django 1.9 notes

django1.9.rst

Django 1.9

RC1 released November 16th

contrib.postgres (round 2)

JSONField

Can store any valid JSON (uses PG 9.4's jsonb type)

While custom indexing isn't supported in JSON, can create GIN indices manually.

ORM support:

• arbitrarily deep path lookups - data__owner__other_pets__0__name
• contains - @> - query is a subset of data
• contained_by - <@ - data is a subset of query
• has_key - ? - key is present
• has_any_key - ?| - any key in a provided list is present
• has_keys - ?& - all keys in a provided list are present

https://docs.djangoproject.com/en/1.9/ref/contrib/postgres/fields/#django.contrib.postgres.fields.JSONField

Postgres aggregation functions:

ArrayAgg, StringAgg Statistical aggregates: correlation, regressions

https://docs.djangoproject.com/en/1.9/ref/contrib/postgres/aggregates/

TransactionNow()

useful to give all items within a transaction same update time

From 1.8:

• ArrayField
• HStoreField - probably avoid using this
• {...}RangeField

Aside: Database functions & custom lookups:

These new fields rely heavily on custom lookups & database functions, a powerful feature for using nicer database features without resorting to raw SQL every time.

Lookups: https://docs.djangoproject.com/en/1.9/ref/models/lookups/

Lookup Example

@TextField.register_lookup
class Fulltext(Lookup):
    lookup_name = 'ftsearch'

    def as_sql(self, compiler, connection):
        lhs, lhs_params = self.process_lhs(compiler, connection)
            rhs, rhs_params = self.process_rhs(compiler, connection)
            params = lhs_params + rhs_params
            return "to_tsvector('english', %s) @@ to_tsquery('english', %s)" % (lhs, rhs), params


# elsewhere...
Book.objects.filter(text__ftsearch='green', author='Dr. Seuss')

Functions: https://docs.djangoproject.com/en/1.9/ref/models/database-functions/

Function Example

class TsVector(Func):
    function = 'to_tsvector'


Book.objects.annotate(tsv=TsVector('english', F('text')))

Lots of contrib.gis was rewritten to use it and plenty of useful functions like Lower()/Upper()/Now() were added.

Permissions Mixins

1.9 adds permission mixins for Class Based Views borrowing heavily from django-braces:

• AccessMixin
• LoginRequiredMixin
• PermissionRequiredMixin
• UserPassesTestMixin

All work similarly to how their decorator equivalents worked.

https://docs.djangoproject.com/en/1.9/topics/auth/default/#the-loginrequired-mixin

Password Validation

Set via AUTH_PASSWORD_VALIDATORS. Four provided by default:

• UserAttributeSimilarityValidator - not their name/email/etc.
• MinimumLengthValidator - set a minimum length
• CommonPasswordValidator - uses an included (configurable) list of 1000 most common passwords
• NumericPasswordValidator - not entirely numeric

https://docs.djangoproject.com/en/1.9/topics/auth/passwords/#password-validation

Other Useful Things

• manage.py test --parallel
• manage.py sendtestemail

• .delete() returns number of objects deleted (including cascades)

  >>> num, types = Book.objects.delete()
  3, {'bookstore.Book': 1, 'bookstore.Review': 2}

• simple_tag() can store results using 'as'
• nicer admin template w/ flat look & SVG icons
• test responses now have a .json() method, like requests' Response
• on_commit() hook for post-transaction actions (cache invalidation & notifications)

And another hundred small things: https://docs.djangoproject.com/en/1.9/releases/1.9/

What's Gone

syncdb

• no more automated fixture loading
• everything needs migrations

Goodbye Python 3.2 and 3.3!

tons of vendorized imports are gone as part of dropping support for old Python versions (dictconfig, importlib, tzinfo, unittest, etc.)

IPAddressField

• replace w/ GenericIPAddressField

in 1.10, patterns() is finally going away

Quirks

related_objects.add() now takes a bulk parameter that defaults to True

similarly, assignment now uses a manager.set() method instead of delete() and then add()

This is a lot faster than the old way but has a backwards-incompatible issue: objects must be already saved if you're using bulk which breaks some old code