Ordering by custom field raises an error

[deltadanger]

When defining a custom field in a table, as name = tables.Column() with methods to render and order render_name and order_name, sorting by this column causes an error if the custom field is not in last position:

• Viewing /mytable?sort=name works
• Viewing /mytable?sort=email&sort=name works
• Viewing /mytable?sort=name&sort=email raises a FieldError "Cannot resolve keyword u'name' into field"

The cause of this problem is at https://github.com/bradleyayers/django-tables2/blob/master/django_tables2/tables.py#L108, this code is only called for the last column, whereas it should be checked for all columns.

[jieter]

Thanks for the bug report, it seems you did look into it a bit, can you maybe provide a test to reproduce the problem reliably? And maybe also a fix?

[deltadanger]

Here is a simple test configuration to reproduce the problem:

models.py:

class Person(models.Model):
    first_name = models.CharField(max_length=50)
    last_name = models.CharField(max_length=50)

tables.py:

class PersonTable(tables.Table):
    first_name = tables.Column()
    last_name = tables.Column()
    full_name = tables.Column()

    def render_full_name(self, record):
        return record.last_name + ' ' + record.first_name

    def order_full_name(self, queryset, is_descending):
        queryset = queryset.annotate(
            full_name=Concat(F('last_name'), Value(' '), F('first_name'))
        ).order_by(('-' if is_descending else '') + 'full_name')
        return queryset, True

    class Meta:
        model = Person
        fields = (
            'first_name',
            'last_name',
            'full_name',
        )

tests.py:

class PersonTestCase(TestCase):
    def setUp(self):
        self.factory = RequestFactory()

        Person.objects.create(first_name="Alice", last_name='Beta')
        Person.objects.create(first_name="Bob", last_name='Alpha')

    def test_ordering_by_name(self):
        request = self.factory.get('/?sort=first_name')
        table = PersonTable(Person.objects.all())
        RequestConfig(request, paginate=False).configure(table)

        self.assertEqual(table.rows[0].record.first_name, 'Alice')

    def test_ordering_by_custom_field(self):
        request = self.factory.get('/?sort=full_name')
        table = PersonTable(Person.objects.all())
        RequestConfig(request, paginate=False).configure(table)

        self.assertEqual(table.rows[0].record.first_name, 'Bob')

    def test_ordering_by_both_with_custom_last(self):
        request = self.factory.get('/?sort=first_name&sort=full_name')
        table = PersonTable(Person.objects.all())
        RequestConfig(request, paginate=False).configure(table)

        self.assertEqual(table.rows[0].record.first_name, 'Bob')

    def test_ordering_by_both_with_custom_first(self):
        request = self.factory.get('/?sort=full_name&sort=first_name')
        table = PersonTable(Person.objects.all())
        RequestConfig(request, paginate=False).configure(table)

        self.assertEqual(table.rows[0].record.first_name, 'Bob')

The test test_ordering_by_both_with_custom_first raises a FieldError.

Changing the order_by function to the following fixes the problem:

    def order_by(self, aliases):
        '''
        Order the data based on order by aliases (prefixed column names) in the
        table.

        Arguments:
            aliases (`~.utils.OrderByTuple`): optionally prefixed names of
                columns ('-' indicates descending order) in order of
                significance with regard to data ordering.
        '''
        bound_column = None
        modified_by_custom_order = False
        accessors = []
        for alias in aliases:
            bound_column = self.table.columns[OrderBy(alias).bare]
            # bound_column.order_by reflects the current ordering applied to
            # the table. As such we need to check the current ordering on the
            # column and use the opposite if it doesn't match the alias prefix.
            if alias[0] != bound_column.order_by_alias[0]:
                accessors += bound_column.order_by.opposite
            else:
                accessors += bound_column.order_by

            if hasattr(self, 'queryset') and bound_column:
                # Custom ordering
                self.queryset, modified = bound_column.order(self.queryset, alias[0] == '-')
                modified_by_custom_order = modified_by_custom_order or modified

        if modified_by_custom_order:
            return

        # Traditional ordering
        if accessors:
            order_by_accessors = (a.for_queryset() for a in accessors)
            self.queryset = self.queryset.order_by(*order_by_accessors)
        else:
            self.list.sort(key=OrderByTuple(accessors).key)

[jieter]

@tjacoel thanks for your example.

Your fix however, doesn't pass some of the other unit tests with the error AttributeError: 'TableData' object has no attribute 'queryset'

[jieter]

released 1.4.0