django-geojson 2.4.0

Serve vectorial map layers with Django

django-geojson is a set of tools to manipulate GeoJSON with Django :

• (De)Serializer for (Geo)Django objects, querysets and lists

• Base views to serve GeoJSON map layers from models

• GeoJSON model and form fields to avoid spatial database backends (compatible with django-leaflet for map widgets)

INSTALL

pip install django-geojson

This package has optional extra dependencies.

If you need GeoJSON fields with map widgets :

pip install "django-geojson [field]"

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

pip install "django-geojson [field,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)

• bbox : Allows you to set your own bounding box on feature collection level

• bbox_auto : True/False (default false). Will automatically generate a bounding box on a per feature level.

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 }};

Model and forms fields

GeoJSON fields are based on Brad Jasper’s JSONField. See INSTALL to install extra dependencies.

They are useful to avoid usual GIS stacks (GEOS, GDAL, PostGIS…) for very simple use-cases (no spatial operation yet).

from .fields import GeoJSONField

class Address(models.Model):
    geom = GeoJSONField()

address = Address()
address.geom = {'type': 'Point', 'coordinates': [0, 0]}
address.save()

Form widgets are rendered with Leaflet maps automatically if django-leaflet is available.

Low-level serializer

from djgeojson.serializers import Serializer as GeoJSONSerializer

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

Low-level deserializer

from djgeojson.serializers import Serializer as GeoJSONSerializer

GeoJSONSerializer().deserialize('geojson', my_geojson)

You can optionally specify the model name directly in the parameters:

GeoJSONSerializer().deserialize('geojson', my_geojson, model_name=my_model_name)

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 :

python manage.py 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

2.4.0 (2014-03-22)

• Add GeoJSON fields

2.3.0 (2014-02-08)

• Python 3 support (thanks @amarandon)

• Add bbox at feature level (thanks @7wonders)

2.2.0 (2013-12-18)

• Deserialization: add ability to specify model name as option (thanks @Vross)

• Deserialization: look-up ìd value in properties whe missing at feature level: (thanks @Vross)

2.1.1 (2013-08-21)

• Set default SRID to 4326 in generic GeoJSON views.

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.