1 """ |
1 """ |
2 The GeometryProxy object, allows for lazy-geometries. The proxy uses |
2 The GeometryProxy object, allows for lazy-geometries. The proxy uses |
3 Python descriptors for instantiating and setting Geometry objects |
3 Python descriptors for instantiating and setting Geometry objects |
4 corresponding to geographic model fields. |
4 corresponding to geographic model fields. |
5 |
5 |
6 Thanks to Robert Coup for providing this functionality (see #4322). |
6 Thanks to Robert Coup for providing this functionality (see #4322). |
7 """ |
7 """ |
8 |
8 |
9 from types import NoneType, StringType, UnicodeType |
9 class GeometryProxy(object): |
10 |
10 def __init__(self, klass, field): |
11 class GeometryProxy(object): |
|
12 def __init__(self, klass, field): |
|
13 """ |
11 """ |
14 Proxy initializes on the given Geometry class (not an instance) and |
12 Proxy initializes on the given Geometry class (not an instance) and |
15 the GeometryField. |
13 the GeometryField. |
16 """ |
14 """ |
17 self._field = field |
15 self._field = field |
18 self._klass = klass |
16 self._klass = klass |
19 |
17 |
20 def __get__(self, obj, type=None): |
18 def __get__(self, obj, type=None): |
21 """ |
19 """ |
22 This accessor retrieves the geometry, initializing it using the geometry |
20 This accessor retrieves the geometry, initializing it using the geometry |
23 class specified during initialization and the HEXEWKB value of the field. |
21 class specified during initialization and the HEXEWKB value of the field. |
24 Currently, only GEOS or OGR geometries are supported. |
22 Currently, only GEOS or OGR geometries are supported. |
25 """ |
23 """ |
|
24 if obj is None: |
|
25 # Accessed on a class, not an instance |
|
26 return self |
|
27 |
26 # Getting the value of the field. |
28 # Getting the value of the field. |
27 geom_value = obj.__dict__[self._field.attname] |
29 geom_value = obj.__dict__[self._field.attname] |
28 |
30 |
29 if isinstance(geom_value, self._klass): |
31 if isinstance(geom_value, self._klass): |
30 geom = geom_value |
32 geom = geom_value |
31 elif (geom_value is None) or (geom_value==''): |
33 elif (geom_value is None) or (geom_value==''): |
32 geom = None |
34 geom = None |
33 else: |
35 else: |
34 # Otherwise, a Geometry object is built using the field's contents, |
36 # Otherwise, a Geometry object is built using the field's contents, |
35 # and the model's corresponding attribute is set. |
37 # and the model's corresponding attribute is set. |
36 geom = self._klass(geom_value) |
38 geom = self._klass(geom_value) |
37 setattr(obj, self._field.attname, geom) |
39 setattr(obj, self._field.attname, geom) |
38 return geom |
40 return geom |
39 |
41 |
40 def __set__(self, obj, value): |
42 def __set__(self, obj, value): |
41 """ |
43 """ |
42 This accessor sets the proxied geometry with the geometry class |
44 This accessor sets the proxied geometry with the geometry class |
43 specified during initialization. Values of None, HEXEWKB, or WKT may |
45 specified during initialization. Values of None, HEXEWKB, or WKT may |
44 be used to set the geometry as well. |
46 be used to set the geometry as well. |
45 """ |
47 """ |
46 # The OGC Geometry type of the field. |
48 # The OGC Geometry type of the field. |
47 gtype = self._field.geom_type |
49 gtype = self._field.geom_type |
48 |
50 |
49 # The geometry type must match that of the field -- unless the |
51 # The geometry type must match that of the field -- unless the |
50 # general GeometryField is used. |
52 # general GeometryField is used. |
51 if isinstance(value, self._klass) and (str(value.geom_type).upper() == gtype or gtype == 'GEOMETRY'): |
53 if isinstance(value, self._klass) and (str(value.geom_type).upper() == gtype or gtype == 'GEOMETRY'): |
52 # Assigning the SRID to the geometry. |
54 # Assigning the SRID to the geometry. |
53 if value.srid is None: value.srid = self._field.srid |
55 if value.srid is None: value.srid = self._field.srid |
54 elif isinstance(value, (NoneType, StringType, UnicodeType)): |
56 elif value is None or isinstance(value, (basestring, buffer)): |
55 # Set with None, WKT, or HEX |
57 # Set with None, WKT, HEX, or WKB |
56 pass |
58 pass |
57 else: |
59 else: |
58 raise TypeError('cannot set %s GeometryProxy with value of type: %s' % (obj.__class__.__name__, type(value))) |
60 raise TypeError('cannot set %s GeometryProxy with value of type: %s' % (obj.__class__.__name__, type(value))) |
59 |
61 |
60 # Setting the objects dictionary with the value, and returning. |
62 # Setting the objects dictionary with the value, and returning. |
61 obj.__dict__[self._field.attname] = value |
63 obj.__dict__[self._field.attname] = value |
62 return value |
64 return value |