Everyday Refactoring of a Django Project

Transcript

1. EVERYDAY REFACTORING
   OF A DJANGO PROJECT
   

   View Slide

2. We all want to build
   new features
   

   View Slide

3. View Slide

4. The fast pace is fun
   but…
   

   View Slide

5. Haste is waste
   

   View Slide

6. What
   about
   technical
   debt?
   

   View Slide

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

   View Slide

8. Test it!
   

   View Slide

9. The later
   the change
   the higher
   the costs
   

   View Slide

10. Everyday refactoring
    

    View Slide

11. Usable
    TRUE
    Transparent
    Reasonable
    Exemplary
    

    View Slide

12. Exemplary
    

    View Slide

13. !
    

    View Slide

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

    View Slide

15. 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
    

    View Slide

16. "
    Foodipedia
    app
    ! Food Barcode
    model
    # Food
    model
    #
    ! Barcode Scan
    model
    "
    Barcodes
    app
    !
    

    View Slide

17. View Slide

18. 1
    add the new model
    to Foodipedia
    

    View Slide

19. 1
    add the new model
    to Foodipedia
    2
    Create the new app but
    leave FoodBarcode in
    Foodipedia
    

    View Slide

20. 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
    

    View Slide

21. 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
    

    View Slide

22. 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
    

    View Slide

23. 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
    

    View Slide

24. 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
    

    View Slide

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

    View Slide

26. 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
    %
    %
    %
    %
    %
    %
    %
    %
    

    View Slide

27. ana@lifesum.com
    anah
    @anhristova
    &
    '
    (
    

    View Slide