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How would I access the instance of the model that is being validated from within the validator for a specific field?
models.py
def question_instances(value): #validator
# not sure how to get model instance within this function
industry = model_instance.industry
questions = Question.objects.filter(industry=industry)
if questions.count() > 3:
raise ValidationError('Too many questions for this industry')
class ExampleQuestion(models.Model):
industry = models.ForeignKey(Industry, on_delete=models.CASCADE)
question = models.CharField(max_length=200, validators=[question_instances])
def __str__(self):
return self.industry.industryname
948
A validator is a function that takes in the fields new value, and then acts on it. They are a simple way to customize a field. They allow you to trigger functionality when a field's value changes, modify input, or limit which values are acceptable.
Django provides built-in methods to validate form data automatically. Django forms submit only if it contains CSRF tokens. It uses uses a clean and easy approach to validate data. The is_valid() method is used to perform validation for each field of the form, it is defined in Django Form class.
A model is the single, definitive source of information about your data. It contains the essential fields and behaviors of the data you're storing. Generally, each model maps to a single database table. The basics: Each model is a Python class that subclasses django.db.models.Model .
create() will automatically save, so even if you fix your error - you will still have to make sure the arguments to create fulfill the database requirements to save a record.
You can't. If you need this, don't use a validator; use a clean function instead.
class ExampleQuestion(models.Model):
industry = models.ForeignKey(Industry, on_delete=models.CASCADE)
question = models.CharField(max_length=200)
def clean(self):
industry = self.industry
questions = Question.objects.filter(industry=industry).exclude(pk=self.pk)
if questions.count() > 3:
raise ValidationError('Too many questions for this industry')
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