What’s new in Django 1.7Daniel Roseman@danielroseman

blog.roseman.org.ukairpair.me/danielroseman

About me

Web developer previously at Google, Global Radio, Glasses Direct, GDSDjango user since version 0.95

Occasional blogger on Django, Python, vim

Top answerer for Django at StackOverflow

What is new

● Migrations● App loading● System checks● Managers from custom QuerySets● Prefetch object● Custom lookups and transforms● Form errors improvements

Migrations

Awesome!

But… functionality is basically the same as South

Automatic migrations

● Detects schema changes● Add/remove columns, indexes, tables● Dependencies

manage.py makemigrations <app>

manage.py migrate

Migrations

No separate datamigration commandMigrations no longer load initial_dataRunPython - arbitrary functionality: callable(apps, schema_editor)

RunSQL replaces deprecated initial SQL data loading

App registry

List of registered apps:from django.apps import apps

Consists of AppConfig instancesNo need for models.py Hook for “startup” codeAdmin autodiscover called automatically

AppConfigs

Can use path to AppConfig subclass as entry in INSTALLED_APPSOtherwise module is checked for default_app_config variableIf none, uses default classSet app label or verbose_nameready() method for startup code

Checks framework

Static checking for appsLoads of built-in checksCustom checks - eg on field subclasses, or base model classes

./manage.py check

Custom QuerySets

Previously, create a custom Manager with extra methods - but it returns a plain QuerySet

Instead, create custom QuerySet, and use as_manager() to create manager automatically

Custom manager on relations

Choose which manager is used to return related querysetPre-filteringCalling custom methods

my_instance.related_set( manager='my_manager')

Prefetch object

Control operation of prefetch_related()● Specify base QuerySet for lookup - eg to

filter relation, or call select_related()● to_attr to save result to custom attribute ● can call multiple times with different

querysets

Lookups and Transforms

Custom lookups:MyModel.objects.filter(foo__ne='bar')

Transform comparisons:MyModel.objects.filter(foo__lq='bar')

Form errors

Simpler way to add errors from clean() method or from the view: form.add_error()Get raw error objects:form.errors.as_data()

Serialize errors to JSON:form.errors.as_json()

NON_FIELD_ERROR key in Meta.error_messages

Miscellaneous

● Field subclass deconstruct() method● QuerySet .update_or_create()● JsonResponse class● Template {% include %} can use anything

with a render method● Lots more admin control - site_header,

site_title, index_title, get_fields(), get_search_fields(), view_on_site…

The future

GSoC student Daniel Pyrathon: refactoring Meta to stable API

Allows any arbitrary class to define Meta and therefore make use of admin, model forms, etc

Example: GMail store