--- /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