复制 Django Model 输入到另一个 Django 数据库

Question

I am trying to figure out if there was a way that once I uploaded something to one of my Django database files, that, that same upload would also upload to another database file, so if I go to delete one of them, it is saved in the other.

class CompanyInfo(models.Model):
  company_name = models.CharField("Company Name", unique=True, max_length=50, default="")

# Identifiers
identifier = models.IntegerField(default=0)



# Company Information
sector = models.CharField("Sector", max_length=50,default="")
location = models.CharField("Location", max_length=100, default="")
year_founded = models.IntegerField("Year Founded", default=2000)
company_description = models.TextField("Company Description", default="")
state_registered_in = models.CharField("State of Registration",  choices=states_list, max_length=2, default=2)
company_url = models.URLField("Company URL", max_length=200, default="", blank=True, null=True)
phone_number = models.CharField("Phone Number", max_length=20,default="")
company_logo_url = models.ImageField("Company Logo", upload_to=None, height_field=None, width_field=None, max_length=100, blank=True, null=True)
facebook = models.URLField("Facebook URL", max_length=200, default="", blank=True, null=True)
linkedin = models.URLField("Linkedin URL", max_length=200, default="", blank=True, null=True)
instagram = models.URLField("Instagram URL", max_length=200, default="", blank=True, null=True)
email = models.EmailField("Email Address", max_length=40,default="")




def __str__(self):
    return "{} from {}".format(self.company_name, self.location)

Basically, once these values are created for the "CompanyInfo" class, I want it to also upload itself into another Django class in the exact same way, so if I eventually delete the input in the "CompanyInfo" class, there will still be a saved version in the other created database.

Answer 1

There's a couple of options like overriding save or using a model manager, but the easiest and more testable method is to use a post_save signal: https://docs.djangoproject.com/en/dev/ref/signals/#post-save

This allows you to grab model instances that are saved and updated, but do note that when an .update() call is made, the signal is skipped which may be undesirable.

The way you can save to your backup database is by writing the signal to extract all fields and resave. I would avoid the update_fields since some devs will not use it (it helps with optimizing queries).

def save_to_backup(sender, instance, created: bool, using: str, **kwargs):
    if using == "default":
        # You don't want to continuously save/i.e. infinite loop
        return
    fields = instance._meta.get_all_field_names()
    sender.objects.using("backup_alias").save(**{field: instance._meta.get_field(field) for field in fields})