django-geojson 2.1.0

Serve vectorial map layers with Django

django-geojson is a collection of helpers to (de)serialize (Geo)Django objects into GeoJSON.

INSTALL

pip install django-geojson

If you need to load data from GeoJSON files (deserialize), you’ll also need shapely

pip install "django-geojson [shapely]"

USAGE

Add djgeojson to your applications :

# settings.py

INSTALLED_APPS += (
    'djgeojson',
)

(not required for views)

GeoJSON layer view

Very useful for web mapping :

# urls.py
from djgeojson.views import GeoJSONLayerView
...
url(r'^data.geojson$', GeoJSONLayerView.as_view(model=MushroomSpot), name='data'),

Consume the vector layer as usual, for example, with Leaflet loaded in Ajax:

# Leaflet JS
var layer = L.geoJson();
map.addLayer(layer);
$.getJSON("{% url 'data' %}", function (data) {
    layer.addData(data);
});

Inherit generic views only if you need a reusable set of options :

# views.py
from djgeojson.views import GeoJSONLayerView

class MapLayer(GeoJSONLayerView):
    # Options
    precision = 4   # float
    simplify = 0.5  # generalization


# urls.py
from .views import MapLayer, MeetingLayer
...
url(r'^mushrooms.geojson$', MapLayer.as_view(model=MushroomSpot, fields=('name',)), name='mushrooms')

Most common use-cases of reusable options are: low-fi precision, common list of fields between several views, etc.

Options are :

• properties : list of properties names, or dict for mapping field names and properties

• simplify : generalization of geometries (See simplify())

• precision : number of digit after comma

• geometry_field : name of geometry field (default: geom)

• srid : projection (default: 4326, for WGS84)

GeoJSON template filter

Mainly useful to dump features in HTML output and bypass AJAX call :

// Leaflet JS
L.geoJson({{ object_list|geojsonfeature|safe}}).addTo(map);

Will work either for a model, a geometry field or a queryset.

{% load geojson_tags %}

var feature = {{ object|geojsonfeature|safe }};

var geom = {{ object.geom|geojsonfeature|safe }};

var collection = {{ object_list|geojsonfeature|safe }};

Low-level serializer

from djgeojson.serializers import Serializer as GeoJSONSerializer

GeoJSONSerializer().serialize(Restaurants.objects.all(), use_natural_keys=True)

Dump GIS models, or fixtures

Register the serializer in your project :

# settings.py

SERIALIZATION_MODULES = {
    'geojson' : 'djgeojson.serializers'
}

Command-line dumpdata can export files, viewable in GIS software like QGis :

django dumpdata --format=geojson yourapp.Model > export.geojson

Works with loaddata as well, which can now import GeoJSON files.

AUTHORS

• Mathieu Leplatre <[e-mail]>

• Glen Robertson author of django-geojson-tiles at: https://github.com/glenrobertson/django-geojson-tiles/

• @jeffkistler’s author of geojson serializer at: https://gist.github.com/967274

• Ben Welsh and Lukasz Dziedzia for quick test script

Version 1.X:

• Daniel Sokolowski, serializer snippet

• ozzmo, python 2.6 compatibility

LICENSE

• Lesser GNU Public License

CHANGELOG

2.1.0 (2013-08-19)

• Serialize reversed relations using natural keys (fixes #8)

• Support empty geometries (None or NULL in Db)

• Fix serializing property in upper class

2.0.1 (2013-07-10)

• Fix usage of simplify.

• Expose force2d option in view

• Allow to have pk or id in properties if explicitly listed

2.0.0 (2013-07-09)

• Complete rewrite using @jeffkistler and @glenrobertson code

• CRS is added to GeoJSON ouput by default

• Ability to build pk dynamically by passing a lambda

• Ability to provide a bbox

• Ability to use Django natural keys

• Support of ValuesQuerySet

• Support of ForeignKey and ManyToMany

• Added force2d option

** Backwards incompatible changes **

• Geom field is not guessed automatically : Use geometry_field option, default is 'geom'.

• no more pk in properties : use feature id, or list pk in properties explicitly.

• fields list in GeoJSONLayer was renamed properties.

1.2.0 (2013-05-22)

• Shapely is now optional (used for deserialization only)

• Add Django to requirements

• Skip a step in GeoJSON conversion of geometries (fixes #6)

1.1.0 (2013-03-06)

• Django 1.5 support

• Fix template tag geojsonfeature on empty geometries

1.0.0 (2012-08-03)

• Initial working version.