How to sum 2 DecimalFields in a model and display in admin view?

user_16892182 0
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I have 2 DecimalFields in 1 model. How can I sum both fields together and have the total show up in the admin view?

price = models.DecimalField(max_digits=6, decimal_places=2)
spotters = models.DecimalField(max_digits=6, decimal_places=2, default=150)

There has to be a "container to retain the sum in admin view so I have:

total_price = models.DecimalField(max_digits=100, decimal_places=3, default=0)

At the end.

Then I finish with a return method:

def get_cost(self):
    return self.price + self.spotters

But its not working.

django-models django python
2 Answers

You can use the list display of ModelAdmin as stated in the documentation.

class MyModel(models.Model):
    ...
    def get_cost(self) -> int:
        return self.price + self.spotters

class MyModelAdmin(admin.ModelAdmin):
    list_display = ['get_cost']
user_27642060

I would advise to work with a property and without a total_price, since that only introduces data duplication, so:

class MyModel(models.Model):
    price = models.DecimalField(max_digits=6, decimal_places=2)
    spotters = models.DecimalField(max_digits=6, decimal_places=2, default=150)

    @property
    def total_price(self):
        return self.price + self.spotter

In the ModelAdmin, you can then add 'total_price' in the readonly_fields attribute [Django-doc]:

class MyModelAdmin(admin.ModelAdmin):
    list_display = ('price', 'spotters', 'total_price')
    fields = ('price', 'spotters')
    readonly_fields = ('total_price',)

admin.site.register(MyModel, MyModelAdmin)
user_675790
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