1 from django.db import connection

     2 from django.db.backends.util import truncate_name

     3 from django.db.models.fields import Field # Django base Field class

     4 from django.contrib.gis.db.backend.util import gqn

     5 from django.contrib.gis.db.backend.oracle.query import TRANSFORM

     6 

     7 # Quotename & geographic quotename, respectively.

     8 qn = connection.ops.quote_name

     9 

    10 class OracleSpatialField(Field):

    11     """

    12     The backend-specific geographic field for Oracle Spatial.

    13     """

    14 

    15     empty_strings_allowed = False

    16 

    17     def __init__(self, extent=(-180.0, -90.0, 180.0, 90.0), tolerance=0.05, **kwargs):

    18         """

    19         Oracle Spatial backend needs to have the extent -- for projected coordinate

    20         systems _you must define the extent manually_, since the coordinates are

    21         for geodetic systems.  The `tolerance` keyword specifies the tolerance

    22         for error (in meters), and defaults to 0.05 (5 centimeters).

    23         """

    24         # Oracle Spatial specific keyword arguments.

    25         self._extent = extent

    26         self._tolerance = tolerance

    27         # Calling the Django field initialization.

    28         super(OracleSpatialField, self).__init__(**kwargs)

    29 

    30     def _add_geom(self, style, db_table):

    31         """

    32         Adds this geometry column into the Oracle USER_SDO_GEOM_METADATA

    33         table.

    34         """

    35 

    36         # Checking the dimensions.

    37         # TODO: Add support for 3D geometries.

    38         if self._dim != 2:

    39             raise Exception('3D geometries not yet supported on Oracle Spatial backend.')

    40 

    41         # Constructing the SQL that will be used to insert information about

    42         # the geometry column into the USER_GSDO_GEOM_METADATA table.

    43         meta_sql = style.SQL_KEYWORD('INSERT INTO ') + \

    44                    style.SQL_TABLE('USER_SDO_GEOM_METADATA') + \

    45                    ' (%s, %s, %s, %s)\n  ' % tuple(map(qn, ['TABLE_NAME', 'COLUMN_NAME', 'DIMINFO', 'SRID'])) + \

    46                    style.SQL_KEYWORD(' VALUES ') + '(\n    ' + \

    47                    style.SQL_TABLE(gqn(db_table)) + ',\n    ' + \

    48                    style.SQL_FIELD(gqn(self.column)) + ',\n    ' + \

    49                    style.SQL_KEYWORD("MDSYS.SDO_DIM_ARRAY") + '(\n      ' + \

    50                    style.SQL_KEYWORD("MDSYS.SDO_DIM_ELEMENT") + \

    51                    ("('LONG', %s, %s, %s),\n      " % (self._extent[0], self._extent[2], self._tolerance)) + \

    52                    style.SQL_KEYWORD("MDSYS.SDO_DIM_ELEMENT") + \

    53                    ("('LAT', %s, %s, %s)\n    ),\n" % (self._extent[1], self._extent[3], self._tolerance)) + \

    54                    '    %s\n  );' % self._srid

    55         return meta_sql

    56 

    57     def _geom_index(self, style, db_table):

    58         "Creates an Oracle Geometry index (R-tree) for this geometry field."

    59 

    60         # Getting the index name, Oracle doesn't allow object

    61         # names > 30 characters.

    62         idx_name = truncate_name('%s_%s_id' % (db_table, self.column), 30)

    63         

    64         sql = style.SQL_KEYWORD('CREATE INDEX ') + \

    65               style.SQL_TABLE(qn(idx_name)) + \

    66               style.SQL_KEYWORD(' ON ') + \

    67               style.SQL_TABLE(qn(db_table)) + '(' + \

    68               style.SQL_FIELD(qn(self.column)) + ') ' + \

    69               style.SQL_KEYWORD('INDEXTYPE IS ') + \

    70               style.SQL_TABLE('MDSYS.SPATIAL_INDEX') + ';'

    71         return sql

    72 

    73     def post_create_sql(self, style, db_table):

    74         """

    75         Returns SQL that will be executed after the model has been

    76         created.

    77         """

    78         # Getting the meta geometry information.

    79         post_sql = self._add_geom(style, db_table)

    80 

    81         # Getting the geometric index for this Geometry column.

    82         if self._index:

    83             return (post_sql, self._geom_index(style, db_table))

    84         else:

    85             return (post_sql,)

    86 

    87     def db_type(self):

    88         "The Oracle geometric data type is MDSYS.SDO_GEOMETRY."

    89         return 'MDSYS.SDO_GEOMETRY'

    90         

    91     def get_placeholder(self, value):

    92         """

    93         Provides a proper substitution value for Geometries that are not in the

    94         SRID of the field.  Specifically, this routine will substitute in the

    95         SDO_CS.TRANSFORM() function call.

    96         """

    97         if value is None:

    98             return '%s'

    99         elif value.srid != self._srid:

   100             # Adding Transform() to the SQL placeholder.

   101             return '%s(SDO_GEOMETRY(%%s, %s), %s)' % (TRANSFORM, value.srid, self._srid)

   102         else:

   103             return 'SDO_GEOMETRY(%%s, %s)' % self._srid