django-table2 and django annotate issue - django-tables2

Question

I have a use case in django_tables2 with django.db.models Sum, but can not figure out the usage after reading django doc with aggregation, I am wondering whether that is possible:
# models.py
class AModel(models.Model):
a_id = models.IntegerField()
a_name = models.CharField(max_length=50)
def __unicode__(self):
return unicode(self.name)
class BModel(models.Model):
b_id = models.IntegerField()
b_name = models.CharField(max_length=50)
a_name = models.ForeignKey(AModel)
def __unicode__(self):
return self.b_name
class CModel(models.Model):
c_id = models.IntegerField()
c_name = models.CharField(max_length=50)
c_status = models.CharField(max_length=8)
def __unicode__(self):
return self.c_name
class DModel(models.Model):
d_id = models.IntegerField()
dmode = models.CharField(max_length=50)
bmodel = models.ForeignKey(BModel)
cmodel = models.ForeignKey(CModel)
date = models.DateField(null=True)
cost = models.FloatField(default=0.00)
def __unicode__(self):
return self.d_name
# tables.py
import django_tables2 as tables
class DmodelTable(tables.Table)
class Meta:
model = DModel
fields = ('dmodel', 'bmodel', 'cmodel', 'cost')
class TargetTable(tables.Table)
a_name = tables.Column(accessor='b_name.a_name')
class Meta:
model = DModel
fields = ('bmodel', 'cmodel', 'amodel', 'cost_sum')
# view.py
from django.db.models import Sum
...
def page(request):
queryset = DModel.objects.values('bmodel','cmodel').annotate(cost_sum=Sum('cost'))
table = TargetTable(queryset)
return render(request, 'tartget.html', {'table':table})
def dmodelpage(request):
table = DModelTable(DModel.objects.all())
return render(request, 'tartget.html', {'table':table})
the result I got is as following is the TargetTable:
+---------+------------+----------+--------------------+
| b_name | c_name | a_name | cost_sum |
+---------+------------+----------+--------------------+
| 1863703 | 8485748 | - | 3150 |
| 1863703 | 8688288 | - | 0 |
| 1863703 | 8691184 | - | 712.5 |
I encounter 2 problems with the solution:
The b_name and c_name are ids, not the name as expected.
a_name is null, I think because the first issue, that the bmodel is not correctly return bmodel in queryset, then the bmodel.a_name dose not work.
I can find solution for display "id" issue for only one ForeignKey in DModel, like mentioned here, but have no idea how to deal with mutlti-foreign key cases.
Can someone help? Thanks very much

Answer 1

You might need to define a __str__/__unicode__ method on your models returning self.x_name.
The name of your foreign key on DModel is b_name, so you should use a_name = tables.Column(accessor='b_name.b_name')

Answer 2

all, later I figure out the issues:
# table.py
class TargetTable(tables.Table)
class Meta:
model = DModel
fields = ('bmodel__b_name', 'cmodel__c_name', 'cmodel__amodel__a_name', 'cost_sum')
# view.py
from django.db.models import Sum
...
def page(request):
queryset = DModel.objects.values('bmodel__b_name','cmode__c_name', 'cmode__amode__a_name').annotate(cost_sum=Sum('cost'))
table = TargetTable(queryset)
return render(request, 'tartget.html', {'table':table})
If you want show name, then should refer to the exactly field name of that model. And all the aggragation columns that need must be added in the .values().