Topic guide Pagination

Under the hood, all methods of pagination use the Paginator class. It does all the heavy lifting of actually splitting a QuerySet into Page objects.

Topic guide Pagination

Here’s an example using Paginator in a view function to paginate a queryset: In the template list.html, you can include navigation between pages in the same way as in the template for the ListView above.

Topic guide Performance and optimization Understanding laziness

Django is itself quite lazy. A good example of this can be found in the evaluation of QuerySets. QuerySets are lazy.

Topic guide Security in Django

This can result in records being deleted or data leakage. Django’s querysets are protected from SQL injection since their queries are constructed using query parameterization. A query’s SQL code is defined separately from the query’s parameters.

Topic guide Serializing Django objects

At the highest level, you can serialize data like this: The arguments to the serialize function are the format to serialize the data to (see Serialization formats) and a QuerySet to serialize.

Index

| | | | --- | --- | | - W3CGeoFeed (class in django.contrib.gis.feeds) - Warning (class in django.core.checks) - warp() (GDALRaster method) - week - field lookup type - week (WeekMixin attribute) - week_day - field lookup type - …

Index

| | | | --- | --- | | - y (LineString attribute) - (Point attribute) - year - field lookup type - year (YearMixin attribute) - year_format (YearMixin attribute) - YEAR_MONTH_FORMAT - setting | - YearArchiveView (built-in class) - …

Internals Django Deprecation Timeline

django.core.paginator.QuerySetPaginator will be removed. A model’s Meta.ordering will no longer affect GROUP BY queries. django.contrib.postgres.fields.FloatRangeField and django.contrib.postgres.forms.FloatRangeField will be removed. The FILE_CHARSET setting will be removed. django.contrib.staticfiles.storage.CachedStaticFilesStorage will be removed. RemoteUserBackend.configure_user() will require request as the first positional argument.

Reference Databases SQLite notes

These are triggered when using the iexact or contains filters in Querysets. The behavior splits into two cases: For substring matching, all matches are done case-insensitively. That is a filter such as filter(name__contains="aa") will match a name of "Aabb".

Reference Conditional Expressions Advanced queries

What if we want to find out how many clients there are for each account_type?

Reference Model index reference Index options

Index.condition If the table is very large and your queries mostly target a subset of rows, it may be useful to restrict an index to that subset. Specify a condition as a Q.

FAQ FAQ: The admin

Using the same trick of extracting the user from the request, the get_queryset() and has_change_permission() can be used to control the visibility and editability of objects in the admin.

Index

… method) - page_kwarg (django.views.generic.list.MultipleObjectMixin attribute) - page_range (Paginator attribute) - PageNotAnInteger - paginate_by (django.views.generic.list.MultipleObjectMixin attribute) - paginate_orphans (django.views.generic.list.MultipleObjectMixin attribute) - paginate_queryset() (django.views.generic.list.MultipleObjectMixin method) - Paginator (class in django.core.paginator) - paginator (ModelAdmin attribute) - (Page attribute) - (Sitemap attribute) - paginator_class …

Index

… django.contrib.postgres.fields) - RangeWidget (class in django.contrib.postgres.forms) - Rank (class in django.db.models.functions) - RasterField (class in django.contrib.gis.db.models) - raw() (in module django.db.models.query.QuerySet) - (Manager method) - raw_id_fields (InlineModelAdmin attribute) - (ModelAdmin attribute) - RawSQL (class in django.db.models.expressions) - re_path() (in module …

Index

… - setting - SecurityMiddleware (class in django.middleware.security) - seekable() (HttpResponse method) - Select (class in django.forms) - select_for_update() (in module django.db.models.query.QuerySet) - select_on_save (Options attribute) - select_related() (in module django.db.models.query.QuerySet) - select_template() (Engine method) - (in module django.template.loader) - SelectDateWidget …

Index

… - unary_union (GEOSGeometry attribute) - Union (class in django.contrib.gis.db.models) - (class in django.contrib.gis.db.models.functions) - union() (GEOSGeometry method) - (in module django.db.models.query.QuerySet) - (OGRGeometry method) - unique (Field attribute) - unique_for_date (Field attribute) - unique_for_month (Field attribute) - unique_for_year (Field attribute) …

How-to How to write custom lookups

For instance, if you want to filter a queryset based on the equality of the left and right-hand side insensitively to some SQL function. Let’s examine case-insensitive transformations here.

How-to How to create custom model fields Writing a field subclassUseful methods

If your custom Field class deals with data structures that are more complex than strings, dates, integers, or floats, then you may need to override from_db_value() and to_python().

Django documentation

… Learn more about it below: Models: Introduction to models | Field types | Indexes | Meta options | Model class QuerySets: Making queries | QuerySet method reference | Lookup expressions Model instances: Instance methods | Accessing related objects Migrations: Introduction …

Internals Django Deprecation Timeline

Support for pytz timezones will be removed. The is_dst argument will be removed from: QuerySet.datetimes() django.utils.timezone.make_aware() django.db.models.functions.Trunc() django.db.models.functions.TruncSecond() django.db.models.functions.TruncMinute() django.db.models.functions.TruncHour() django.db.models.functions.TruncDay() django.db.models.functions.TruncWeek() django.db.models.functions.TruncMonth() django.db.models.functions.TruncQuarter() django.db.models.functions.TruncYear() The django.contrib.gis.admin.GeoModelAdmin and OSMGeoAdmin classes will be removed. The undocumented BaseForm._html_output() method will be removed.