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