1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
|
"""
Base/mixin classes for the spatial backend database operations and the
`SpatialRefSys` model the backend.
"""
import re
from django.contrib.gis import gdal
from django.utils import six
from django.utils.encoding import python_2_unicode_compatible
class BaseSpatialOperations(object):
"""
This module holds the base `BaseSpatialBackend` object, which is
instantiated by each spatial database backend with the features
it has.
"""
distance_functions = {}
geometry_functions = {}
geometry_operators = {}
geography_operators = {}
geography_functions = {}
gis_terms = {}
truncate_params = {}
# Quick booleans for the type of this spatial backend, and
# an attribute for the spatial database version tuple (if applicable)
postgis = False
spatialite = False
mysql = False
oracle = False
spatial_version = None
# How the geometry column should be selected.
select = None
# Does the spatial database have a geometry or geography type?
geography = False
geometry = False
area = False
centroid = False
difference = False
distance = False
distance_sphere = False
distance_spheroid = False
envelope = False
force_rhr = False
mem_size = False
bounding_circle = False
num_geom = False
num_points = False
perimeter = False
perimeter3d = False
point_on_surface = False
polygonize = False
reverse = False
scale = False
snap_to_grid = False
sym_difference = False
transform = False
translate = False
union = False
# Aggregates
collect = False
extent = False
extent3d = False
make_line = False
unionagg = False
# Serialization
geohash = False
geojson = False
gml = False
kml = False
svg = False
# Constructors
from_text = False
from_wkb = False
# Default conversion functions for aggregates; will be overridden if implemented
# for the spatial backend.
def convert_extent(self, box):
raise NotImplementedError('Aggregate extent not implemented for this spatial backend.')
def convert_extent3d(self, box):
raise NotImplementedError('Aggregate 3D extent not implemented for this spatial backend.')
def convert_geom(self, geom_val, geom_field):
raise NotImplementedError('Aggregate method not implemented for this spatial backend.')
# For quoting column values, rather than columns.
def geo_quote_name(self, name):
return "'%s'" % name
# GeometryField operations
def geo_db_type(self, f):
"""
Returns the database column type for the geometry field on
the spatial backend.
"""
raise NotImplementedError
def get_distance(self, f, value, lookup_type):
"""
Returns the distance parameters for the given geometry field,
lookup value, and lookup type.
"""
raise NotImplementedError('Distance operations not available on this spatial backend.')
def get_geom_placeholder(self, f, value):
"""
Returns the placeholder for the given geometry field with the given
value. Depending on the spatial backend, the placeholder may contain a
stored procedure call to the transformation function of the spatial
backend.
"""
raise NotImplementedError
def get_expression_column(self, evaluator):
"""
Helper method to return the quoted column string from the evaluator
for its expression.
"""
for expr, col_tup in evaluator.cols:
if expr is evaluator.expression:
return '%s.%s' % tuple(map(self.quote_name, col_tup))
raise Exception("Could not find the column for the expression.")
# Spatial SQL Construction
def spatial_aggregate_sql(self, agg):
raise NotImplementedError('Aggregate support not implemented for this spatial backend.')
def spatial_lookup_sql(self, lvalue, lookup_type, value, field):
raise NotImplementedError
# Routines for getting the OGC-compliant models.
def geometry_columns(self):
raise NotImplementedError
def spatial_ref_sys(self):
raise NotImplementedError
@python_2_unicode_compatible
class SpatialRefSysMixin(object):
"""
The SpatialRefSysMixin is a class used by the database-dependent
SpatialRefSys objects to reduce redundnant code.
"""
# For pulling out the spheroid from the spatial reference string. This
# regular expression is used only if the user does not have GDAL installed.
# TODO: Flattening not used in all ellipsoids, could also be a minor axis,
# or 'b' parameter.
spheroid_regex = re.compile(r'.+SPHEROID\[\"(?P<name>.+)\",(?P<major>\d+(\.\d+)?),(?P<flattening>\d{3}\.\d+),')
# For pulling out the units on platforms w/o GDAL installed.
# TODO: Figure out how to pull out angular units of projected coordinate system and
# fix for LOCAL_CS types. GDAL should be highly recommended for performing
# distance queries.
units_regex = re.compile(r'.+UNIT ?\["(?P<unit_name>[\w \'\(\)]+)", ?(?P<unit>[\d\.]+)(,AUTHORITY\["(?P<unit_auth_name>[\w \'\(\)]+)","(?P<unit_auth_val>\d+)"\])?\]([\w ]+)?(,AUTHORITY\["(?P<auth_name>[\w \'\(\)]+)","(?P<auth_val>\d+)"\])?\]$')
@property
def srs(self):
"""
Returns a GDAL SpatialReference object, if GDAL is installed.
"""
if gdal.HAS_GDAL:
# TODO: Is caching really necessary here? Is complexity worth it?
if hasattr(self, '_srs'):
# Returning a clone of the cached SpatialReference object.
return self._srs.clone()
else:
# Attempting to cache a SpatialReference object.
# Trying to get from WKT first.
try:
self._srs = gdal.SpatialReference(self.wkt)
return self.srs
except Exception as msg:
pass
try:
self._srs = gdal.SpatialReference(self.proj4text)
return self.srs
except Exception as msg:
pass
raise Exception('Could not get OSR SpatialReference from WKT: %s\nError:\n%s' % (self.wkt, msg))
else:
raise Exception('GDAL is not installed.')
@property
def ellipsoid(self):
"""
Returns a tuple of the ellipsoid parameters:
(semimajor axis, semiminor axis, and inverse flattening).
"""
if gdal.HAS_GDAL:
return self.srs.ellipsoid
else:
m = self.spheroid_regex.match(self.wkt)
if m: return (float(m.group('major')), float(m.group('flattening')))
else: return None
@property
def name(self):
"Returns the projection name."
return self.srs.name
@property
def spheroid(self):
"Returns the spheroid name for this spatial reference."
return self.srs['spheroid']
@property
def datum(self):
"Returns the datum for this spatial reference."
return self.srs['datum']
@property
def projected(self):
"Is this Spatial Reference projected?"
if gdal.HAS_GDAL:
return self.srs.projected
else:
return self.wkt.startswith('PROJCS')
@property
def local(self):
"Is this Spatial Reference local?"
if gdal.HAS_GDAL:
return self.srs.local
else:
return self.wkt.startswith('LOCAL_CS')
@property
def geographic(self):
"Is this Spatial Reference geographic?"
if gdal.HAS_GDAL:
return self.srs.geographic
else:
return self.wkt.startswith('GEOGCS')
@property
def linear_name(self):
"Returns the linear units name."
if gdal.HAS_GDAL:
return self.srs.linear_name
elif self.geographic:
return None
else:
m = self.units_regex.match(self.wkt)
return m.group('unit_name')
@property
def linear_units(self):
"Returns the linear units."
if gdal.HAS_GDAL:
return self.srs.linear_units
elif self.geographic:
return None
else:
m = self.units_regex.match(self.wkt)
return m.group('unit')
@property
def angular_name(self):
"Returns the name of the angular units."
if gdal.HAS_GDAL:
return self.srs.angular_name
elif self.projected:
return None
else:
m = self.units_regex.match(self.wkt)
return m.group('unit_name')
@property
def angular_units(self):
"Returns the angular units."
if gdal.HAS_GDAL:
return self.srs.angular_units
elif self.projected:
return None
else:
m = self.units_regex.match(self.wkt)
return m.group('unit')
@property
def units(self):
"Returns a tuple of the units and the name."
if self.projected or self.local:
return (self.linear_units, self.linear_name)
elif self.geographic:
return (self.angular_units, self.angular_name)
else:
return (None, None)
@classmethod
def get_units(cls, wkt):
"""
Class method used by GeometryField on initialization to
retrive the units on the given WKT, without having to use
any of the database fields.
"""
if gdal.HAS_GDAL:
return gdal.SpatialReference(wkt).units
else:
m = cls.units_regex.match(wkt)
return m.group('unit'), m.group('unit_name')
@classmethod
def get_spheroid(cls, wkt, string=True):
"""
Class method used by GeometryField on initialization to
retrieve the `SPHEROID[..]` parameters from the given WKT.
"""
if gdal.HAS_GDAL:
srs = gdal.SpatialReference(wkt)
sphere_params = srs.ellipsoid
sphere_name = srs['spheroid']
else:
m = cls.spheroid_regex.match(wkt)
if m:
sphere_params = (float(m.group('major')), float(m.group('flattening')))
sphere_name = m.group('name')
else:
return None
if not string:
return sphere_name, sphere_params
else:
# `string` parameter used to place in format acceptable by PostGIS
if len(sphere_params) == 3:
radius, flattening = sphere_params[0], sphere_params[2]
else:
radius, flattening = sphere_params
return 'SPHEROID["%s",%s,%s]' % (sphere_name, radius, flattening)
def __str__(self):
"""
Returns the string representation. If GDAL is installed,
it will be 'pretty' OGC WKT.
"""
try:
return six.text_type(self.srs)
except:
return six.text_type(self.wkt)
|