Ticket #26617: 26617.patch

django/contrib/postgres/aggregates/general.py

@@ -32 +32 @@
 
 class StringAgg(Aggregate):
     function = 'STRING_AGG'
-    template = "%(function)s(%(expressions)s, '%(delimiter)s')"
+    template = "%(function)s(%(distinct)s%(expressions)s, '%(delimiter)s')"
 
-    def __init__(self, expression, delimiter, **extra):
-        super(StringAgg, self).__init__(expression, delimiter=delimiter, **extra)
+    def __init__(self, expression, delimiter, distinct=False, **extra):
+        distinct = 'DISTINCT ' if distinct else ''
+        super(StringAgg, self).__init__(expression, delimiter=delimiter, distinct=distinct, **extra)
 
     def convert_value(self, value, expression, connection, context):
         if not value:

docs/ref/contrib/postgres/aggregates.txt

@@ -63 +63 @@
 ``StringAgg``
 -------------
 
-.. class:: StringAgg(expression, delimiter)
+.. class:: StringAgg(expression, delimiter, distinct=False)
 
     Returns the input values concatenated into a string, separated by
     the ``delimiter`` string.
@@ -72 +72 @@
 
         Required argument. Needs to be a string.
 
+    .. attribute:: distinct
+
+        .. versionadded: 1.10
+
+        This is a optional boolean argument.
+
+        If ``True``, a concatenated values will be distinct.
+        Default is ``False``.
+
 Aggregate functions for statistics
 ==================================
 

tests/postgres_tests/test_aggregates.py

@@ -110 +110 @@
         values = AggregateTestModel.objects.aggregate(stringagg=StringAgg('char_field', delimiter=';'))
         self.assertEqual(values, {'stringagg': ''})
 
+    def test_string_agg_distinct_false(self):
+        AggregateTestModel.objects.all().delete()
+        AggregateTestModel.objects.create(char_field='Foo')
+        AggregateTestModel.objects.create(char_field='Foo')
+        AggregateTestModel.objects.create(char_field='Bar')
+        models = AggregateTestModel.objects.order_by('char_field')
+        values = models.aggregate(stringagg=StringAgg('char_field', delimiter=' ', distinct=False))
+        aggregates = values['stringagg']
+        self.assertEqual(aggregates.count('Foo'), 2)
+        self.assertEqual(aggregates.count('Bar'), 1)
+
+    def test_string_agg_distinct_true(self):
+        AggregateTestModel.objects.all().delete()
+        AggregateTestModel.objects.create(char_field='Foo')
+        AggregateTestModel.objects.create(char_field='Foo')
+        AggregateTestModel.objects.create(char_field='Bar')
+        models = AggregateTestModel.objects.order_by('char_field')
+        values = models.aggregate(stringagg=StringAgg('char_field', delimiter=' ', distinct=True))
+        aggregates = values['stringagg']
+        self.assertEqual(aggregates.count('Foo'), 1)
+        self.assertEqual(aggregates.count('Bar'), 1)
+
 
 class TestStatisticsAggregate(PostgreSQLTestCase):
     @classmethod