Ticket #10154: dateexpressions.diff

django/db/models/expressions.py

@@ -1 +1 @@
 from copy import deepcopy
-from datetime import datetime
+import datetime
+from django.db import connection
 
 from django.utils import tree
 
@@ -26 +27 @@
         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)
@@ -108 +112 @@
 
     def evaluate(self, evaluator, qn):
         return evaluator.evaluate_leaf(self, qn)
+
+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:
+        SQLITE:
+            where end_date > date(start_date, "3 days 200 seconds")
+
+        POSTGRES:
+            where end_date > (start_date + interval '3 days 200 seconds')
+
+    """
+    def __init__(self, children, connector=None, negated=False):
+        if len(children) != 2:
+            raise TypeError('You have to specify a node and a timedelta.')
+        if connector is None:
+            raise TypeError('You have to specify a connector.')
+        super(DateModifierNode, self).__init__([children[0], DateModifierLeaf(children[1])], connector, negated)
+
+    def prepare(self, evaluator, query, allow_joins):
+        return evaluator.prepare_node(self, query, allow_joins)
+
+    def evaluate(self, evaluator, qn):
+        if not qn:
+            qn = connection.ops.quote_name
+
+        modifiers = self.children.pop().evaluate(evaluator, qn)
+        sql, params = evaluator.evaluate_node(self, qn)
+
+        return connection.ops.date_interval_sql(sql, self.connector, modifiers), params
+
+class DateModifierLeaf(object):
+    def __init__(self, timedelta):
+        self.days = timedelta.days
+        self.seconds = timedelta.seconds
+
+    def prepare(self, evaluator, query, allow_joins):
+        pass
+
+    def evaluate(self, evaluator, qn):
+        # move exact representation to backend ?
+        mods = []
+        if self.days:
+            mods.append(u'%s days' % self.days)
+        if self.seconds:
+            mods.append(u'%s seconds' % self.seconds)
+        return mods

django/db/backends/postgresql/operations.py

@@ -28 +28 @@
         # http://www.postgresql.org/docs/8.0/static/functions-datetime.html#FUNCTIONS-DATETIME-EXTRACT
         return "EXTRACT('%s' FROM %s)" % (lookup_type, field_name)
 
+    def date_interval_sql(self, sql, connector, modifiers):
+        # implements the interval functionality for expressions
+        mods = u' '.join([u'%s' % modifier for modifier in modifiers])
+        conn = u' %s ' % connector
+        return u'(%s)' % conn.join([sql, u'interval \'%s\'' % mods])
+
     def date_trunc_sql(self, lookup_type, field_name):
         # http://www.postgresql.org/docs/8.0/static/functions-datetime.html#FUNCTIONS-DATETIME-TRUNC
         return "DATE_TRUNC('%s', %s)" % (lookup_type, field_name)

django/db/backends/__init__.py

@@ -104 +104 @@
         """
         raise NotImplementedError()
 
+    def date_interval_sql(self, sql, connector, modifiers):
+        """
+        Implements the interval functionality for expressions
+        """
+        mods = u','.join([u'"%s%s"' % (connector, modifier) for modifier in modifiers])
+        return u'DATE(%s, %s)' % (sql, mods)
+
     def date_trunc_sql(self, lookup_type, field_name):
         """
         Given a lookup_type of 'year', 'month' or 'day', returns the SQL that

tests/modeltests/expressions/models.py

@@ -7 +7 @@
 class Employee(models.Model):
     firstname = models.CharField(max_length=50)
     lastname = models.CharField(max_length=50)
+    contract_date = models.DateField(null=True)
+    start_date = models.DateField(null=True)
 
     def __unicode__(self):
         return u'%s %s' % (self.firstname, self.lastname)
@@ -30 +32 @@
 __test__ = {'API_TESTS': """
 >>> from django.db.models import F
 
+>>> import datetime
+
 >>> Company(name='Example Inc.', num_employees=2300, num_chairs=5,
-...     ceo=Employee.objects.create(firstname='Joe', lastname='Smith')).save()
+...     ceo=Employee.objects.create(firstname='Joe', lastname='Smith',
+...     contract_date=datetime.date(2008,1,1), start_date=datetime.date(2008,3,1))).save()
 >>> Company(name='Foobar Ltd.', num_employees=3, num_chairs=3,
-...     ceo=Employee.objects.create(firstname='Frank', lastname='Meyer')).save()
+...     ceo=Employee.objects.create(firstname='Frank', lastname='Meyer',
+...     contract_date=datetime.date(2008,1,1), start_date=datetime.date(2008,5,1))).save()
 >>> Company(name='Test GmbH', num_employees=32, num_chairs=1,
-...     ceo=Employee.objects.create(firstname='Max', lastname='Mustermann')).save()
+...     ceo=Employee.objects.create(firstname='Max', lastname='Mustermann',
+...     contract_date=datetime.date(2008,1,1), start_date=datetime.date(2008,7,1))).save()
 
 # We can filter for companies where the number of employees is greater than the
 # number of chairs.
@@ -68 +75 @@
 ...
 FieldError: Joined field references are not permitted in this query
 
+# F expressions for dates may be combined with timedelta
+
+>>> Employee.objects.filter(start_date__gt=F('contract_date')+datetime.timedelta(days=80, seconds=500))
+[<Employee: Frank Meyer>, <Employee: Max Mustermann>]
+
+>>> Employee.objects.filter(contract_date__gt=F('start_date')-datetime.timedelta(days=80, seconds=500))
+[<Employee: Joe Smith>]
+
 """}