| import datetime |
| |
| from django.utils import tree |
| from django.utils.copycompat import deepcopy |
| |
| class ExpressionNode(tree.Node): |
| """ |
| Base class for all query expressions. |
| """ |
| # Arithmetic connectors |
| ADD = '+' |
| SUB = '-' |
| MUL = '*' |
| DIV = '/' |
| MOD = '%%' # This is a quoted % operator - it is quoted |
| # because it can be used in strings that also |
| # have parameter substitution. |
| |
| # Bitwise operators |
| AND = '&' |
| OR = '|' |
| |
| def __init__(self, children=None, connector=None, negated=False): |
| if children is not None and len(children) > 1 and connector is None: |
| raise TypeError('You have to specify a connector.') |
| super(ExpressionNode, self).__init__(children, connector, negated) |
| |
| def _combine(self, other, connector, reversed, node=None): |
| if isinstance(other, datetime.timedelta): |
| return DateModifierNode([self, other], connector) |
| |
| if reversed: |
| obj = ExpressionNode([other], connector) |
| obj.add(node or self, connector) |
| else: |
| obj = node or ExpressionNode([self], connector) |
| obj.add(other, connector) |
| return obj |
| |
| ################### |
| # VISITOR METHODS # |
| ################### |
| |
| def prepare(self, evaluator, query, allow_joins): |
| return evaluator.prepare_node(self, query, allow_joins) |
| |
| def evaluate(self, evaluator, qn, connection): |
| return evaluator.evaluate_node(self, qn, connection) |
| |
| ############# |
| # OPERATORS # |
| ############# |
| |
| def __add__(self, other): |
| return self._combine(other, self.ADD, False) |
| |
| def __sub__(self, other): |
| return self._combine(other, self.SUB, False) |
| |
| def __mul__(self, other): |
| return self._combine(other, self.MUL, False) |
| |
| def __div__(self, other): |
| return self._combine(other, self.DIV, False) |
| |
| def __mod__(self, other): |
| return self._combine(other, self.MOD, False) |
| |
| def __and__(self, other): |
| return self._combine(other, self.AND, False) |
| |
| def __or__(self, other): |
| return self._combine(other, self.OR, False) |
| |
| def __radd__(self, other): |
| return self._combine(other, self.ADD, True) |
| |
| def __rsub__(self, other): |
| return self._combine(other, self.SUB, True) |
| |
| def __rmul__(self, other): |
| return self._combine(other, self.MUL, True) |
| |
| def __rdiv__(self, other): |
| return self._combine(other, self.DIV, True) |
| |
| def __rmod__(self, other): |
| return self._combine(other, self.MOD, True) |
| |
| def __rand__(self, other): |
| return self._combine(other, self.AND, True) |
| |
| def __ror__(self, other): |
| return self._combine(other, self.OR, True) |
| |
| def prepare_database_save(self, unused): |
| return self |
| |
| class F(ExpressionNode): |
| """ |
| An expression representing the value of the given field. |
| """ |
| def __init__(self, name): |
| super(F, self).__init__(None, None, False) |
| self.name = name |
| |
| def __deepcopy__(self, memodict): |
| obj = super(F, self).__deepcopy__(memodict) |
| obj.name = self.name |
| return obj |
| |
| def prepare(self, evaluator, query, allow_joins): |
| return evaluator.prepare_leaf(self, query, allow_joins) |
| |
| def evaluate(self, evaluator, qn, connection): |
| return evaluator.evaluate_leaf(self, qn, connection) |
| |
| class DateModifierNode(ExpressionNode): |
| """ |
| Node that implements the following syntax: |
| filter(end_date__gt=F('start_date') + datetime.timedelta(days=3, seconds=200)) |
| |
| which translates into: |
| POSTGRES: |
| WHERE end_date > (start_date + INTERVAL '3 days 200 seconds') |
| |
| MYSQL: |
| WHERE end_date > (start_date + INTERVAL '3 0:0:200:0' DAY_MICROSECOND) |
| |
| ORACLE: |
| WHERE end_date > (start_date + INTERVAL '3 00:03:20.000000' DAY(1) TO SECOND(6)) |
| |
| SQLITE: |
| WHERE end_date > django_format_dtdelta(start_date, "+" "3", "200", "0") |
| (A custom function is used in order to preserve six digits of fractional |
| second information on sqlite, and to format both date and datetime values.) |
| |
| Note that microsecond comparisons are not well supported with MySQL, since |
| MySQL does not store microsecond information. |
| |
| Only adding and subtracting timedeltas is supported, attempts to use other |
| operations raise a TypeError. |
| """ |
| def __init__(self, children, connector, negated=False): |
| if len(children) != 2: |
| raise TypeError('Must specify a node and a timedelta.') |
| if not isinstance(children[1], datetime.timedelta): |
| raise TypeError('Second child must be a timedelta.') |
| if connector not in (self.ADD, self.SUB): |
| raise TypeError('Connector must be + or -, not %s' % connector) |
| super(DateModifierNode, self).__init__(children, connector, negated) |
| |
| def evaluate(self, evaluator, qn, connection): |
| return evaluator.evaluate_date_modifier_node(self, qn, connection) |