Changes between Version 53 and Version 54 of GeoDjango

Timestamp:

Mar 31, 2007, 1:57:18 AM (18 years ago)

Author:

jbronn

Comment:

updated api, fixed some typgraphical errors

GeoDjango

@@ -21 +21 @@
    * [GeoDjango#PostGISOperatorFieldLookupTypes PostGIS Operator Field Lookup Types]
    * [GeoDjango#PostGISGEOSFunctionFieldLookupTypes PostGIS GEOS Function Field Lookup Types]
+   * [GeoDjango#ExtraInstanceMethods Extra Instance Methods]
 
 = Background =
@@ -95 +96 @@
 from django.contrib.gis.db import models
 
-class District(models.Model):
+class District(models.Model, models.GeoMixin):
     name = models.CharField(maxlength=35)
     num  = models.IntegerField()
@@ -102 +103 @@
     objects = models.GeoManager()
 
-class School(models.Model):
+class School(models.Model, models.GeoMixin):
     name  = models.CharField(maxlength=35)
-    point = models.PointField()
+    point = models.PointField(index=True)
 
     objects = models.GeoManager()
 }}}
+
+'''Notes''':  The {{{GeoMixin}}} class allows for [GeoDjango#ExtraInstanceMethods extra instance methods]. The {{{index}}} keyword is used to indicate that a GiST index be created for the School {{{PointField}}}s fields.
 
 Use the {{{manage.py}}} just like you normally would:
@@ -123 +126 @@
 );
 SELECT AddGeometryColumn('geo_app_school', 'point', 4326, 'POINT', 2);
+CREATE INDEX "geo_app_school_point_id" ON "geo_app_school" USING GIST ( "point" GIST_GEOMETRY_OPS );
 SELECT AddGeometryColumn('geo_app_district', 'poly', 4326, 'MULTIPOLYGON', 2);
 COMMIT;
@@ -212 +216 @@
 The following geometry-enabled fields are available:
  * {{{PointField}}}
- * {{{LineStringField}}}  (bug in current version has this as {{{LineString}}}, will be fixed)
+ * {{{LineStringField}}}
  * {{{PolygonField}}}
  * {{{MultiPointField}}}
@@ -224 +228 @@
 from django.contrib.gis.db import models
 
-class Zip(models.Model):
+class Zip(models.Model, models.GeoMixin):
   code = models.IntegerField()
   poly = models.PolygonField(srid=-1, index=True)
+
+  object = models.GeoManager()
 }}}
 
@@ -232 +238 @@
    * Sets the SRID of geometry to the value.  Defaults to 4326 (WGS84)
  * {{{index}}}
-   * If set to True, will create an index for the given geometry.
-   * '''Disabled.'''  Implemented, but there's a bug and won't allow syncdb to execute.
+   * If set to True, will create a GiST index for the given geometry.  Update the index with the PostgreSQL command {{{VACUUM ANALYZE}}} (may take a while to execute depending on how large your geographic-enabled tables are).
 
 == Creating and Saving Models with Geometry Fields ==
@@ -314 +319 @@
    * Requires GEOS
    * Returns 1 (TRUE) if the Geometries are "spatially disjoint".
-   * 
    * PostGIS equivalent {{{Disjoint(geometry, geometry)}}}
  * {{{intersects}}}
@@ -331 +335 @@
    * PostGIS equivelent {{{Relate(geometry, geometry)}}}
 
-
+== Extra Instance Methods ==
+
+A model with geometry fields will get the following methods:
+
+== get_FOO_wkt ==
+
+For every geometry field, the model object will have a {{{get_FOO_wkt}}} method, where {{{FOO}}} is the name of the geometry field.  For example (using the {{{School}}} model from above):
+
+{{{
+>>> skool = School.objects.get(name='PSAS')
+>>> print skool.get_point_wkt()
+POINT(-95.460822 29.745463)
+}}}
+
+== get_FOO_centroid ==
+
+For every geometry field, the model object will have a {{{get_FOO_centroid}}} method, where {{{FOO}}} is the name of the geometry field.  This routine will return the centroid of the geometry.  For example (using the {{{District}}} model from above):
+
+{{{
+>>> dist = District.objects.get(name='Houston ISD')
+>>> print dist.get_poly_centroid()
+POINT(-95.231713 29.723235)
+}}}
+
+== get_FOO_area ==
+
+For every geometry field, the model object will have a {{{get_FOO_area}}} method, where {{{FOO}} is the name of the geometry field.  This routine will return the area of the geometry.
+
+{{{
+>>> dist = District.objects.get(name='Houston ISD')
+>>> print dist.get_poly_area()
+0.08332
+}}}
+
+'''Note''': Units need to be figured out here.