Trying to insert a new column with a list of foreign field in django_tables2

Question

I'm using the django_tables2 to show a list of "repair details". So far so good. However I want to add a new field (it's not in the model): a list of service reports. The relation is 1 to many. and show the serial number which is in another model. It's quite difficult since I add the field but the render_NEW_FIELD doesn't work and i couldn't reach the list of service reports since in the table model I have just access to the record and not to the repair_detail model. I'm using django_tables 0.15

repair/models.py

class RepairDetail(models.Model):
    repair = models.ForeignKey('Repair')
    repair_detail_number = models.IntegerField()
    article_code = models.CharField(max_length=30)
    registered_date = models.DateField(null=True)
    registered_uid = models.IntegerField(null=True)
    registered_initials = models.CharField(max_length=2, null=True)
    customer_reference = models.CharField(max_length=20, null=True)
    db2_recnum = models.IntegerField()

    def __unicode__(self):
        return str(self.repair_detail_number)


class ServiceReport(models.Model):
    repair_detail = models.ForeignKey('RepairDetail')
    status = models.ForeignKey('ServiceReportStatus', on_delete=models.PROTECT)
    serial_number = models.ForeignKey('core.SerialNumber')
    customer = models.ForeignKey('core.Company')
    contact = models.ForeignKey('core.Contact', null=True, on_delete=models.SET_NULL)
    project = models.ForeignKey('core.Project')
    project_code = models.CharField(max_length=4)
    identifier = models.CharField(max_length=1)
    repair_date = models.DateField(null=True)
    repair_uid = models.IntegerField(null=True)
    repair_initials = models.CharField(max_length=2, null=True)
    booking_date = models.DateField(null=True)

core/models.py

class SerialNumber(models.Model):
    product = models.ForeignKey("Product")
    panel = models.ForeignKey("Panel", null=True, blank=True, default = None)
    serial_number = models.CharField(max_length=30, default='')
    manifest = models.TextField(null=True)

    def __unicode__(self):
        return self.serial_number

repair/tables.py

class RepairDetailTable(tables.Table):
    #serials = tables.Column(accessor='servicereport.serialnumber.serialnumber')
    serial = tables.Column()

    def __init__(self, *args, **kwargs):
        super(RepairDetailTable, self).__init__(*args, **kwargs)

    class Meta(object):
        model = RepairDetail
        fields = ('id', 'repair_detail_number', 'article_code', 'registered_date', 'registered_initials', 'customer_reference', 'serials')
        attrs = {'class': 'table table-striped table-bordered protonic'}
        empty_text = "No records found."

Answer 1

If you want (1:N instead of N:1) to concatenate all related models in the table cell try to do this in your model layer by setting property, something like this:

class RepairDetail(models.Model):
    # ...

    @property
    def service_reports_list(self):
        return self.servicereport_set.all()

Define your own column (inherit tables.Column) and override render method

Add it to your table class:

class RepairDetailTable(tables.Table):
    # ...
    service_reports_list = YourOwnColumn(some_kwargs)
    # ...