--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/app/django/contrib/gis/db/backend/mysql/field.py Tue Oct 14 16:00:59 2008 +0000
@@ -0,0 +1,53 @@
+from django.db import connection
+from django.db.models.fields import Field # Django base Field class
+from django.contrib.gis.db.backend.mysql.query import GEOM_FROM_TEXT
+
+# Quotename & geographic quotename, respectively.
+qn = connection.ops.quote_name
+
+class MySQLGeoField(Field):
+ """
+ The backend-specific geographic field for MySQL.
+ """
+
+ def _geom_index(self, style, db_table):
+ """
+ Creates a spatial index for the geometry column. If MyISAM tables are
+ used an R-Tree index is created, otherwise a B-Tree index is created.
+ Thus, for best spatial performance, you should use MyISAM tables
+ (which do not support transactions). For more information, see Ch.
+ 16.6.1 of the MySQL 5.0 documentation.
+ """
+
+ # Getting the index name.
+ idx_name = '%s_%s_id' % (db_table, self.column)
+
+ sql = style.SQL_KEYWORD('CREATE SPATIAL INDEX ') + \
+ style.SQL_TABLE(qn(idx_name)) + \
+ style.SQL_KEYWORD(' ON ') + \
+ style.SQL_TABLE(qn(db_table)) + '(' + \
+ style.SQL_FIELD(qn(self.column)) + ');'
+ return sql
+
+ def _post_create_sql(self, style, db_table):
+ """
+ Returns SQL that will be executed after the model has been
+ created.
+ """
+ # Getting the geometric index for this Geometry column.
+ if self._index:
+ return (self._geom_index(style, db_table),)
+ else:
+ return ()
+
+ def db_type(self):
+ "The OpenGIS name is returned for the MySQL database column type."
+ return self._geom
+
+ def get_placeholder(self, value):
+ """
+ The placeholder here has to include MySQL's WKT constructor. Because
+ MySQL does not support spatial transformations, there is no need to
+ modify the placeholder based on the contents of the given value.
+ """
+ return '%s(%%s)' % GEOM_FROM_TEXT