How to autofill a field with concatenated other fields Django

Question

This is the first time that I ask a question here, so sorry if it's not perfect.

I'm working in django on the last version.

I would like to auto-generate a field (KEY (which will be used in dialogflow)) value when I submit my form with the concatenation of other fields as

KEY =  'SENT_' + search_categories + '_' + '001'

and I would like that the '001' will be auto-incremented too.

I can't show more code because I'm not sure that it's legal cause I'm working in a private firm but I think that I can show the key declaration in my django model.

key = models.CharField(max_length=30, blank=False, null=False, unique=True)

I hope that you'll help me!

Thank you very much!

Answer 1

You can generate your key in the save function of your model :

class Model(models.model):
    key = models.CharField(max_length=30, blank=False, null=False, unique=True)
    # other attributes...

    def save(self, *args, **kwargs):
        # Only generate key on creating if it was not provided
        if not self.id and not self.key:
            # Get your counter and increment it
            counter = 0
            counter += 1
            # Get search_categories (I don't know what it is)
            search_categories = '?'
            # Use f-string to concatenate the key and add zero pad on the counter
            self.key = f'SENT_{search_categories}_{counter:03}'
        super().save(*args, **kwargs)