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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
@@ -48,6 +48,7 @@ class BaseDatabaseFeatures(object):
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supports_constraints = True
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supports_tablespaces = False
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uses_case_insensitive_names = False
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uses_custom_queryset = False
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class BaseDatabaseOperations(object):
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"""
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@@ -144,6 +145,15 @@ class BaseDatabaseOperations(object):
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"""
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return 'DEFAULT'
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def query_set_class(self, DefaultQuerySet):
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"""
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Given the default QuerySet class, returns a custom QuerySet class
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to use for this backend. Returns None if a custom QuerySet isn't used.
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See also BaseDatabaseFeatures.uses_custom_queryset, which regulates
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whether this method is called at all.
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"""
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return None
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def quote_name(self, name):
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"""
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Returns a quoted version of the given table, index or column name. Does
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@@ -28,6 +28,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
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needs_upper_for_iops = True
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supports_tablespaces = True
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uses_case_insensitive_names = True
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uses_custom_queryset = True
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class DatabaseOperations(BaseDatabaseOperations):
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def autoinc_sql(self, table):
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@@ -78,6 +79,243 @@ class DatabaseOperations(BaseDatabaseOperations):
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def max_name_length(self):
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return 30
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def query_set_class(self, DefaultQuerySet):
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from django.db import connection
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from django.db.models.query import EmptyResultSet, GET_ITERATOR_CHUNK_SIZE, quote_only_if_word
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class OracleQuerySet(DefaultQuerySet):
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def iterator(self):
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"Performs the SELECT database lookup of this QuerySet."
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from django.db.models.query import get_cached_row
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# self._select is a dictionary, and dictionaries' key order is
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# undefined, so we convert it to a list of tuples.
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extra_select = self._select.items()
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full_query = None
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try:
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try:
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select, sql, params, full_query = self._get_sql_clause(get_full_query=True)
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except TypeError:
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select, sql, params = self._get_sql_clause()
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except EmptyResultSet:
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raise StopIteration
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if not full_query:
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full_query = "SELECT %s%s\n%s" % \
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((self._distinct and "DISTINCT " or ""),
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', '.join(select), sql)
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cursor = connection.cursor()
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cursor.execute(full_query, params)
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fill_cache = self._select_related
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fields = self.model._meta.fields
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index_end = len(fields)
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# so here's the logic;
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# 1. retrieve each row in turn
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# 2. convert NCLOBs
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while 1:
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rows = cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE)
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if not rows:
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raise StopIteration
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for row in rows:
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row = self.resolve_columns(row, fields)
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if fill_cache:
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obj, index_end = get_cached_row(klass=self.model, row=row,
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index_start=0, max_depth=self._max_related_depth)
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else:
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obj = self.model(*row[:index_end])
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for i, k in enumerate(extra_select):
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setattr(obj, k[0], row[index_end+i])
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yield obj
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def _get_sql_clause(self, get_full_query=False):
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from django.db.models.query import fill_table_cache, \
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handle_legacy_orderlist, orderfield2column
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opts = self.model._meta
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qn = connection.ops.quote_name
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# Construct the fundamental parts of the query: SELECT X FROM Y WHERE Z.
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select = ["%s.%s" % (qn(opts.db_table), qn(f.column)) for f in opts.fields]
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tables = [quote_only_if_word(t) for t in self._tables]
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joins = SortedDict()
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where = self._where[:]
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params = self._params[:]
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# Convert self._filters into SQL.
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joins2, where2, params2 = self._filters.get_sql(opts)
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joins.update(joins2)
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where.extend(where2)
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params.extend(params2)
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# Add additional tables and WHERE clauses based on select_related.
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if self._select_related:
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fill_table_cache(opts, select, tables, where, opts.db_table, [opts.db_table])
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# Add any additional SELECTs.
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if self._select:
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select.extend(['(%s) AS %s' % (quote_only_if_word(s[1]), qn(s[0])) for s in self._select.items()])
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# Start composing the body of the SQL statement.
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sql = [" FROM", qn(opts.db_table)]
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# Compose the join dictionary into SQL describing the joins.
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if joins:
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sql.append(" ".join(["%s %s %s ON %s" % (join_type, table, alias, condition)
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for (alias, (table, join_type, condition)) in joins.items()]))
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# Compose the tables clause into SQL.
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if tables:
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sql.append(", " + ", ".join(tables))
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# Compose the where clause into SQL.
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if where:
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sql.append(where and "WHERE " + " AND ".join(where))
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# ORDER BY clause
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order_by = []
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if self._order_by is not None:
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ordering_to_use = self._order_by
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else:
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ordering_to_use = opts.ordering
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for f in handle_legacy_orderlist(ordering_to_use):
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if f == '?': # Special case.
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order_by.append(DatabaseOperations().random_function_sql())
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else:
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if f.startswith('-'):
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col_name = f[1:]
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order = "DESC"
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else:
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col_name = f
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order = "ASC"
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if "." in col_name:
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table_prefix, col_name = col_name.split('.', 1)
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table_prefix = qn(table_prefix) + '.'
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else:
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# Use the database table as a column prefix if it wasn't given,
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# and if the requested column isn't a custom SELECT.
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if "." not in col_name and col_name not in (self._select or ()):
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table_prefix = qn(opts.db_table) + '.'
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else:
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table_prefix = ''
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order_by.append('%s%s %s' % (table_prefix, qn(orderfield2column(col_name, opts)), order))
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if order_by:
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sql.append("ORDER BY " + ", ".join(order_by))
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# Look for column name collisions in the select elements
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# and fix them with an AS alias. This allows us to do a
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# SELECT * later in the paging query.
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cols = [clause.split('.')[-1] for clause in select]
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for index, col in enumerate(cols):
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if cols.count(col) > 1:
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col = '%s%d' % (col.replace('"', ''), index)
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cols[index] = col
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select[index] = '%s AS %s' % (select[index], col)
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# LIMIT and OFFSET clauses
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# To support limits and offsets, Oracle requires some funky rewriting of an otherwise normal looking query.
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select_clause = ",".join(select)
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distinct = (self._distinct and "DISTINCT " or "")
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if order_by:
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order_by_clause = " OVER (ORDER BY %s )" % (", ".join(order_by))
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else:
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#Oracle's row_number() function always requires an order-by clause.
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#So we need to define a default order-by, since none was provided.
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order_by_clause = " OVER (ORDER BY %s.%s)" % \
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(qn(opts.db_table), qn(opts.fields[0].db_column or opts.fields[0].column))
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# limit_and_offset_clause
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if self._limit is None:
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assert self._offset is None, "'offset' is not allowed without 'limit'"
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if self._offset is not None:
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offset = int(self._offset)
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else:
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offset = 0
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if self._limit is not None:
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limit = int(self._limit)
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else:
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limit = None
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limit_and_offset_clause = ''
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if limit is not None:
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limit_and_offset_clause = "WHERE rn > %s AND rn <= %s" % (offset, limit+offset)
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elif offset:
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limit_and_offset_clause = "WHERE rn > %s" % (offset)
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if len(limit_and_offset_clause) > 0:
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fmt = \
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"""SELECT * FROM
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(SELECT %s%s,
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ROW_NUMBER()%s AS rn
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%s)
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%s"""
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full_query = fmt % (distinct, select_clause,
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order_by_clause, ' '.join(sql).strip(),
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limit_and_offset_clause)
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else:
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full_query = None
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if get_full_query:
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return select, " ".join(sql), params, full_query
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else:
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return select, " ".join(sql), params
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def resolve_columns(self, row, fields=()):
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from django.db.models.fields import DateField, DateTimeField, \
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TimeField, BooleanField, NullBooleanField, DecimalField, Field
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values = []
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for value, field in map(None, row, fields):
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if isinstance(value, Database.LOB):
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value = value.read()
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# Oracle stores empty strings as null. We need to undo this in
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# order to adhere to the Django convention of using the empty
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# string instead of null, but only if the field accepts the
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# empty string.
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if value is None and isinstance(field, Field) and field.empty_strings_allowed:
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value = ''
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# Convert 1 or 0 to True or False
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elif value in (1, 0) and isinstance(field, (BooleanField, NullBooleanField)):
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value = bool(value)
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# Convert floats to decimals
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elif value is not None and isinstance(field, DecimalField):
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value = util.typecast_decimal(field.format_number(value))
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# cx_Oracle always returns datetime.datetime objects for
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# DATE and TIMESTAMP columns, but Django wants to see a
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# python datetime.date, .time, or .datetime. We use the type
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# of the Field to determine which to cast to, but it's not
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# always available.
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# As a workaround, we cast to date if all the time-related
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# values are 0, or to time if the date is 1/1/1900.
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# This could be cleaned a bit by adding a method to the Field
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# classes to normalize values from the database (the to_python
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# method is used for validation and isn't what we want here).
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elif isinstance(value, Database.Timestamp):
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# In Python 2.3, the cx_Oracle driver returns its own
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# Timestamp object that we must convert to a datetime class.
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if not isinstance(value, datetime.datetime):
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value = datetime.datetime(value.year, value.month, value.day, value.hour,
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value.minute, value.second, value.fsecond)
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if isinstance(field, DateTimeField):
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pass # DateTimeField subclasses DateField so must be checked first.
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elif isinstance(field, DateField):
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value = value.date()
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elif isinstance(field, TimeField) or (value.year == 1900 and value.month == value.day == 1):
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value = value.time()
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elif value.hour == value.minute == value.second == value.microsecond == 0:
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value = value.date()
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values.append(value)
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return values
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return OracleQuerySet
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def quote_name(self, name):
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# SQL92 requires delimited (quoted) names to be case-sensitive. When
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# not quoted, Oracle has case-insensitive behavior for identifiers, but
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@@ -261,246 +499,6 @@ def get_trigger_name(table):
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name_length = DatabaseOperations().max_name_length() - 3
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return '%s_TR' % util.truncate_name(table, name_length).upper()
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def get_query_set_class(DefaultQuerySet):
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"Create a custom QuerySet class for Oracle."
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from django.db import connection
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from django.db.models.query import EmptyResultSet, GET_ITERATOR_CHUNK_SIZE, quote_only_if_word
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class OracleQuerySet(DefaultQuerySet):
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def iterator(self):
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"Performs the SELECT database lookup of this QuerySet."
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from django.db.models.query import get_cached_row
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# self._select is a dictionary, and dictionaries' key order is
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# undefined, so we convert it to a list of tuples.
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extra_select = self._select.items()
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full_query = None
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try:
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try:
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select, sql, params, full_query = self._get_sql_clause(get_full_query=True)
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except TypeError:
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select, sql, params = self._get_sql_clause()
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except EmptyResultSet:
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raise StopIteration
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if not full_query:
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full_query = "SELECT %s%s\n%s" % \
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((self._distinct and "DISTINCT " or ""),
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', '.join(select), sql)
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cursor = connection.cursor()
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cursor.execute(full_query, params)
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fill_cache = self._select_related
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fields = self.model._meta.fields
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index_end = len(fields)
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# so here's the logic;
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# 1. retrieve each row in turn
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# 2. convert NCLOBs
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while 1:
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rows = cursor.fetchmany(GET_ITERATOR_CHUNK_SIZE)
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if not rows:
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raise StopIteration
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for row in rows:
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row = self.resolve_columns(row, fields)
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if fill_cache:
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obj, index_end = get_cached_row(klass=self.model, row=row,
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index_start=0, max_depth=self._max_related_depth)
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else:
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obj = self.model(*row[:index_end])
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for i, k in enumerate(extra_select):
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setattr(obj, k[0], row[index_end+i])
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yield obj
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def _get_sql_clause(self, get_full_query=False):
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from django.db.models.query import fill_table_cache, \
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handle_legacy_orderlist, orderfield2column
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opts = self.model._meta
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qn = connection.ops.quote_name
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# Construct the fundamental parts of the query: SELECT X FROM Y WHERE Z.
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select = ["%s.%s" % (qn(opts.db_table), qn(f.column)) for f in opts.fields]
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tables = [quote_only_if_word(t) for t in self._tables]
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joins = SortedDict()
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where = self._where[:]
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params = self._params[:]
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# Convert self._filters into SQL.
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joins2, where2, params2 = self._filters.get_sql(opts)
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joins.update(joins2)
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where.extend(where2)
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params.extend(params2)
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# Add additional tables and WHERE clauses based on select_related.
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if self._select_related:
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fill_table_cache(opts, select, tables, where, opts.db_table, [opts.db_table])
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# Add any additional SELECTs.
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if self._select:
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select.extend(['(%s) AS %s' % (quote_only_if_word(s[1]), qn(s[0])) for s in self._select.items()])
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# Start composing the body of the SQL statement.
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sql = [" FROM", qn(opts.db_table)]
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# Compose the join dictionary into SQL describing the joins.
|
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if joins:
|
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sql.append(" ".join(["%s %s %s ON %s" % (join_type, table, alias, condition)
|
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for (alias, (table, join_type, condition)) in joins.items()]))
|
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|
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# Compose the tables clause into SQL.
|
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if tables:
|
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sql.append(", " + ", ".join(tables))
|
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|
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# Compose the where clause into SQL.
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if where:
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sql.append(where and "WHERE " + " AND ".join(where))
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# ORDER BY clause
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order_by = []
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if self._order_by is not None:
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ordering_to_use = self._order_by
|
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else:
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ordering_to_use = opts.ordering
|
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for f in handle_legacy_orderlist(ordering_to_use):
|
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if f == '?': # Special case.
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order_by.append(DatabaseOperations().random_function_sql())
|
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else:
|
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if f.startswith('-'):
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col_name = f[1:]
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order = "DESC"
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else:
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col_name = f
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order = "ASC"
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if "." in col_name:
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table_prefix, col_name = col_name.split('.', 1)
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table_prefix = qn(table_prefix) + '.'
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else:
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# Use the database table as a column prefix if it wasn't given,
|
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# and if the requested column isn't a custom SELECT.
|
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if "." not in col_name and col_name not in (self._select or ()):
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table_prefix = qn(opts.db_table) + '.'
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else:
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table_prefix = ''
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order_by.append('%s%s %s' % (table_prefix, qn(orderfield2column(col_name, opts)), order))
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if order_by:
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sql.append("ORDER BY " + ", ".join(order_by))
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# Look for column name collisions in the select elements
|
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# and fix them with an AS alias. This allows us to do a
|
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# SELECT * later in the paging query.
|
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cols = [clause.split('.')[-1] for clause in select]
|
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for index, col in enumerate(cols):
|
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if cols.count(col) > 1:
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col = '%s%d' % (col.replace('"', ''), index)
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cols[index] = col
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select[index] = '%s AS %s' % (select[index], col)
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|
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# LIMIT and OFFSET clauses
|
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# To support limits and offsets, Oracle requires some funky rewriting of an otherwise normal looking query.
|
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select_clause = ",".join(select)
|
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distinct = (self._distinct and "DISTINCT " or "")
|
||||
|
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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)" % \
|
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(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)
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||||
else:
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||||
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 = {
|
||||
'exact': '= %s',
|
||||
'iexact': '= UPPER(%s)',
|
||||
|
||||
@@ -564,9 +564,9 @@ class _QuerySet(object):
|
||||
|
||||
return select, " ".join(sql), params
|
||||
|
||||
# Use the backend's QuerySet class if it defines one, otherwise use _QuerySet.
|
||||
if hasattr(backend, 'get_query_set_class'):
|
||||
QuerySet = backend.get_query_set_class(_QuerySet)
|
||||
# Use the backend's QuerySet class if it defines one. Otherwise, use _QuerySet.
|
||||
if connection.features.uses_custom_queryset:
|
||||
QuerySet = connection.ops.query_set_class(_QuerySet)
|
||||
else:
|
||||
QuerySet = _QuerySet
|
||||
|
||||
|
||||
Reference in New Issue
Block a user