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Reimplemented PostGIS spatial_version with cached_property

This commit is contained in:
Claude Paroz 2013-05-27 11:54:14 +02:00
parent 749c2e4333
commit b14bd60404
1 changed files with 35 additions and 46 deletions
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81
django/contrib/gis/db/backends/postgis/operations.py
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@ -11,6 +11,10 @@ from django.core.exceptions import ImproperlyConfigured
from django.db.backends.postgresql_psycopg2.base import DatabaseOperations
from django.db.utils import DatabaseError
from django.utils import six
from django.utils.functional import cached_property
from .models import GeometryColumns, SpatialRefSys
#### Classes used in constructing PostGIS spatial SQL ####
class PostGISOperator(SpatialOperation):
@ -62,6 +66,7 @@ class PostGISOperations(DatabaseOperations, BaseSpatialOperations):
compiler_module = 'django.contrib.gis.db.models.sql.compiler'
name = 'postgis'
postgis = True
geom_func_prefix = 'ST_'
version_regex = re.compile(r'^(?P<major>\d)\.(?P<minor1>\d)\.(?P<minor2>\d+)')
valid_aggregates = dict([(k, None) for k in
('Collect', 'Extent', 'Extent3D', 'MakeLine', 'Union')])
@ -72,45 +77,7 @@ class PostGISOperations(DatabaseOperations, BaseSpatialOperations):
def __init__(self, connection):
super(PostGISOperations, self).__init__(connection)
# Trying to get the PostGIS version because the function
# signatures will depend on the version used. The cost
# here is a database query to determine the version, which
# can be mitigated by setting `POSTGIS_VERSION` with a 3-tuple
# comprising user-supplied values for the major, minor, and
# subminor revision of PostGIS.
try:
if hasattr(settings, 'POSTGIS_VERSION'):
vtup = settings.POSTGIS_VERSION
if len(vtup) == 3:
# The user-supplied PostGIS version.
version = vtup
else:
# This was the old documented way, but it's stupid to
# include the string.
version = vtup[1:4]
else:
vtup = self.postgis_version_tuple()
version = vtup[1:]
# Getting the prefix -- even though we don't officially support
# PostGIS 1.2 anymore, keeping it anyway in case a prefix change
# for something else is necessary.
if version >= (1, 2, 2):
prefix = 'ST_'
else:
prefix = ''
self.geom_func_prefix = prefix
self.spatial_version = version
except DatabaseError:
raise ImproperlyConfigured(
'Cannot determine PostGIS version for database "%s". '
'GeoDjango requires at least PostGIS version 1.3. '
'Was the database created from a spatial database '
'template?' % self.connection.settings_dict['NAME']
)
# TODO: Raise helpful exceptions as they become known.
prefix = self.geom_func_prefix
# PostGIS-specific operators. The commented descriptions of these
# operators come from Section 7.6 of the PostGIS 1.4 documentation.
self.geometry_operators = {
@ -188,13 +155,13 @@ class PostGISOperations(DatabaseOperations, BaseSpatialOperations):
self.geometry_functions.update(self.distance_functions)
# Only PostGIS versions 1.3.4+ have GeoJSON serialization support.
if version < (1, 3, 4):
if self.spatial_version < (1, 3, 4):
GEOJSON = False
else:
GEOJSON = prefix + 'AsGeoJson'
# ST_ContainsProperly ST_MakeLine, and ST_GeoHash added in 1.4.
if version >= (1, 4, 0):
if self.spatial_version >= (1, 4, 0):
GEOHASH = 'ST_GeoHash'
BOUNDINGCIRCLE = 'ST_MinimumBoundingCircle'
self.geometry_functions['contains_properly'] = PostGISFunction(prefix, 'ContainsProperly')
@ -202,7 +169,7 @@ class PostGISOperations(DatabaseOperations, BaseSpatialOperations):
GEOHASH, BOUNDINGCIRCLE = False, False
# Geography type support added in 1.5.
if version >= (1, 5, 0):
if self.spatial_version >= (1, 5, 0):
self.geography = True
# Only a subset of the operators and functions are available
# for the geography type.
@ -217,7 +184,7 @@ class PostGISOperations(DatabaseOperations, BaseSpatialOperations):
}
# Native geometry type support added in PostGIS 2.0.
if version >= (2, 0, 0):
if self.spatial_version >= (2, 0, 0):
self.geometry = True
# Creating a dictionary lookup of all GIS terms for PostGIS.
@ -260,7 +227,7 @@ class PostGISOperations(DatabaseOperations, BaseSpatialOperations):
self.union = prefix + 'Union'
self.unionagg = prefix + 'Union'
if version >= (2, 0, 0):
if self.spatial_version >= (2, 0, 0):
self.extent3d = prefix + '3DExtent'
self.length3d = prefix + '3DLength'
self.perimeter3d = prefix + '3DPerimeter'
@ -269,6 +236,30 @@ class PostGISOperations(DatabaseOperations, BaseSpatialOperations):
self.length3d = prefix + 'Length3D'
self.perimeter3d = prefix + 'Perimeter3D'
@cached_property
def spatial_version(self):
"""Determine the version of the PostGIS library."""
# Trying to get the PostGIS version because the function
# signatures will depend on the version used. The cost
# here is a database query to determine the version, which
# can be mitigated by setting `POSTGIS_VERSION` with a 3-tuple
# comprising user-supplied values for the major, minor, and
# subminor revision of PostGIS.
if hasattr(settings, 'POSTGIS_VERSION'):
version = settings.POSTGIS_VERSION
else:
try:
vtup = self.postgis_version_tuple()
except DatabaseError:
raise ImproperlyConfigured(
'Cannot determine PostGIS version for database "%s". '
'GeoDjango requires at least PostGIS version 1.3. '
'Was the database created from a spatial database '
'template?' % self.connection.settings_dict['NAME']
)
version = vtup[1:]
return version
def check_aggregate_support(self, aggregate):
"""
Checks if the given aggregate name is supported (that is, if it's
@ -572,9 +563,7 @@ class PostGISOperations(DatabaseOperations, BaseSpatialOperations):
# Routines for getting the OGC-compliant models.
def geometry_columns(self):
from django.contrib.gis.db.backends.postgis.models import GeometryColumns
return GeometryColumns
def spatial_ref_sys(self):
from django.contrib.gis.db.backends.postgis.models import SpatialRefSys
return SpatialRefSys