--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/app/django/db/models/sql/where.py Fri Jul 18 18:22:23 2008 +0000
@@ -0,0 +1,171 @@
+"""
+Code to manage the creation and SQL rendering of 'where' constraints.
+"""
+import datetime
+
+from django.utils import tree
+from django.db import connection
+from django.db.models.fields import Field
+from django.db.models.query_utils import QueryWrapper
+from datastructures import EmptyResultSet, FullResultSet
+
+# Connection types
+AND = 'AND'
+OR = 'OR'
+
+class WhereNode(tree.Node):
+ """
+ Used to represent the SQL where-clause.
+
+ The class is tied to the Query class that created it (in order to create
+ the corret SQL).
+
+ The children in this tree are usually either Q-like objects or lists of
+ [table_alias, field_name, field_class, lookup_type, value]. However, a
+ child could also be any class with as_sql() and relabel_aliases() methods.
+ """
+ default = AND
+
+ def as_sql(self, node=None, qn=None):
+ """
+ Returns the SQL version of the where clause and the value to be
+ substituted in. Returns None, None if this node is empty.
+
+ If 'node' is provided, that is the root of the SQL generation
+ (generally not needed except by the internal implementation for
+ recursion).
+ """
+ if node is None:
+ node = self
+ if not qn:
+ qn = connection.ops.quote_name
+ if not node.children:
+ return None, []
+ result = []
+ result_params = []
+ empty = True
+ for child in node.children:
+ try:
+ if hasattr(child, 'as_sql'):
+ sql, params = child.as_sql(qn=qn)
+ format = '(%s)'
+ elif isinstance(child, tree.Node):
+ sql, params = self.as_sql(child, qn)
+ if child.negated:
+ format = 'NOT (%s)'
+ elif len(child.children) == 1:
+ format = '%s'
+ else:
+ format = '(%s)'
+ else:
+ sql, params = self.make_atom(child, qn)
+ format = '%s'
+ except EmptyResultSet:
+ if node.connector == AND and not node.negated:
+ # We can bail out early in this particular case (only).
+ raise
+ elif node.negated:
+ empty = False
+ continue
+ except FullResultSet:
+ if self.connector == OR:
+ if node.negated:
+ empty = True
+ break
+ # We match everything. No need for any constraints.
+ return '', []
+ if node.negated:
+ empty = True
+ continue
+ empty = False
+ if sql:
+ result.append(format % sql)
+ result_params.extend(params)
+ if empty:
+ raise EmptyResultSet
+ conn = ' %s ' % node.connector
+ return conn.join(result), result_params
+
+ def make_atom(self, child, qn):
+ """
+ Turn a tuple (table_alias, field_name, field_class, lookup_type, value)
+ into valid SQL.
+
+ Returns the string for the SQL fragment and the parameters to use for
+ it.
+ """
+ table_alias, name, field, lookup_type, value = child
+ if table_alias:
+ lhs = '%s.%s' % (qn(table_alias), qn(name))
+ else:
+ lhs = qn(name)
+ db_type = field and field.db_type() or None
+ field_sql = connection.ops.field_cast_sql(db_type) % lhs
+
+ if isinstance(value, datetime.datetime):
+ cast_sql = connection.ops.datetime_cast_sql()
+ else:
+ cast_sql = '%s'
+
+ if field:
+ params = field.get_db_prep_lookup(lookup_type, value)
+ else:
+ params = Field().get_db_prep_lookup(lookup_type, value)
+ if isinstance(params, QueryWrapper):
+ extra, params = params.data
+ else:
+ extra = ''
+
+ if lookup_type in connection.operators:
+ format = "%s %%s %s" % (connection.ops.lookup_cast(lookup_type),
+ extra)
+ return (format % (field_sql,
+ connection.operators[lookup_type] % cast_sql), params)
+
+ if lookup_type == 'in':
+ if not value:
+ raise EmptyResultSet
+ if extra:
+ return ('%s IN %s' % (field_sql, extra), params)
+ return ('%s IN (%s)' % (field_sql, ', '.join(['%s'] * len(value))),
+ params)
+ elif lookup_type in ('range', 'year'):
+ return ('%s BETWEEN %%s and %%s' % field_sql, params)
+ elif lookup_type in ('month', 'day'):
+ return ('%s = %%s' % connection.ops.date_extract_sql(lookup_type,
+ field_sql), params)
+ elif lookup_type == 'isnull':
+ return ('%s IS %sNULL' % (field_sql, (not value and 'NOT ' or '')),
+ params)
+ elif lookup_type == 'search':
+ return (connection.ops.fulltext_search_sql(field_sql), params)
+ elif lookup_type in ('regex', 'iregex'):
+ return connection.ops.regex_lookup(lookup_type) % (field_sql, cast_sql), params
+
+ raise TypeError('Invalid lookup_type: %r' % lookup_type)
+
+ def relabel_aliases(self, change_map, node=None):
+ """
+ Relabels the alias values of any children. 'change_map' is a dictionary
+ mapping old (current) alias values to the new values.
+ """
+ if not node:
+ node = self
+ for pos, child in enumerate(node.children):
+ if hasattr(child, 'relabel_aliases'):
+ child.relabel_aliases(change_map)
+ elif isinstance(child, tree.Node):
+ self.relabel_aliases(change_map, child)
+ else:
+ if child[0] in change_map:
+ node.children[pos] = (change_map[child[0]],) + child[1:]
+
+class EverythingNode(object):
+ """
+ A node that matches everything.
+ """
+ def as_sql(self, qn=None):
+ raise FullResultSet
+
+ def relabel_aliases(self, change_map, node=None):
+ return