--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/app/django/db/backends/oracle/query.py Fri Jul 18 18:22:23 2008 +0000
@@ -0,0 +1,151 @@
+"""
+Custom Query class for Oracle.
+Derives from: django.db.models.sql.query.Query
+"""
+
+import datetime
+
+from django.db.backends import util
+
+# Cache. Maps default query class to new Oracle query class.
+_classes = {}
+
+def query_class(QueryClass, Database):
+ """
+ Returns a custom django.db.models.sql.query.Query subclass that is
+ appropriate for Oracle.
+
+ The 'Database' module (cx_Oracle) is passed in here so that all the setup
+ required to import it only needs to be done by the calling module.
+ """
+ global _classes
+ try:
+ return _classes[QueryClass]
+ except KeyError:
+ pass
+
+ class OracleQuery(QueryClass):
+ def resolve_columns(self, row, fields=()):
+ index_start = len(self.extra_select.keys())
+ values = [self.convert_values(v, None) for v in row[:index_start]]
+ for value, field in map(None, row[index_start:], fields):
+ values.append(self.convert_values(value, field))
+ return values
+
+ def convert_values(self, value, field):
+ from django.db.models.fields import DateField, DateTimeField, \
+ TimeField, BooleanField, NullBooleanField, DecimalField, Field
+ if isinstance(value, Database.LOB):
+ value = value.read()
+ # Oracle stores empty strings as null. We need to undo this in
+ # order to adhere to the Django convention of using the empty
+ # string instead of null, but only if the field accepts the
+ # empty string.
+ if value is None and isinstance(field, Field) and field.empty_strings_allowed:
+ value = u''
+ # Convert 1 or 0 to True or False
+ elif value in (1, 0) and isinstance(field, (BooleanField, NullBooleanField)):
+ value = bool(value)
+ # Convert floats to decimals
+ elif value is not None and isinstance(field, DecimalField):
+ value = util.typecast_decimal(field.format_number(value))
+ # cx_Oracle always returns datetime.datetime objects for
+ # DATE and TIMESTAMP columns, but Django wants to see a
+ # python datetime.date, .time, or .datetime. We use the type
+ # of the Field to determine which to cast to, but it's not
+ # always available.
+ # As a workaround, we cast to date if all the time-related
+ # values are 0, or to time if the date is 1/1/1900.
+ # This could be cleaned a bit by adding a method to the Field
+ # classes to normalize values from the database (the to_python
+ # method is used for validation and isn't what we want here).
+ elif isinstance(value, Database.Timestamp):
+ # In Python 2.3, the cx_Oracle driver returns its own
+ # Timestamp object that we must convert to a datetime class.
+ if not isinstance(value, datetime.datetime):
+ value = datetime.datetime(value.year, value.month,
+ value.day, value.hour, value.minute, value.second,
+ value.fsecond)
+ if isinstance(field, DateTimeField):
+ # DateTimeField subclasses DateField so must be checked
+ # first.
+ pass
+ elif isinstance(field, DateField):
+ value = value.date()
+ elif isinstance(field, TimeField) or (value.year == 1900 and value.month == value.day == 1):
+ value = value.time()
+ elif value.hour == value.minute == value.second == value.microsecond == 0:
+ value = value.date()
+ return value
+
+ def as_sql(self, with_limits=True, with_col_aliases=False):
+ """
+ Creates the SQL for this query. Returns the SQL string and list
+ of parameters. This is overriden from the original Query class
+ to accommodate Oracle's limit/offset SQL.
+
+ If 'with_limits' is False, any limit/offset information is not
+ included in the query.
+ """
+ # The `do_offset` flag indicates whether we need to construct
+ # the SQL needed to use limit/offset w/Oracle.
+ do_offset = with_limits and (self.high_mark or self.low_mark)
+
+ # If no offsets, just return the result of the base class
+ # `as_sql`.
+ if not do_offset:
+ return super(OracleQuery, self).as_sql(with_limits=False,
+ with_col_aliases=with_col_aliases)
+
+ # `get_columns` needs to be called before `get_ordering` to
+ # populate `_select_alias`.
+ self.pre_sql_setup()
+ out_cols = self.get_columns()
+ ordering = self.get_ordering()
+
+ # Getting the "ORDER BY" SQL for the ROW_NUMBER() result.
+ if ordering:
+ rn_orderby = ', '.join(ordering)
+ else:
+ # Oracle's ROW_NUMBER() function always requires an
+ # order-by clause. So we need to define a default
+ # order-by, since none was provided.
+ qn = self.quote_name_unless_alias
+ opts = self.model._meta
+ rn_orderby = '%s.%s' % (qn(opts.db_table), qn(opts.fields[0].db_column or opts.fields[0].column))
+
+ # Getting the selection SQL and the params, which has the `rn`
+ # extra selection SQL.
+ self.extra_select['rn'] = 'ROW_NUMBER() OVER (ORDER BY %s )' % rn_orderby
+ sql, params= super(OracleQuery, self).as_sql(with_limits=False,
+ with_col_aliases=True)
+
+ # Constructing the result SQL, using the initial select SQL
+ # obtained above.
+ result = ['SELECT * FROM (%s)' % sql]
+
+ # Place WHERE condition on `rn` for the desired range.
+ result.append('WHERE rn > %d' % self.low_mark)
+ if self.high_mark:
+ result.append('AND rn <= %d' % self.high_mark)
+
+ # Returning the SQL w/params.
+ return ' '.join(result), params
+
+ def set_limits(self, low=None, high=None):
+ super(OracleQuery, self).set_limits(low, high)
+
+ # We need to select the row number for the LIMIT/OFFSET sql.
+ # A placeholder is added to extra_select now, because as_sql is
+ # too late to be modifying extra_select. However, the actual sql
+ # depends on the ordering, so that is generated in as_sql.
+ self.extra_select['rn'] = '1'
+
+ def clear_limits(self):
+ super(OracleQuery, self).clear_limits()
+ if 'rn' in self.extra_select:
+ del self.extra_select['rn']
+
+ _classes[QueryClass] = OracleQuery
+ return OracleQuery
+