python / expert
Snippet
Aggregated ValidationError Collection in Form Cleaning Pipelines
Illustrates advanced form validation techniques in Django by accumulating multiple ValidationErrors and raising them simultaneously.
snippet.py
python
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from django import formsfrom django.core.exceptions import ValidationErrorclass MultiStepValidationForm(forms.Form):payload = forms.CharField(widget=forms.Textarea)def clean(self):cleaned_data = super().clean()errors = []raw_payload = cleaned_data.get("payload", "")if not raw_payload.startswith("{"):errors.append(ValidationError("Payload must be valid JSON format.", code="invalid_format"))if len(raw_payload) > 1000:errors.append(ValidationError("Payload exceeds maximum length limit.", code="too_large"))if errors:raise ValidationError(errors)return cleaned_data
django
Breakdown
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class MultiStepValidationForm(forms.Form):
Defines a custom Django Form class with complex payload validation rules.
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def clean(self):
Overrides clean method to perform multi-field and structural validation checks.
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errors.append(ValidationError("Payload must be valid JSON format.", code="invalid_format"))
Appends discrete ValidationError instances with unique error codes to a collector list.
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raise ValidationError(errors)
Raises the collected list of errors simultaneously to display all issues at once.