def get_initial_value(self, obj, **kwargs):

        values = []
        for source in self.sources:
            result = self.get_source_value(obj, source, **kwargs)

            for value in result:
                if isinstance(value, Model):
                    value = (value.pk, value)

                if value is not None:
                    if not isinstance(value, (tuple, list)):
                        value = (value, value)
                    values.append(value)

        if len(values) == 1:
            value = values[0]
            if value is None and self.empty_value is not None:
                value = self.empty_value
        elif len(values) > 0:
            plain_value = [v[0] for v in values]
            rich_value = self.separator.join(map(six.text_type, [v[1] for v in values]))
            value = (plain_value, rich_value)
        else:
            value = self.empty_value

        return value
Builds a list of values provided by :py:attr:`.sources` looked up on the target ``obj``.
dataset/ETHPy150Open pivotal-energy-solutions/django-datatable-view/datatableview/columns.py/Column.get_initial_value