Geodjango OSMGeoAdmin: how can add different layers - django

Question

I noticed that maps in the Geodjango admin have a menu on the right.
How can I add more layers than just one representing the model field the map is related in admin?
This is my model (model.py):
class Foresta(models.Model):
nome = models.CharField("Nome", blank = False, max_length = 255)
descrizione = tinymce_models.HTMLField("Descrizione", blank = True, help_text='Inserire una descrizione del bosco')
slug = models.SlugField("Slug", blank = True)
published = models.BooleanField("Pubblicato")
...
coord = models.PointField("Coordinata punto foresta", blank = False)
# GeoDjango-specific: a geometry field (MultiPolygonField), and
# overriding the default manager with a GeoManager instance.
mpoly = models.MultiPolygonField("Mappa foresta (poligono)", blank = False)
objects = models.GeoManager()
This is my admin model (admin.py):
class ForestaAdmin(admin.OSMGeoAdmin):
default_lon= 1308296
default_lat= 5714101
default_zoom= 9
overlays = ('coord', 'mpoly')
I tried with the 'overlays' option but without success!

Answer 1

You can find the default OSMGeoAdmin settings here. Unfortunately, it doesn't look like you can accomplish this with something as simple as specifying an overlays tuple. Instead, it looks like you should create a custom map template and then override the map_template option in your ForestaAdmin class with the path to your template. Start by copying the default openlayers template and customize the javascript to add your other layers as additional OpenLayers Vector layers.

Answer 2

I had to add extra readonly multipolygon on the map. I redefined osm.html (?just changed osm.js file path cause django used default "gis/admin/osm.js")
{% extends "gis/admin/openlayers.html" %}
{% block openlayers %}{% include "gis/osm.js" %}{% endblock %}
osm.js:
{% extends "gis/admin/osm.js" %}
{% block extra_layers %}
{% if extra_wkt %}
var extraLayer = new OpenLayers.Layer.Vector("extra_layer");
var extraGeometry = new OpenLayers.Feature.Vector(
new OpenLayers.Geometry.fromWKT('{{ extra_wkt }}'),
{}, // attrs
{
fillColor: "#8a8a8a",
fillOpacity: 0.4,
strokeColor: "#000000",
strokeOpacity: 0.6,
strokeWidth: 1,
}
)
extraLayer.addFeatures(extraGeometry);
{{ module }}.map.addLayer(extraLayer);
{% endif %}
{% endblock %}
There is I use extra_wkt value which passed as context.
(mpoly - name of geodjango multipolygon field)
from django.contrib.gis.admin import OSMGeoAdmin, OpenLayersWidget
class OSMLayersWidget(OpenLayersWidget):
def get_context(self, name, value, attrs):
context = super().get_context(name, value, attrs)
if name == "mpoly":
extra_mpoly = MultiPolygon([..., ...])
if extra_mpoly:
srid = self.params['srid']
if extra_mpoly.srid != srid:
try:
extra_mpoly.transform(srid)
extra_wkt = extra_mpoly.wkt
except GDALException as err:
logger.error(
"Error creating geometry from value '%s' (%s)",
extra_mpoly,
err,
)
extra_wkt = ''
else:
extra_wkt = extra_mpoly.wkt
context["extra_wkt"] = extra_wkt
return context
admin.py:
class ServiceZoneAdmin(OSMGeoAdmin):
map_template = 'gis/osm.html'
widget = OSMLayersWidget
Result:

Answer 3

You can use olwidget http://docs.olwidget.org/en/latest/django-olwidget.html. It allows you to edit and show different layers (inside and outside Django admin). However, you might find it difficult to use depending on which Django version are you running.
Finally, I managed to do it as #garnetb said by modifying the openlayers.js file found in (my case) here:
/usr/local/lib/python2.7/dist-packages/django/contrib/gis/templates/gis/admin/openlayers.js
If you can't find it just look for it in the osm.html and/or openlayers.html. So, this is the way I managed to add a second layer. My objective was to add a "visual" only layer, but you can easily modify the controls if you want to edit it. So, let's assume you have a model like this one:
class Lines(gis_models.Model):
name = gis_models.CharField(max_length=10)
geom = gis_models.MultiLineStringField(srid=4326)
geom_points = gis_models.MultiPointField(srid=4326, null=True)
objects = gis_models.GeoManager()
def __unicode__(self):
return self.name
So you see, there are 2 elements being load, the first one are lines and the second one are points. So my objective is to add the lines as a visual reference for when I'm working with the points. To be able to do that, go to openlayers.js and look for the section where the Base Layer is being defined and add something like this.
// Base Layer
{% if field_name != "geom" %}
geom_layer = new OpenLayers.Layer.Vector("visual");
{{ module }}.map.addLayer(geom_layer);
var wkt_vis = document.getElementById('id_geom').value;
if (wkt_vis){
var features = {{ module }}.read_wkt(wkt_vis);
geom_layer.addFeatures(features);
}
else {
alert("no wkt id field");
}
{% endif %}
if ({{ module }}.is_point) {
var style = new OpenLayers.Style({
pointRadius : 4,
strokeColor : 'red',
strokeWidth : 2,
strokeOpacity : 1,
fillColor : 'white',
fillOpacity : 1
});
var layer_style = new OpenLayers.StyleMap({
'default' : style,
});
{{ module }}.layers.vector = new OpenLayers.Layer.Vector(" {{ field_name }}", {styleMap : layer_style});
}
else {
{{ module }}.layers.vector = new OpenLayers.Layer.Vector(" {{ field_name }}");
}
As you can see, the whole idea is that openlayers.js is loaded for every layer, but you can still access other objects. This configuration left me with a handy admin where I'm showing two maps. In the first one, I show the lines and I'm able to modify them. In the second one, I show the lines as a reference and the points are editable. The second part shows you how to set up the points style (just in case...) This is just a simplified example. If you need more details just let me know. I also managed to add a "delete feature" control. I only tried this with GeoDjango base on Django 1.6, but it should work with other versions as far as they use openlayers.js in the same way.