EVERYDAY REFACTORING OF A DJANGO PROJECT 

We all want to build new features 

No content

The fast pace is fun but… 

Haste is waste 

What about technical debt? 

If it ain't broke, don't fix it. Rewrite the whole codebase! 

Test it! 

The later the change the higher the costs 

Everyday refactoring 

Usable TRUE Transparent Reasonable Exemplary 

Exemplary 

! 

class BarcodeScan(models.Model): barcode = models.CharField(unique=True, max_length=100) user = models.ForeignKey(‘accounts.UserProfile') created = models.DateTimeField(auto_now_add=True) 

class Food(models.Model): name = models.CharField(max_length=100) calories = models.Integer(default=0) class FoodBarcode(models.Model): barcode = models.CharField(unique=True, max_length=100) food = models.ForeignKey(Food) foodipedia/models.py 

" Foodipedia app ! Food Barcode model # Food model # ! Barcode Scan model " Barcodes app ! 

No content

1 add the new model to Foodipedia 

1 add the new model to Foodipedia 2 Create the new app but leave FoodBarcode in Foodipedia 

1 add the new model to Foodipedia 2 3 Create the new app but leave FoodBarcode in Foodipedia Create the new app and migrate FoodBarcode and its data 

1 add the new model to Foodipedia 2 3 4 Create the new app but leave FoodBarcode in Foodipedia Create the new app and refactor but use db_table to avoid schema changes Create the new app and migrate FoodBarcode and its data 

class FoodBarcode(models.Model): barcode = models.CharField(unique=True, max_length=100) food = models.ForeignKey('foodipedia.Food') class Meta: db_table = u'foodipedia_foodbarcode' class BarcodeScan(models.Model): barcode = models.CharField(unique=True, max_length=100) user = models.ForeignKey(‘accounts.UserProfile') created = models.DateTimeField(auto_now_add=True) barcodes/models.py 

class FoodBarcode(models.Model): barcode = models.CharField(unique=True, max_length=100) food = models.ForeignKey('foodipedia.Food') class Meta: db_table = u'foodipedia_foodbarcode' class BarcodeScan(models.Model): barcode = models.CharField(unique=True, max_length=100) user = models.ForeignKey(‘accounts.UserProfile') created = models.DateTimeField(auto_now_add=True) barcodes/models.py 

class Migration(DataMigration): def forwards(self, orm): orm['contenttypes.contenttype'].objects.filter( app_label='foodipedia', model='foodbarcode', ).update(app_label='barcodes') barcodes/migrations/0001_initial.py ./manage.py datamigration barcodes 0001_initial --frozen contenttypes 

class Migration(SchemaMigration): depends_on = (('barcodes', '0001_initial'),) def forwards(self, orm): pass foodipedia/migrations/0012_move_foodbarcode.py ./manage.py schemamigration foodipedia --auto 

Geek & Poke Font Awesome Practical Object-Oriented Design in Ruby by Sandi Metz hilite.me RESOURCES licensed under $ licensed under SIL OFL Stack Overflow: Easiest way to rename a model using Django/South? Two Scoops of Django: Best Practices for Django 1.6 by Daniel Greenfeld & Audrey Roy % % % % % % % % 

[email protected] anah @anhristova & ' (