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from django.db import connection
from django.db.backends.util import truncate_name
from django.db.models.fields import Field # Django base Field class
from django.contrib.gis.db.backend.util import gqn
from django.contrib.gis.db.backend.oracle.query import TRANSFORM
# Quotename & geographic quotename, respectively.
qn = connection.ops.quote_name
class OracleSpatialField(Field):
"""
The backend-specific geographic field for Oracle Spatial.
"""
empty_strings_allowed = False
def __init__(self, extent=(-180.0, -90.0, 180.0, 90.0), tolerance=0.05, **kwargs):
"""
Oracle Spatial backend needs to have the extent -- for projected coordinate
systems _you must define the extent manually_, since the coordinates are
for geodetic systems. The `tolerance` keyword specifies the tolerance
for error (in meters), and defaults to 0.05 (5 centimeters).
"""
# Oracle Spatial specific keyword arguments.
self._extent = extent
self._tolerance = tolerance
# Calling the Django field initialization.
super(OracleSpatialField, self).__init__(**kwargs)
def _add_geom(self, style, db_table):
"""
Adds this geometry column into the Oracle USER_SDO_GEOM_METADATA
table.
"""
# Checking the dimensions.
# TODO: Add support for 3D geometries.
if self._dim != 2:
raise Exception('3D geometries not yet supported on Oracle Spatial backend.')
# Constructing the SQL that will be used to insert information about
# the geometry column into the USER_GSDO_GEOM_METADATA table.
meta_sql = style.SQL_KEYWORD('INSERT INTO ') + \
style.SQL_TABLE('USER_SDO_GEOM_METADATA') + \
' (%s, %s, %s, %s)\n ' % tuple(map(qn, ['TABLE_NAME', 'COLUMN_NAME', 'DIMINFO', 'SRID'])) + \
style.SQL_KEYWORD(' VALUES ') + '(\n ' + \
style.SQL_TABLE(gqn(db_table)) + ',\n ' + \
style.SQL_FIELD(gqn(self.column)) + ',\n ' + \
style.SQL_KEYWORD("MDSYS.SDO_DIM_ARRAY") + '(\n ' + \
style.SQL_KEYWORD("MDSYS.SDO_DIM_ELEMENT") + \
("('LONG', %s, %s, %s),\n " % (self._extent[0], self._extent[2], self._tolerance)) + \
style.SQL_KEYWORD("MDSYS.SDO_DIM_ELEMENT") + \
("('LAT', %s, %s, %s)\n ),\n" % (self._extent[1], self._extent[3], self._tolerance)) + \
' %s\n );' % self._srid
return meta_sql
def _geom_index(self, style, db_table):
"Creates an Oracle Geometry index (R-tree) for this geometry field."
# Getting the index name, Oracle doesn't allow object
# names > 30 characters.
idx_name = truncate_name('%s_%s_id' % (db_table, self.column), 30)
sql = style.SQL_KEYWORD('CREATE INDEX ') + \
style.SQL_TABLE(qn(idx_name)) + \
style.SQL_KEYWORD(' ON ') + \
style.SQL_TABLE(qn(db_table)) + '(' + \
style.SQL_FIELD(qn(self.column)) + ') ' + \
style.SQL_KEYWORD('INDEXTYPE IS ') + \
style.SQL_TABLE('MDSYS.SPATIAL_INDEX') + ';'
return sql
def _post_create_sql(self, style, db_table):
"""
Returns SQL that will be executed after the model has been
created.
"""
# Getting the meta geometry information.
post_sql = self._add_geom(style, db_table)
# Getting the geometric index for this Geometry column.
if self._index:
return (post_sql, self._geom_index(style, db_table))
else:
return (post_sql,)
def db_type(self):
"The Oracle geometric data type is MDSYS.SDO_GEOMETRY."
return 'MDSYS.SDO_GEOMETRY'
def get_placeholder(self, value):
"""
Provides a proper substitution value for Geometries that are not in the
SRID of the field. Specifically, this routine will substitute in the
SDO_CS.TRANSFORM() function call.
"""
if value is None:
return '%s'
elif value.srid != self._srid:
# Adding Transform() to the SQL placeholder.
return '%s(SDO_GEOMETRY(%%s, %s), %s)' % (TRANSFORM, value.srid, self._srid)
else:
return 'SDO_GEOMETRY(%%s, %s)' % self._srid
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