Custom columns in django_tables2

Question

I've had a search around for this but haven't had much luck so looking for a bit of help. I'm trying to add some extra columns to a table defined by a model, using function definitions in the model. Here's what my code looks like now:

# models.py
class MyModel(models.Model):
    my_field = models.TextField()

    def my_function(self):
        # Return some calculated value based on the entry
        return my_value

# tables.py
class MyTable(tables.Table):

    my_extra_column = tables.Column(....)

    class Meta:
        model = MyModel

# views.py
table = MyTable(MyModel.objects.all())
RequestConfig(request).configure(table)
return render(request, ....)

My question is can I access my_function in the entries passed to MyTable so I can show the result of my_function in the custom my_extra_column column? I assume I need to be using accessors, but I can't see how I can access the queryset data using this. Thanks!

Answer 1

I figured it out in the end, it was actually not too hard after all :) So using my example above, in order to add a custom column using a function in the associated model you just use accessors ...

# models.py
class MyModel(models.Model):
    my_field = models.TextField()
    my_field_2 = models.IntegerField()

    def my_function(self):
        # Return some calculated value based on the entry
        return my_value

# tables.py
class MyTable(tables.Table):

    my_extra_column = tables.Column(accessor='my_function',
         verbose_name='My calculated value')

    class Meta:
        fields = ['my_field', 'my_field_2', 'my_extra_column']
        model = MyModel

The trouble comes if and when you want to be able to sort this data, because the function won't translate into any valid field in MyModel. So you could either disable sorting on this column using ordering=False or specify a set using order_by=('field', 'field2')