Refactored get_query_set_class() to DatabaseOperations.query_set_class(). Also added BaseDatabaseFeatures.uses_custom_queryset. Refs #5106

git-svn-id: http://code.djangoproject.com/svn/django/trunk@5976 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Adrian Holovaty 2007-08-20 02:39:05 +00:00
parent 6d8e6090e5
commit e13ea3c70d
3 changed files with 251 additions and 243 deletions

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@ -48,6 +48,7 @@ class BaseDatabaseFeatures(object):
supports_constraints = True supports_constraints = True
supports_tablespaces = False supports_tablespaces = False
uses_case_insensitive_names = False uses_case_insensitive_names = False
uses_custom_queryset = False
class BaseDatabaseOperations(object): class BaseDatabaseOperations(object):
""" """
@ -144,6 +145,15 @@ class BaseDatabaseOperations(object):
""" """
return 'DEFAULT' return 'DEFAULT'
def query_set_class(self, DefaultQuerySet):
"""
Given the default QuerySet class, returns a custom QuerySet class
to use for this backend. Returns None if a custom QuerySet isn't used.
See also BaseDatabaseFeatures.uses_custom_queryset, which regulates
whether this method is called at all.
"""
return None
def quote_name(self, name): def quote_name(self, name):
""" """
Returns a quoted version of the given table, index or column name. Does Returns a quoted version of the given table, index or column name. Does

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@ -28,6 +28,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
needs_upper_for_iops = True needs_upper_for_iops = True
supports_tablespaces = True supports_tablespaces = True
uses_case_insensitive_names = True uses_case_insensitive_names = True
uses_custom_queryset = True
class DatabaseOperations(BaseDatabaseOperations): class DatabaseOperations(BaseDatabaseOperations):
def autoinc_sql(self, table): def autoinc_sql(self, table):
@ -78,6 +79,243 @@ class DatabaseOperations(BaseDatabaseOperations):
def max_name_length(self): def max_name_length(self):
return 30 return 30
def query_set_class(self, DefaultQuerySet):
from django.db import connection
from django.db.models.query import EmptyResultSet, GET_ITERATOR_CHUNK_SIZE, quote_only_if_word
class OracleQuerySet(DefaultQuerySet):
def iterator(self):
"Performs the SELECT database lookup of this QuerySet."
from django.db.models.query import get_cached_row
# self._select is a dictionary, and dictionaries' key order is
# undefined, so we convert it to a list of tuples.
extra_select = self._select.items()
full_query = None
try:
try:
select, sql, params, full_query = self._get_sql_clause(get_full_query=True)
except TypeError:
select, sql, params = self._get_sql_clause()
except EmptyResultSet:
raise StopIteration
if not full_query:
full_query = "SELECT %s%s\n%s" % \
((self._distinct and "DISTINCT " or ""),
', '.join(select), sql)
cursor = connection.cursor()
cursor.execute(full_query, params)
fill_cache = self._select_related
fields = self.model._meta.fields
index_end = len(fields)
# so here's the logic;
# 1. retrieve each row in turn
# 2. convert NCLOBs
while 1:
rows = cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE)
if not rows:
raise StopIteration
for row in rows:
row = self.resolve_columns(row, fields)
if fill_cache:
obj, index_end = get_cached_row(klass=self.model, row=row,
index_start=0, max_depth=self._max_related_depth)
else:
obj = self.model(*row[:index_end])
for i, k in enumerate(extra_select):
setattr(obj, k[0], row[index_end+i])
yield obj
def _get_sql_clause(self, get_full_query=False):
from django.db.models.query import fill_table_cache, \
handle_legacy_orderlist, orderfield2column
opts = self.model._meta
qn = connection.ops.quote_name
# Construct the fundamental parts of the query: SELECT X FROM Y WHERE Z.
select = ["%s.%s" % (qn(opts.db_table), qn(f.column)) for f in opts.fields]
tables = [quote_only_if_word(t) for t in self._tables]
joins = SortedDict()
where = self._where[:]
params = self._params[:]
# Convert self._filters into SQL.
joins2, where2, params2 = self._filters.get_sql(opts)
joins.update(joins2)
where.extend(where2)
params.extend(params2)
# Add additional tables and WHERE clauses based on select_related.
if self._select_related:
fill_table_cache(opts, select, tables, where, opts.db_table, [opts.db_table])
# Add any additional SELECTs.
if self._select:
select.extend(['(%s) AS %s' % (quote_only_if_word(s[1]), qn(s[0])) for s in self._select.items()])
# Start composing the body of the SQL statement.
sql = [" FROM", qn(opts.db_table)]
# Compose the join dictionary into SQL describing the joins.
if joins:
sql.append(" ".join(["%s %s %s ON %s" % (join_type, table, alias, condition)
for (alias, (table, join_type, condition)) in joins.items()]))
# Compose the tables clause into SQL.
if tables:
sql.append(", " + ", ".join(tables))
# Compose the where clause into SQL.
if where:
sql.append(where and "WHERE " + " AND ".join(where))
# ORDER BY clause
order_by = []
if self._order_by is not None:
ordering_to_use = self._order_by
else:
ordering_to_use = opts.ordering
for f in handle_legacy_orderlist(ordering_to_use):
if f == '?': # Special case.
order_by.append(DatabaseOperations().random_function_sql())
else:
if f.startswith('-'):
col_name = f[1:]
order = "DESC"
else:
col_name = f
order = "ASC"
if "." in col_name:
table_prefix, col_name = col_name.split('.', 1)
table_prefix = qn(table_prefix) + '.'
else:
# Use the database table as a column prefix if it wasn't given,
# and if the requested column isn't a custom SELECT.
if "." not in col_name and col_name not in (self._select or ()):
table_prefix = qn(opts.db_table) + '.'
else:
table_prefix = ''
order_by.append('%s%s %s' % (table_prefix, qn(orderfield2column(col_name, opts)), order))
if order_by:
sql.append("ORDER BY " + ", ".join(order_by))
# Look for column name collisions in the select elements
# and fix them with an AS alias. This allows us to do a
# SELECT * later in the paging query.
cols = [clause.split('.')[-1] for clause in select]
for index, col in enumerate(cols):
if cols.count(col) > 1:
col = '%s%d' % (col.replace('"', ''), index)
cols[index] = col
select[index] = '%s AS %s' % (select[index], col)
# LIMIT and OFFSET clauses
# To support limits and offsets, Oracle requires some funky rewriting of an otherwise normal looking query.
select_clause = ",".join(select)
distinct = (self._distinct and "DISTINCT " or "")
if order_by:
order_by_clause = " OVER (ORDER BY %s )" % (", ".join(order_by))
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.
order_by_clause = " OVER (ORDER BY %s.%s)" % \
(qn(opts.db_table), qn(opts.fields[0].db_column or opts.fields[0].column))
# limit_and_offset_clause
if self._limit is None:
assert self._offset is None, "'offset' is not allowed without 'limit'"
if self._offset is not None:
offset = int(self._offset)
else:
offset = 0
if self._limit is not None:
limit = int(self._limit)
else:
limit = None
limit_and_offset_clause = ''
if limit is not None:
limit_and_offset_clause = "WHERE rn > %s AND rn <= %s" % (offset, limit+offset)
elif offset:
limit_and_offset_clause = "WHERE rn > %s" % (offset)
if len(limit_and_offset_clause) > 0:
fmt = \
"""SELECT * FROM
(SELECT %s%s,
ROW_NUMBER()%s AS rn
%s)
%s"""
full_query = fmt % (distinct, select_clause,
order_by_clause, ' '.join(sql).strip(),
limit_and_offset_clause)
else:
full_query = None
if get_full_query:
return select, " ".join(sql), params, full_query
else:
return select, " ".join(sql), params
def resolve_columns(self, row, fields=()):
from django.db.models.fields import DateField, DateTimeField, \
TimeField, BooleanField, NullBooleanField, DecimalField, Field
values = []
for value, field in map(None, row, fields):
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 = ''
# 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):
pass # DateTimeField subclasses DateField so must be checked first.
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()
values.append(value)
return values
return OracleQuerySet
def quote_name(self, name): def quote_name(self, name):
# SQL92 requires delimited (quoted) names to be case-sensitive. When # SQL92 requires delimited (quoted) names to be case-sensitive. When
# not quoted, Oracle has case-insensitive behavior for identifiers, but # not quoted, Oracle has case-insensitive behavior for identifiers, but
@ -261,246 +499,6 @@ def get_trigger_name(table):
name_length = DatabaseOperations().max_name_length() - 3 name_length = DatabaseOperations().max_name_length() - 3
return '%s_TR' % util.truncate_name(table, name_length).upper() return '%s_TR' % util.truncate_name(table, name_length).upper()
def get_query_set_class(DefaultQuerySet):
"Create a custom QuerySet class for Oracle."
from django.db import connection
from django.db.models.query import EmptyResultSet, GET_ITERATOR_CHUNK_SIZE, quote_only_if_word
class OracleQuerySet(DefaultQuerySet):
def iterator(self):
"Performs the SELECT database lookup of this QuerySet."
from django.db.models.query import get_cached_row
# self._select is a dictionary, and dictionaries' key order is
# undefined, so we convert it to a list of tuples.
extra_select = self._select.items()
full_query = None
try:
try:
select, sql, params, full_query = self._get_sql_clause(get_full_query=True)
except TypeError:
select, sql, params = self._get_sql_clause()
except EmptyResultSet:
raise StopIteration
if not full_query:
full_query = "SELECT %s%s\n%s" % \
((self._distinct and "DISTINCT " or ""),
', '.join(select), sql)
cursor = connection.cursor()
cursor.execute(full_query, params)
fill_cache = self._select_related
fields = self.model._meta.fields
index_end = len(fields)
# so here's the logic;
# 1. retrieve each row in turn
# 2. convert NCLOBs
while 1:
rows = cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE)
if not rows:
raise StopIteration
for row in rows:
row = self.resolve_columns(row, fields)
if fill_cache:
obj, index_end = get_cached_row(klass=self.model, row=row,
index_start=0, max_depth=self._max_related_depth)
else:
obj = self.model(*row[:index_end])
for i, k in enumerate(extra_select):
setattr(obj, k[0], row[index_end+i])
yield obj
def _get_sql_clause(self, get_full_query=False):
from django.db.models.query import fill_table_cache, \
handle_legacy_orderlist, orderfield2column
opts = self.model._meta
qn = connection.ops.quote_name
# Construct the fundamental parts of the query: SELECT X FROM Y WHERE Z.
select = ["%s.%s" % (qn(opts.db_table), qn(f.column)) for f in opts.fields]
tables = [quote_only_if_word(t) for t in self._tables]
joins = SortedDict()
where = self._where[:]
params = self._params[:]
# Convert self._filters into SQL.
joins2, where2, params2 = self._filters.get_sql(opts)
joins.update(joins2)
where.extend(where2)
params.extend(params2)
# Add additional tables and WHERE clauses based on select_related.
if self._select_related:
fill_table_cache(opts, select, tables, where, opts.db_table, [opts.db_table])
# Add any additional SELECTs.
if self._select:
select.extend(['(%s) AS %s' % (quote_only_if_word(s[1]), qn(s[0])) for s in self._select.items()])
# Start composing the body of the SQL statement.
sql = [" FROM", qn(opts.db_table)]
# Compose the join dictionary into SQL describing the joins.
if joins:
sql.append(" ".join(["%s %s %s ON %s" % (join_type, table, alias, condition)
for (alias, (table, join_type, condition)) in joins.items()]))
# Compose the tables clause into SQL.
if tables:
sql.append(", " + ", ".join(tables))
# Compose the where clause into SQL.
if where:
sql.append(where and "WHERE " + " AND ".join(where))
# ORDER BY clause
order_by = []
if self._order_by is not None:
ordering_to_use = self._order_by
else:
ordering_to_use = opts.ordering
for f in handle_legacy_orderlist(ordering_to_use):
if f == '?': # Special case.
order_by.append(DatabaseOperations().random_function_sql())
else:
if f.startswith('-'):
col_name = f[1:]
order = "DESC"
else:
col_name = f
order = "ASC"
if "." in col_name:
table_prefix, col_name = col_name.split('.', 1)
table_prefix = qn(table_prefix) + '.'
else:
# Use the database table as a column prefix if it wasn't given,
# and if the requested column isn't a custom SELECT.
if "." not in col_name and col_name not in (self._select or ()):
table_prefix = qn(opts.db_table) + '.'
else:
table_prefix = ''
order_by.append('%s%s %s' % (table_prefix, qn(orderfield2column(col_name, opts)), order))
if order_by:
sql.append("ORDER BY " + ", ".join(order_by))
# Look for column name collisions in the select elements
# and fix them with an AS alias. This allows us to do a
# SELECT * later in the paging query.
cols = [clause.split('.')[-1] for clause in select]
for index, col in enumerate(cols):
if cols.count(col) > 1:
col = '%s%d' % (col.replace('"', ''), index)
cols[index] = col
select[index] = '%s AS %s' % (select[index], col)
# LIMIT and OFFSET clauses
# To support limits and offsets, Oracle requires some funky rewriting of an otherwise normal looking query.
select_clause = ",".join(select)
distinct = (self._distinct and "DISTINCT " or "")
if order_by:
order_by_clause = " OVER (ORDER BY %s )" % (", ".join(order_by))
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.
order_by_clause = " OVER (ORDER BY %s.%s)" % \
(qn(opts.db_table), qn(opts.fields[0].db_column or opts.fields[0].column))
# limit_and_offset_clause
if self._limit is None:
assert self._offset is None, "'offset' is not allowed without 'limit'"
if self._offset is not None:
offset = int(self._offset)
else:
offset = 0
if self._limit is not None:
limit = int(self._limit)
else:
limit = None
limit_and_offset_clause = ''
if limit is not None:
limit_and_offset_clause = "WHERE rn > %s AND rn <= %s" % (offset, limit+offset)
elif offset:
limit_and_offset_clause = "WHERE rn > %s" % (offset)
if len(limit_and_offset_clause) > 0:
fmt = \
"""SELECT * FROM
(SELECT %s%s,
ROW_NUMBER()%s AS rn
%s)
%s"""
full_query = fmt % (distinct, select_clause,
order_by_clause, ' '.join(sql).strip(),
limit_and_offset_clause)
else:
full_query = None
if get_full_query:
return select, " ".join(sql), params, full_query
else:
return select, " ".join(sql), params
def resolve_columns(self, row, fields=()):
from django.db.models.fields import DateField, DateTimeField, \
TimeField, BooleanField, NullBooleanField, DecimalField, Field
values = []
for value, field in map(None, row, fields):
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 = ''
# 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):
pass # DateTimeField subclasses DateField so must be checked first.
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()
values.append(value)
return values
return OracleQuerySet
OPERATOR_MAPPING = { OPERATOR_MAPPING = {
'exact': '= %s', 'exact': '= %s',
'iexact': '= UPPER(%s)', 'iexact': '= UPPER(%s)',

View File

@ -564,9 +564,9 @@ class _QuerySet(object):
return select, " ".join(sql), params return select, " ".join(sql), params
# Use the backend's QuerySet class if it defines one, otherwise use _QuerySet. # Use the backend's QuerySet class if it defines one. Otherwise, use _QuerySet.
if hasattr(backend, 'get_query_set_class'): if connection.features.uses_custom_queryset:
QuerySet = backend.get_query_set_class(_QuerySet) QuerySet = connection.ops.query_set_class(_QuerySet)
else: else:
QuerySet = _QuerySet QuerySet = _QuerySet