app/django/contrib/gis/db/backend/oracle/field.py
author Sverre Rabbelier <srabbelier@gmail.com>
Sun, 07 Dec 2008 17:02:10 +0000
changeset 705 0ab17e14df95
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
Move document sidebar entries extraction to document.View This way other modules can benefit from the same logic. Also make use of the sidebar.getSidebarMenu method so that getMenusForScope is no longer specific to full menu's. Patch by: Sverre Rabbelier

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