test0908
/
django
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Refactored `get_srid_info` to use the ORM (now possible since it's no longer used in `GeometryField.__init__`), and moved to `fields` module; removed unnecessary code. 

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10493 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Justin Bronn 2009-04-10 18:08:37 +00:00
parent da17a314ca
commit ae7cb577dd
4 changed files with 47 additions and 98 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
django/contrib/gis/db/backend/spatialite/models.py
View File

@ -48,6 +48,11 @@ class SpatialRefSys(models.Model):
ref_sys_name = models.CharField(max_length=256)
proj4text = models.CharField(max_length=2048)
@property
def wkt(self):
from django.contrib.gis.gdal import SpatialReference
return SpatialReference(self.proj4text).wkt
class Meta:
abstract = True
db_table = 'spatial_ref_sys'

72
django/contrib/gis/db/models/fields/__init__.py
View File

@ -4,18 +4,30 @@ from django.contrib.gis.db.backend import SpatialBackend, gqn
# GeometryProxy, GEOS, and Distance imports.
from django.contrib.gis.db.models.proxy import GeometryProxy
from django.contrib.gis.measure import Distance
# The `get_srid_info` function gets SRID information from the spatial
# reference system table w/o using the ORM.
from django.contrib.gis.models import get_srid_info
def deprecated_property(func):
from warnings import warn
warn('This attribute has been deprecated, please use "%s" instead.' % func.__name__[1:])
return property(func)
# Local cache of the spatial_ref_sys table, which holds static data.
# This exists so that we don't have to hit the database each time.
SRID_CACHE = {}
_srid_cache = {}
def get_srid_info(srid):
"""
Returns the units, unit name, and spheroid WKT associated with the
given SRID from the `spatial_ref_sys` (or equivalent) spatial database
table. These results are cached.
"""
global _srid_cache
if SpatialBackend.mysql:
return None, None, None
if not srid in _srid_cache:
from django.contrib.gis.models import SpatialRefSys
sr = SpatialRefSys.objects.get(srid=srid)
units, units_name = sr.units
spheroid = SpatialRefSys.get_spheroid(sr.wkt)
_srid_cache[srid] = (units, units_name, spheroid)
return _srid_cache[srid]
class GeometryField(SpatialBackend.Field):
"The base GIS field -- maps to the OpenGIS Specification Geometry type."
@ -51,9 +63,6 @@ class GeometryField(SpatialBackend.Field):
# easily available in the field instance for distance queries.
self.srid = srid
# units_cache, units_name_cache and _spheroid_cache are lazily loaded.
self._units_cache = self._units_name_cache = self._spheroid_cache = None
# Setting the dimension of the geometry field.
self.dim = dim
@ -63,28 +72,29 @@ class GeometryField(SpatialBackend.Field):
super(GeometryField, self).__init__(**kwargs) # Calling the parent initializtion function
def _populate_srid_info(self):
if self.srid not in SRID_CACHE:
SRID_CACHE[self.srid] = get_srid_info(self.srid)
self._units_cache, self._units_name_cache, self._spheroid_cache = SRID_CACHE[self.srid]
# The following properties are used to get the units, their name, and
# the spheroid corresponding to the SRID of the GeometryField.
def _get_srid_info(self):
# Get attributes from `get_srid_info`.
self._units, self._units_name, self._spheroid = get_srid_info(self.srid)
def _get_units(self):
if self._units_cache is None:
self._populate_srid_info()
return self._units_cache
units = property(_get_units)
@property
def spheroid(self):
if not hasattr(self, '_spheroid'):
self._get_srid_info()
return self._spheroid
def _get_units_name(self):
if self._units_name_cache is None:
self._populate_srid_info()
return self._units_name_cache
units_name = property(_get_units_name)
@property
def units(self):
if not hasattr(self, '_units'):
self._get_srid_info()
return self._units
def _get_spheroid(self):
if self._spheroid_cache is None:
self._populate_srid_info()
return self._spheroid_cache
_spheroid = property(_get_spheroid)
@property
def units_name(self):
if not hasattr(self, '_units_name'):
self._get_srid_info()
return self._units_name
# The following properties are for formerly private variables that are now
# public for GeometryField. Because of their use by third-party applications,

3
django/contrib/gis/db/models/query.py
View File

@ -4,10 +4,9 @@ from django.db.models.query import QuerySet, Q, ValuesQuerySet, ValuesListQueryS
from django.contrib.gis.db.backend import SpatialBackend
from django.contrib.gis.db.models import aggregates
from django.contrib.gis.db.models.fields import GeometryField, PointField
from django.contrib.gis.db.models.fields import get_srid_info, GeometryField, PointField
from django.contrib.gis.db.models.sql import AreaField, DistanceField, GeomField, GeoQuery, GeoWhereNode
from django.contrib.gis.measure import Area, Distance
from django.contrib.gis.models import get_srid_info
class GeoQuerySet(QuerySet):
"The Geographic QuerySet."

65
django/contrib/gis/models.py
View File

@ -214,14 +214,6 @@ class SpatialRefSysMixin(object):
except:
return unicode(self.wkt)
# Defining dummy default first; if spatial db, will overrride.
def get_srid_info(srid):
"""
Dummy routine for the backends that do not have the OGC required
spatial metadata tables (like MySQL).
"""
return None, None, None
# Django test suite on 2.3 platforms will choke on code inside this
# conditional.
if not PYTHON23:
@ -237,62 +229,5 @@ if not PYTHON23:
class SpatialRefSys(SpatialBackend.SpatialRefSys, SpatialRefSysMixin):
pass
GeometryColumns = SpatialBackend.GeometryColumns
# Override `get_srid_info` with something real thing.
def get_srid_info(srid):
"""
Returns the units, unit name, and spheroid WKT associated with the
given SRID from the `spatial_ref_sys` (or equivalent) spatial database
table. We use a database cursor to execute the query because this
function is used when it is not possible to use the ORM (for example,
during field initialization).
"""
# SRID=-1 is a common convention for indicating the geometry has no
# spatial reference information associated with it. Thus, we will
# return all None values without raising an exception.
if srid == -1: return None, None, None
# Getting the spatial reference WKT associated with the SRID from the
# `spatial_ref_sys` (or equivalent) spatial database table. This query
# cannot be executed using the ORM because this information is needed
# when the ORM cannot be used (e.g., during the initialization of
# `GeometryField`).
from django.db import connection
cur = connection.cursor()
qn = connection.ops.quote_name
stmt = 'SELECT %(table)s.%(wkt_col)s FROM %(table)s WHERE (%(table)s.%(srid_col)s = %(srid)s)'
params = {'table' : qn(SpatialRefSys._meta.db_table),
'srid_col' : qn('srid'),
'srid' : srid,
}
if SpatialBackend.spatialite:
if not HAS_GDAL: raise Exception('GDAL is required to use the SpatiaLite backend.')
params['wkt_col'] = 'proj4text'
else:
params['wkt_col'] = qn(SpatialRefSys.wkt_col())
# Executing the SQL statement.
cur.execute(stmt % params)
# Fetching the WKT from the cursor; if the query failed raise an Exception.
fetched = cur.fetchone()
if not fetched:
raise ValueError('Failed to find spatial reference entry in "%s" corresponding to SRID=%s.' %
(SpatialRefSys._meta.db_table, srid))
if SpatialBackend.spatialite:
# Because the `spatial_ref_sys` table does _not_ contain a WKT column,
# we have to use GDAL to determine the units from the PROJ.4 string.
srs_wkt = SpatialReference(fetched[0]).wkt
else:
srs_wkt = fetched[0]
connection.close()
# Getting metadata associated with the spatial reference system identifier.
# Specifically, getting the unit information and spheroid information
# (both required for distance queries).
unit, unit_name = SpatialRefSys.get_units(srs_wkt)
spheroid = SpatialRefSys.get_spheroid(srs_wkt)
return unit, unit_name, spheroid
except:
pass