Review the following Django form handling code designed for a college application and test submission process. The code manages the collection and validation of applicant information, including personal details, academic records, and standardized test scores. Identify any bugs, inefficiencies, security risks, or deviations from Django best practices and PEP 8 standards.
from django import forms
from django.core.exceptions import ValidationError
from college.models import Application, AcademicRecord, TestScore
from django.utils.translation import gettext_lazy as _
from django.db import transaction
class CollegeApplicationForm(forms.ModelForm):
class Meta:
model = Application
fields = ['first_name', 'last_name', 'email', 'phone_number', 'address', 'birthdate', 'intended_major']
gpa = forms.DecimalField(max_digits=4, decimal_places=2, min_value=0.0, max_value=4.0)
sat_score = forms.IntegerField(min_value=400, max_value=1600, required=False)
act_score = forms.IntegerField(min_value=1, max_value=36, required=False)
transcript = forms.FileField(required=True)
def clean(self):
cleaned_data = super().clean()
sat_score = cleaned_data.get('sat_score')
act_score = cleaned_data.get('act_score')
if not sat_score and not act_score:
raise ValidationError(_('At least one test score (SAT or ACT) is required.'))
if cleaned_data.get('emai') and Application.objects.filter(email=cleaned_data.get('email')).exists():
raise ValidationError(_('An application with this email already exists.'))
return cleaned_data
def save(self, commit=True):
with transaction.atomic():
application = super().save(commit=False)
academic_record = AcademicRecord(
application=application,
gpa=self.cleaned_data['gpa'],
transcript=self.cleaned_data['transcript']
)
if commit:
application.save()
academic_record.save()
if self.cleaned_data.get('sat_score'):
TestScore.objects.create(
application=application,
test_type='SAT',
score=self.cleaned_data['sat_score']
)
if self.cleaned_data.get('act_score'):
TestScore.objects.create(
application=application,
test_type='ACT',
score=self.cleaned_data['act_score']
)
return application
Response
Of course. Here is a detailed review of the provided Django form handling code, broken down by category.
Summary of Findings
The code attempts to handle a complex object creation process within a single form, which is a valid but advanced pattern. However, it contains several critical bugs that will cause it to fail or behave incorrectly, a significant data integrity risk, and several deviations from Django best practices and PEP 8 standards.
1. Critical Bugs
These are issues that will cause runtime errors or prevent the code from working as intended.
Bug 1: Typo in clean() Method
In the clean() method, the email uniqueness check has a typo.
- Code:
if cleaned_data.get('emai') ...
- Problem: It checks for the key
'emai' instead of 'email'. Because cleaned_data.get('emai') will always return None, this uniqueness check will never run, allowing duplicate applications to be submitted.
- Fix: Correct the typo from
emai to email.
The save() method does not correctly respect the commit=False argument.
- Code: The
TestScore.objects.create(...) calls are outside the if commit: block.
- Problem: If the form is saved with
form.save(commit=False), the Application and AcademicRecord instances are correctly held in memory without being saved to the database. However, the TestScore objects will be created and saved to the database immediately, violating the purpose of commit=False and leaving orphaned TestScore records if the parent application is never saved.
- Fix: All database-writing operations must be moved inside the
if commit: block.
The order of operations in the save() method is incorrect.
- Code:
python
application = super().save(commit=False)
academic_record = AcademicRecord(application=application, ...)
# ...
if commit:
application.save()
academic_record.save()
- Problem:
academic_record is instantiated with an application object that has not yet been saved to the database (it has no primary key). When academic_record.save() is called, it will fail with an IntegrityError because the foreign key to Application (application_id) will be NULL.
- Fix: The parent
application object must be saved before any child objects that reference it are saved.
2. Security & Data Integrity Risks
Risk 1: Race Condition in Email Uniqueness Check
Even with the typo fixed, the manual uniqueness check in the clean() method is vulnerable to a race condition.
- Problem: Two users could submit a form with the same email at nearly the same time. Both forms could pass the
clean() method's check (Application.objects.filter(...).exists()) before either is saved. The first to hit the database will save successfully, but the second will raise an IntegrityError, resulting in an unhandled server error (500) instead of a clean validation message to the user.
- Best Practice: The canonical way to enforce uniqueness in Django is at the model level. The
email field on the Application model should be defined with unique=True.
python
# In college/models.py
class Application(models.Model):
email = models.EmailField(unique=True)
# ... other fields
ModelForm validation will automatically handle this check correctly and without race conditions. The manual check in clean() should be removed.
3. Inefficiencies & Django Best Practices
The form defines fields (gpa, sat_score, etc.) that are not on the Application model.
- Observation: This is a valid pattern for handling related models, but it's important to be explicit about it. The current structure works, but it can be confusing. The fields are correctly defined at the class level, as they are not part of the
Meta model's fields.
- Best Practice: The implementation is acceptable, but the
save() method, which orchestrates the creation of these related models, must be flawless. The use of transaction.atomic() is an excellent practice here, but its benefits are negated by the bugs within the save method.
Issue 2: Multiple Database Hits in save()
The save() method creates TestScore objects with separate TestScore.objects.create() calls.
- Problem: This results in two separate
INSERT queries to the database. While not a major issue for only two objects, it's less efficient than creating them in a single query.
- Best Practice: For creating multiple objects of the same type, use
bulk_create(). This sends a single, more efficient query to the database.
4. PEP 8 & Code Style
- Missing Docstrings: The form class
CollegeApplicationForm lacks a docstring explaining its purpose.
- Vertical Spacing: There should be a blank line between the
Meta class and the field definitions for better readability.
Corrected and Refactored Code
Here is the revised code that addresses all the identified issues.
from django import forms
from django.core.exceptions import ValidationError
from college.models import Application, AcademicRecord, TestScore
from django.utils.translation import gettext_lazy as _
from django.db import transaction
class CollegeApplicationForm(forms.ModelForm):
"""
A form for handling college applications, including academic records
and standardized test scores.
This form creates an Application instance and its related AcademicRecord
and TestScore objects in a single atomic transaction.
"""
# Fields for related models (AcademicRecord and TestScore)
gpa = forms.DecimalField(max_digits=3, decimal_places=2, min_value=0.0, max_value=4.0)
transcript = forms.FileField(required=True)
sat_score = forms.IntegerField(min_value=400, max_value=1600, required=False)
act_score = forms.IntegerField(min_value=1, max_value=36, required=False)
class Meta:
model = Application
fields = [
'first_name', 'last_name', 'email', 'phone_number',
'address', 'birthdate', 'intended_major'
]
# Note: It's assumed that Application.email has `unique=True`
# which makes the manual uniqueness check in clean() redundant and unsafe.
def clean(self):
"""
Ensure that at least one standardized test score is provided.
"""
cleaned_data = super().clean()
sat_score = cleaned_data.get('sat_score')
act_score = cleaned_data.get('act_score')
if not sat_score and not act_score:
# This attaches the error to a specific field for better UX
self.add_error('sat_score', _('At least one test score (SAT or ACT) is required.'))
# Alternatively, for a non-field error at the top of the form:
# raise ValidationError(_('At least one test score (SAT or ACT) is required.'))
return cleaned_data
def save(self, commit=True):
"""
Saves the Application and its related models.
If commit=True, this method saves the application, academic record,
and any provided test scores to the database within a single transaction.
"""
# Create the Application instance in memory but don't save it yet.
# This allows us to work with the object before committing to the DB.
application = super().save(commit=False)
if commit:
# Use a transaction to ensure all or no objects are created.
with transaction.atomic():
# 1. Save the parent object first to get a primary key.
application.save()
# 2. Create and save the related AcademicRecord.
AcademicRecord.objects.create(
application=application,
gpa=self.cleaned_data['gpa'],
transcript=self.cleaned_data['transcript']
)
# 3. Prepare TestScore objects for bulk creation.
test_scores_to_create = []
if self.cleaned_data.get('sat_score'):
test_scores_to_create.append(
TestScore(
application=application,
test_type='SAT',
score=self.cleaned_data['sat_score']
)
)
if self.cleaned_data.get('act_score'):
test_scores_to_create.append(
TestScore(
application=application,
test_type='ACT',
score=self.cleaned_data['act_score']
)
)
if test_scores_to_create:
TestScore.objects.bulk_create(test_scores_to_create)
return application
|
| Model: |
gemini-2.5-pro |
| Temperature: |
0.2 |
| Max output tokens: |
8192 |
| TopK: |
40.0 |
| TopP: |
0.95 |
|
