330 lines
13 KiB
Python
330 lines
13 KiB
Python
import re
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from decimal import Decimal
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from django.contrib.gis.db.backends.base import BaseSpatialOperations
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from django.contrib.gis.db.backends.util import SpatialOperation, SpatialFunction
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from django.contrib.gis.db.backends.spatialite.adapter import SpatiaLiteAdapter
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from django.contrib.gis.geometry.backend import Geometry
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from django.contrib.gis.measure import Distance
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from django.core.exceptions import ImproperlyConfigured
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from django.db.backends.sqlite3.base import DatabaseOperations
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class SpatiaLiteOperator(SpatialOperation):
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"For SpatiaLite operators (e.g. `&&`, `~`)."
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def __init__(self, operator):
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super(SpatiaLiteOperator, self).__init__(operator=operator)
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class SpatiaLiteFunction(SpatialFunction):
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"For SpatiaLite function calls."
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def __init__(self, function, **kwargs):
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super(SpatiaLiteFunction, self).__init__(function, **kwargs)
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class SpatiaLiteFunctionParam(SpatiaLiteFunction):
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"For SpatiaLite functions that take another parameter."
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sql_template = '%(function)s(%(geo_col)s, %(geometry)s, %%s)'
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class SpatiaLiteDistance(SpatiaLiteFunction):
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"For SpatiaLite distance operations."
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dist_func = 'Distance'
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sql_template = '%(function)s(%(geo_col)s, %(geometry)s) %(operator)s %%s'
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def __init__(self, operator):
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super(SpatiaLiteDistance, self).__init__(self.dist_func,
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operator=operator)
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class SpatiaLiteRelate(SpatiaLiteFunctionParam):
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"For SpatiaLite Relate(<geom>, <pattern>) calls."
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pattern_regex = re.compile(r'^[012TF\*]{9}$')
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def __init__(self, pattern):
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if not self.pattern_regex.match(pattern):
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raise ValueError('Invalid intersection matrix pattern "%s".' % pattern)
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super(SpatiaLiteRelate, self).__init__('Relate')
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# Valid distance types and substitutions
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dtypes = (Decimal, Distance, float, int, long)
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def get_dist_ops(operator):
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"Returns operations for regular distances; spherical distances are not currently supported."
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return (SpatiaLiteDistance(operator),)
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class SpatiaLiteOperations(DatabaseOperations, BaseSpatialOperations):
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compiler_module = 'django.contrib.gis.db.models.sql.compiler'
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name = 'spatialite'
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spatialite = True
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version_regex = re.compile(r'^(?P<major>\d)\.(?P<minor1>\d)\.(?P<minor2>\d+)')
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valid_aggregates = dict([(k, None) for k in
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('Extent', 'Union')])
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Adapter = SpatiaLiteAdapter
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area = 'Area'
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centroid = 'Centroid'
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contained = 'MbrWithin'
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difference = 'Difference'
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distance = 'Distance'
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envelope = 'Envelope'
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intersection = 'Intersection'
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length = 'GLength' # OpenGis defines Length, but this conflicts with an SQLite reserved keyword
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num_geom = 'NumGeometries'
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num_points = 'NumPoints'
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point_on_surface = 'PointOnSurface'
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scale = 'ScaleCoords'
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svg = 'AsSVG'
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sym_difference = 'SymDifference'
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transform = 'Transform'
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translate = 'ShiftCoords'
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union = 'GUnion' # OpenGis defines Union, but this conflicts with an SQLite reserved keyword
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unionagg = 'GUnion'
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from_text = 'GeomFromText'
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from_wkb = 'GeomFromWKB'
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select = 'AsText(%s)'
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geometry_functions = {
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'equals' : SpatiaLiteFunction('Equals'),
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'disjoint' : SpatiaLiteFunction('Disjoint'),
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'touches' : SpatiaLiteFunction('Touches'),
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'crosses' : SpatiaLiteFunction('Crosses'),
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'within' : SpatiaLiteFunction('Within'),
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'overlaps' : SpatiaLiteFunction('Overlaps'),
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'contains' : SpatiaLiteFunction('Contains'),
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'intersects' : SpatiaLiteFunction('Intersects'),
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'relate' : (SpatiaLiteRelate, basestring),
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# Retruns true if B's bounding box completely contains A's bounding box.
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'contained' : SpatiaLiteFunction('MbrWithin'),
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# Returns true if A's bounding box completely contains B's bounding box.
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'bbcontains' : SpatiaLiteFunction('MbrContains'),
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# Returns true if A's bounding box overlaps B's bounding box.
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'bboverlaps' : SpatiaLiteFunction('MbrOverlaps'),
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# These are implemented here as synonyms for Equals
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'same_as' : SpatiaLiteFunction('Equals'),
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'exact' : SpatiaLiteFunction('Equals'),
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}
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distance_functions = {
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'distance_gt' : (get_dist_ops('>'), dtypes),
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'distance_gte' : (get_dist_ops('>='), dtypes),
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'distance_lt' : (get_dist_ops('<'), dtypes),
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'distance_lte' : (get_dist_ops('<='), dtypes),
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}
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geometry_functions.update(distance_functions)
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def __init__(self, connection):
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super(DatabaseOperations, self).__init__()
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self.connection = connection
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# Load the spatialite library (must be done before getting the
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# SpatiaLite version).
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self.connection.load_spatialite()
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try:
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vtup = self.spatialite_version_tuple()
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version = vtup[1:]
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if version < (2, 3, 1):
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raise ImproperlyConfigured('GeoDjango only supports SpatiaLite versions '
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'2.3.1 and above')
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self.spatial_version = version
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except ImproperlyConfigured:
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raise
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except Exception, msg:
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raise ImproperlyConfigured('Cannot determine the SpatiaLite version for the "%s" '
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'database (error was "%s"). Was the SpatiaLite initialization '
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'SQL loaded on this database?' %
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(self.connection.settings_dict['NAME'], msg))
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# Creating the GIS terms dictionary.
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gis_terms = ['isnull']
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gis_terms += self.geometry_functions.keys()
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self.gis_terms = dict([(term, None) for term in gis_terms])
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def check_aggregate_support(self, aggregate):
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"""
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Checks if the given aggregate name is supported (that is, if it's
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in `self.valid_aggregates`).
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"""
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agg_name = aggregate.__class__.__name__
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return agg_name in self.valid_aggregates
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def convert_geom(self, wkt, geo_field):
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"""
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Converts geometry WKT returned from a SpatiaLite aggregate.
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"""
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if wkt:
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return Geometry(wkt, geo_field.srid)
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else:
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return None
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def geo_db_type(self, f):
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"""
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Returns None because geometry columnas are added via the
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`AddGeometryColumn` stored procedure on SpatiaLite.
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"""
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return None
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def get_distance(self, f, value, lookup_type):
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"""
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Returns the distance parameters for the given geometry field,
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lookup value, and lookup type. SpatiaLite only supports regular
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cartesian-based queries (no spheroid/sphere calculations for point
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geometries like PostGIS).
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"""
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if not value:
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return []
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value = value[0]
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if isinstance(value, Distance):
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if f.geodetic(self.connection):
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raise ValueError('SpatiaLite does not support distance queries on '
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'geometry fields with a geodetic coordinate system. '
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'Distance objects; use a numeric value of your '
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'distance in degrees instead.')
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else:
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dist_param = getattr(value, Distance.unit_attname(f.units_name(self.connection)))
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else:
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dist_param = value
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return [dist_param]
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def get_geom_placeholder(self, f, value):
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"""
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Provides a proper substitution value for Geometries that are not in the
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SRID of the field. Specifically, this routine will substitute in the
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Transform() and GeomFromText() function call(s).
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"""
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def transform_value(value, srid):
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return not (value is None or value.srid == srid)
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if hasattr(value, 'expression'):
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if transform_value(value, f.srid):
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placeholder = '%s(%%s, %s)' % (self.transform, f.srid)
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else:
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placeholder = '%s'
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# No geometry value used for F expression, substitue in
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# the column name instead.
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return placeholder % '%s.%s' % tuple(map(self.quote_name, value.cols[value.expression]))
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else:
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if transform_value(value, f.srid):
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# Adding Transform() to the SQL placeholder.
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return '%s(%s(%%s,%s), %s)' % (self.transform, self.from_text, value.srid, f.srid)
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else:
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return '%s(%%s,%s)' % (self.from_text, f.srid)
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def _get_spatialite_func(self, func):
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"""
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Helper routine for calling PostGIS functions and returning their result.
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"""
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cursor = self.connection._cursor()
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try:
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cursor.execute('SELECT %s()' % func)
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row = cursor.fetchone()
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except:
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# TODO: raise helpful exception here.
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raise
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finally:
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cursor.close()
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return row[0]
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def geos_version(self):
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"Returns the version of GEOS used by SpatiaLite as a string."
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return self._get_spatialite_func('geos_version')
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def proj4_version(self):
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"Returns the version of the PROJ.4 library used by SpatiaLite."
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return self._get_spatialite_func('proj4_version')
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def spatialite_version(self):
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"Returns the SpatiaLite library version as a string."
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return self._get_spatialite_func('spatialite_version')
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def spatialite_version_tuple(self):
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"""
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Returns the SpatiaLite version as a tuple (version string, major,
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minor, subminor).
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"""
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# Getting the PostGIS version
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version = self.spatialite_version()
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m = self.version_regex.match(version)
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if m:
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major = int(m.group('major'))
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minor1 = int(m.group('minor1'))
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minor2 = int(m.group('minor2'))
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else:
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raise Exception('Could not parse SpatiaLite version string: %s' % version)
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return (version, major, minor1, minor2)
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def spatial_aggregate_sql(self, agg):
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"""
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Returns the spatial aggregate SQL template and function for the
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given Aggregate instance.
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"""
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agg_name = agg.__class__.__name__
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if not self.check_aggregate_support(agg):
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raise NotImplementedError('%s spatial aggregate is not implmented for this backend.' % agg_name)
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agg_name = agg_name.lower()
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if agg_name == 'union': agg_name += 'agg'
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sql_template = self.select % '%(function)s(%(field)s)'
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sql_function = getattr(self, agg_name)
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return sql_template, sql_function
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def spatial_lookup_sql(self, lvalue, lookup_type, value, field, qn):
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"""
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Returns the SpatiaLite-specific SQL for the given lookup value
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[a tuple of (alias, column, db_type)], lookup type, lookup
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value, and the model field.
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"""
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alias, col, db_type = lvalue
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# Getting the quoted field as `geo_col`.
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geo_col = '%s.%s' % (qn(alias), qn(col))
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if lookup_type in self.geometry_functions:
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# See if a SpatiaLite geometry function matches the lookup type.
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tmp = self.geometry_functions[lookup_type]
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# Lookup types that are tuples take tuple arguments, e.g., 'relate' and
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# distance lookups.
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if isinstance(tmp, tuple):
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# First element of tuple is the SpatiaLiteOperation instance, and the
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# second element is either the type or a tuple of acceptable types
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# that may passed in as further parameters for the lookup type.
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op, arg_type = tmp
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# Ensuring that a tuple _value_ was passed in from the user
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if not isinstance(value, (tuple, list)):
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raise ValueError('Tuple required for `%s` lookup type.' % lookup_type)
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# Geometry is first element of lookup tuple.
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geom = value[0]
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# Number of valid tuple parameters depends on the lookup type.
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if len(value) != 2:
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raise ValueError('Incorrect number of parameters given for `%s` lookup type.' % lookup_type)
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# Ensuring the argument type matches what we expect.
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if not isinstance(value[1], arg_type):
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raise ValueError('Argument type should be %s, got %s instead.' % (arg_type, type(value[1])))
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# For lookup type `relate`, the op instance is not yet created (has
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# to be instantiated here to check the pattern parameter).
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if lookup_type == 'relate':
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op = op(value[1])
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elif lookup_type in self.distance_functions:
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op = op[0]
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else:
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op = tmp
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geom = value
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# Calling the `as_sql` function on the operation instance.
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return op.as_sql(geo_col, self.get_geom_placeholder(field, geom))
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elif lookup_type == 'isnull':
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# Handling 'isnull' lookup type
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return "%s IS %sNULL" % (geo_col, (not value and 'NOT ' or ''))
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raise TypeError("Got invalid lookup_type: %s" % repr(lookup_type))
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# Routines for getting the OGC-compliant models.
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def geometry_columns(self):
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from django.contrib.gis.db.backends.spatialite.models import GeometryColumns
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return GeometryColumns
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def spatial_ref_sys(self):
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from django.contrib.gis.db.backends.spatialite.models import SpatialRefSys
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return SpatialRefSys
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