How can i convert string to int and then sort view by int value?-CodePudding

I want sort view by a value that is string. but before that, i want convert string to int then sort by that.

main = models.Main.objects.all().order_by('fore_key__n')

In this code fore_key__n is string value like '20'

CodePudding user response：

Annotations and DB functions can probably do this. Cast the string value to an int and then use it to order the queryset. I haven't ever had cause to try this, so treat the following as a suggestion:

 main = models.Main.objects.annotate(
   fkn_int_cast=Cast('fore_key__n', output_field=IntegerField()),
 ).order_by('fkn_int_cast')

It will throw a django.db.utils.DataError should the data in the field not be capable of conversion. Therefore, it's probably necessary to apply a regex filter as well

 main = models.Main.objects.filter(
   fore_key_n__regex='^[0-9] $'
 ).annotate(
   fkn_int_cast=Cast('fore_key__n', output_field=IntegerField()),
 ).order_by('fkn_int_cast')

There are other DB functions you might use, for example, to replace the commas in '1,234,456' with null strings so it becomes Cast'able