-meetup-2019

Transcript

1. Maps with GeoDjango PostGIS and Leaflet Paolo Melchiorre & Carmelo Catalfamo Rome - January 21, 2019 Use Case
2. Paolo Melchiorre 2 • Computer Science Engineer • Python Developer ~ 2006 • Django Developer ~ 2011 • Senior Developer @ 20Tab • PostgreSQL user (not DBA) • Remote Worker
3. Carmelo Catalfamo 3 • JavaScript Developer • NodeJS developer ~ 2014 • ReactJS developer ~ 2015 • React Native developer • Frontend developer @ 20tab • Django user
4. Goal 4 • GeoDjango • PostGIS • Leaflet • Use Case • Demo • Conclusion
5. Web mapping 5 • Map delivered by GIS • Static and Dynamic • Interactive and view only • Raster or Vector tiles • Spatial databases • Javascript library
6. GeoDjango 6 • Geographic framework • Spatial Field Types • Spatial ORM queries • GIS geometry interfaces • Admin geometry fields • Many database backends
7. PostGIS 7 • Best GeoDjango backend • PostgreSQL extension • Integrated spatial data • Spatial data types • Spatial indexing • Spatial functions
8. Leaflet 8 • JavaScript library for maps • Open Source • Desktop & Mobile friendly • Light (~38 KB) • Well documented • Simple, preforming, usable
9. Mer et Demeures 1.0 9 • Python 2.7 • Django 1.6 • PostgreSQL 9.3 • Textual Spatial Fields • Leaflet 1.0 • Static/View-only map
10. Mer et Demeures 2.0 10 • Python 3.6 • Django 2.1 / GeoDjango • PostgreSQL 10 • PostGIS 2.4 / Spatial data • Leaflet 1.4 • Dynamic/Interactive map
11. Demo 11 demo.meretdemeures.com
12. Models 12 from django.contrib.gis.db.models import ( MultiPolygonField, PointField) class City(models.Model): # … border = MultiPolygonField() class Ad(models.Model): # … location = PointField()
13. Migrations 13 from django.contrib import postgres from django.db import migrations class Migration(migrations.Migration): dependencies = [('geo', '0001_initial')] operations = [ postgres.operations.CreateExtension( 'postgis' ) ]
14. Managers 14 from django.contrib.gis.geos import Polygon from django.db import models class AdQuerySet(models.QuerySet): def filter_by_bbox(self, bbox): bound_box = Polygon.from_bbox(bbox) return self.filter( location__contained=bound_box )
15. REST API 15 from rest_framework import viewsets from rest_framework_gis import filters class AdViewSet(viewsets.ModelViewSet): # … bbox_filter_field = 'location' filter_backends = [ filters.InBBoxFilter]
16. Admin 16 from django.contrib import gis class AdAdmin(gis.admin.OSMGeoAdmin): # … default_lon = 0 default_lat = 0 default_zoom = 4 map_width = 600 map_height = 400 modifiable = True
17. Ajax/Leaflet JS 17 var map = L.map('map').setView( [lat, lng], zoom ) var tiles = 'https://www.myTiles...' L.tileLayer(tiles).addTo(map) L.marker([51.5, -0.09]).addTo(map)
18. <Container> <Loading visible={loading} /> <Map center={center} zoom={zoom} onMoveend={_ => handleMoveend()}> <Marker coords={[51.5, -0.09]} /> </Map> </Container> React Leaflet JS 18
19. Conclusion 19 • Out-of-the-box features • Spatial & Relational query • Django/PostgreSQL only • Backend clusterization • Administrative levels • Dynamic spatial entity
20. Acknowledgments 20 Mer et Demeures meretdemeures.com 20tab www.20tab.com
21. Resources 21 • postgis.net/docs/manual-2.4 • docs.djangoproject.com/en/2.1/ref/contrib/gis • leafletjs.com/reference-1.4.0.html • github.com/django/django • github.com/postgis/postgis • github.com/leaflet/leaflet
22. Thank you 22 License (CC BY-SA) creativecommons.org/licenses/by-sa/4.0/ Slide speakerdeck.com/pauloxnet
23. Questions 23 gis.stackexchange.com
24. Contacts Paolo Melchiorre @pauloxnet www.paulox.net Carmelo Catalfamo @mratomicbomb_ www.carmelocatalfamo.it