fixed render_to_geojson

1 files changed, 235 insertions, 0 deletions

diff --git a/app/projects/shortcuts.py b/app/projects/shortcuts.py
new file mode 100644
index 0000000..d54410c
--- /dev/null
+++ b/app/projects/shortcuts.py
@@ -0,0 +1,235 @@
+from django.contrib.gis.db.models.fields import GeometryField

+#from django.contrib.gis.gdal import Envelope

+from django.contrib.gis.geos import Polygon

+from django.utils import simplejson

+from django.http import HttpResponse

+#from django.db.models.fields.related import ManyRelatedManager

+

+# also need to check out:

+# http://code.google.com/p/dojango/source/browse/trunk/dojango/util/__init__.py#82

+

+

+# example usages:

+

+"""

+

+def a_shapes(request):

+    ids = request.GET.get('ids').split(',')

+    mimetype = 'text/plain' #'application/javascript; charset=utf8'

+    pretty_print = True

+    if ids:

+        qs = WorldBorders.objects.filter(affiliates__in=ids).annotate(num_a=Count('affiliates')).filter(num_a__gt=0)

+    else:

+        qs = WorldBorders.objects.none()

+    return render_to_geojson(qs,

+        extra_attributes=['num_a','affiliates_set'],

+        geom_attribute='point',

+        included_fields=['id','name'],

+        mimetype=mimetype,

+        proj_transform=900913,

+        pretty_print=pretty_print

+        ) 

+    

+def responses(qs,type_='countries',pretty_print=True,mimetype='text/plain'):

+    if type_ == 'locations':

+        qs = qs.geolocations()

+        return render_to_geojson(qs, 

+            excluded_fields=['json'], 

+            geom_field='point',

+            proj_transform=900913,

+            mimetype=mimetype,

+            pretty_print=pretty_print

+            )

+    elif type_ == 'affiliates': 

+        qs = qs.exclude(geokeywords='').attach_locations()

+        return render_to_geojson(qs,

+            included_fields=['id','_geokeywords_cache'], 

+            geom_attribute='point',

+            extra_attributes=['name'],

+            proj_transform=900913,

+            mimetype=mimetype,

+            pretty_print=pretty_print

+            )

+    elif type_ == 'countries':

+        qs2 = W.objects.filter(affiliates__in=qs).annotate(num_a=Count('affiliates')).filter(num_a__gt=0)

+        return render_to_geojson(qs2,

+            extra_attributes=['num_a'],

+            #geom_attribute='point',

+            mimetype=mimetype,

+            pretty_print=pretty_print

+            )                

+    else:# type_ == 'countries' or type is None:

+        if len(qs) > 10:

+            # this is a limit, weird huh?

+            # requires another all() otherwise it 

+            # returns a list!

+            qs = qs.all()[:10]

+        return render_to_geojson(qs,

+            included_fields=['id','_geokeywords_cache'],

+            geom_attribute='countries.unionagg',

+            extra_attributes=['name'],

+            mimetype=mimetype,

+            pretty_print=pretty_print

+            )

+"""

+

+

+

+def render_to_geojson(query_set, geom_field=None, geom_attribute=None, extra_attributes=[],mimetype='text/plain', pretty_print=False, excluded_fields=[],included_fields=[],proj_transform=None):

+    '''

+    

+    Shortcut to render a GeoJson FeatureCollection from a Django QuerySet.

+    Currently computes a bbox and adds a crs member as a sr.org link

+    

+    '''

+    excluded_fields.append('_state')

+    collection = {}

+    if hasattr(query_set,'_meta'): # its a model instance

+        fields = query_set._meta.fields

+        query_set = [query_set]

+    else:

+        fields = query_set.model._meta.fields

+    

+    if geom_attribute:

+        geometry_name = geom_attribute

+        geo_field = None

+        if '.' in geom_attribute:

+            prop, meth = geom_attribute.split('.')

+            if len(query_set):

+                p = getattr(query_set[0],prop)

+                geo_field = getattr(p,meth)

+                if callable(geo_field):

+                    geo_field = geo_field()

+        else:

+            if len(query_set):

+                geo_field = getattr(query_set[0],geom_attribute)

+                if callable(geo_field):

+                    geo_field = geo_field()

+        if not geo_field:

+            srid = 4326

+        else:

+            srid = geo_field.srid

+

+    else:

+        geo_fields = [f for f in fields if isinstance(f, GeometryField)]

+        

+        #attempt to assign geom_field that was passed in

+        if geom_field:

+            #import pdb;pdb.set_trace()

+            geo_fieldnames = [x.name for x in geo_fields]

+            try:

+                geo_field = geo_fields[geo_fieldnames.index(geom_field)]

+            except:

+                raise Exception('%s is not a valid geometry on this model' % geom_field)

+        else:

+            if not len(geo_fields):

+                raise Exception('There appears to be no valid geometry on this model')

+            geo_field = geo_fields[0] # no support yet for multiple geometry fields

+

+            

+        #remove other geom fields from showing up in attributes    

+        if len(geo_fields) > 1:

+            for field in geo_fields:

+                if field.name not in excluded_fields:

+                    excluded_fields.append(field.name)

+

+        geometry_name = geo_field.name

+    

+

+        srid = geo_field.srid

+

+    if proj_transform:

+        to_srid = proj_transform

+    else:

+        to_srid = srid

+    # Gather the projection information

+    crs = {}

+    crs['type'] = "link"

+    crs_properties = {}

+    crs_properties['href'] = 'http://spatialreference.org/ref/epsg/%s/' % to_srid

+    crs_properties['type'] = 'proj4'

+    crs['properties'] = crs_properties 

+    collection['crs'] = crs

+    collection['srid'] = to_srid

+    

+    # Build list of features

+    features = []

+    if query_set.distinct():

+      for item in query_set:

+        feat = {}

+        feat['type'] = 'Feature'

+        if included_fields:

+            d = {}

+            for f in included_fields:

+                if hasattr(item,f):

+                    d[f] = getattr(item,f)

+        else:

+            d = item.__dict__.copy()

+            for field in excluded_fields:

+                    if field in d.keys():

+                        d.pop(field)

+            if geometry_name in d:

+                d.pop(geometry_name)

+

+        for attr in extra_attributes:

+            a = getattr(item,attr)

+            # crappy way of trying to figure out it this is a

+            # m2m, aka 'ManyRelatedManager'

+            if hasattr(a,'values_list'):

+                a = list(a.values_list('id',flat=True))

+            if callable(a):

+                d[attr] = a()

+            else:

+                d[attr] = a

+        if '.' in geometry_name:

+            prop, meth = geometry_name.split('.')

+            a = getattr(item,prop)

+            g = getattr(a,meth)

+            if callable(g):

+                g = g()

+        else:

+            g = getattr(item,geometry_name)

+        if g:

+            if proj_transform:

+                g.transform(proj_transform)

+            feat['geometry'] = simplejson.loads(g.geojson)

+        feat['properties'] = d

+        features.append(feat)

+    else:

+        pass #features.append({'type':'Feature','geometry': {},'properties':{}})

+

+    # Label as FeatureCollection and add Features

+    collection['type'] = "FeatureCollection"    

+    collection['features'] = features

+    

+    # Attach extent of all features

+    if query_set:

+        ex = None

+        query_set.query.distinct = False

+        if hasattr(query_set,'agg_extent'): 

+            ex = [x for x in query_set.agg_extent.tuple]

+        elif '.' in geometry_name:

+            prop, meth = geometry_name.split('.')

+            a = getattr(item,prop)

+            if a:

+                ex = [x for x in a.extent()]

+        else:

+            # make sure qs does not have .distinct() in it...

+            ex = [x for x in query_set.extent()]

+        if ex:

+            if proj_transform:

+                poly = Polygon.from_bbox(ex)

+                poly.srid = srid

+                poly.transform(proj_transform)

+                ex = poly.extent

+        collection['bbox'] = ex

+    

+    # Return response

+    response = HttpResponse()

+    if pretty_print:

+        response.write('%s' % simplejson.dumps(collection, indent=1))

+    else:

+        response.write('%s' % simplejson.dumps(collection))    

+    response['Content-length'] = str(len(response.content))

+    response['Content-Type'] = mimetype

+    return response
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