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Django Queryset

Subject : it-skills

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Answer 50 questions in 15 minutes.
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1. This method is for controlling which database the QuerySet will be evaluated against if you are using more than one database. The only argument this method takes is the alias of a database - as defined in DATABASES.
using(alias)
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
Q(question__istartswith='What')
iterator()

2. Lookup type for date/datetime fields that finds a 'day of the week' match.
none()
all()
week_day
contains

3. Returns a copy of the current QuerySet (or QuerySet subclass you pass in). This can be useful in some situations where you might want to pass in either a model manager or a QuerySet and do further filtering on the result. You can safely call all() on
pk
all()
choices tuple
many-to-many relationship

4. Sometimes - the Django query syntax by itself can't easily express a complex WHERE clause. For these edge cases - Django provides this QuerySet modifier -- a hook for injecting specific clauses into the SQL generated by a QuerySet.
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
iendswith
class type
aggregate(args - *kwargs)

5. Evaluation happens upon use the "step" parameter of slice syntax - the first time you iterate over it - when pickling or caching results - upon calling repr() - upon calling len() - upon calling list() - upon calling bool()
choices tuple
evaluation
using(alias)
relationship spanning

6. Fields are specified by these
class attributes
Multi-table inheritance
all()
gt

7. Returns a DateQuerySet -- a QuerySet that evaluates to a list of datetime.datetime objects representing all available dates of a particular kind within the contents of the QuerySet.

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183

8. A manager method which returns a single object. If there are no results that match the query - this method will raise a DoesNotExist exception. If more than one item matches this query - the method will raise MultipleObjectsReturned.
get(**kwargs)
reverse()
range
latest(field_name=None)

9. Here - you can't use add - create - or assignment (i.e. - beatles.members = [...]) to create relationships. You need to specify all the detail for the relationship required by the intermediate model.
unique
count()
week_day
Many-to-many relationship through an intermediate model

10. Each one of these is a Python class that subclasses django.db.models.Model. Each attribute of one of these represents a database field.
model
distinct()
week_day
get_or_create(**kwargs)

11. Lookup type that returns results that fall into an inclusive date range.
filter
MultipleObjectsReturned
range
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)

12. Extra text to be displayed under the field on the object's admin form to provide assistance to users. It's useful for documentation even if your object doesn't have an admin form.
Many-to-many relationship to self
month
in
help_text

13. This model type is useful if you only want to modify the Python-level behavior of a model - without changing the models fields in any way. This creates a stand-in for the original model. You can create - delete and update instances of this new model
filter(**kwargs)
Proxy model
when you add new apps to INSTALLED_APPS
unique

14. These methods are intended to do "table-wide" things.
Manager methods
exclude(**kwargs)
reverse()
&

15. Lookup type for date/datetime fields that finds an exact year match. Takes a four-digit year.
gte
year
ForeignKey
through argument

16. Defined by django.db.models.ForeignKey. You use it just like any other Field type: by including it as a class attribute of your model.
iregex
class type
many-to-one relationship
db

17. Lookup type that returns results in a given list.
in
startswith
lt
latest(field_name=None)

18. These are "anything that's not a field" - such as ordering options (ordering) - database table name (db_table) - or human-readable singular and plural names (verbose_name and verbose_name_plural)
Model metadata
F()
year
get_or_create(**kwargs)

19. Evaluates the QuerySet (by performing the query) and returns an iterator over the results. A QuerySet typically caches its results internally so that repeated evaluations do not result in additional queries; this method will instead read results dire
iterator()
year
startswith
gte

20. This model method is used for updating a ManyToManyField.
endswith
add()
using(alias)
filter(**kwargs)

21. Performs an SQL delete query on all rows in the QuerySet. This method is applied instantly. You cannot call this method on a QuerySet that has had a slice taken or can otherwise no longer be filtered.
isnull
blank
lt
delete()

22. Lookup type that yields a case-insensitive match.
iexact
using(alias)
endswith
in_bulk(id_list)

23. Lookup type that returns results with a case-insensitive start sequence.
istartswith
contains
all()
Meta class

24. Disjunction operator for Q objects.
Entry.objects.filter(pub_date__year=2005).delete()
save()
reverse name
|

25. Performs an SQL update query for the specified fields - and returns the number of rows affected. This method is applied instantly and the only restriction on the QuerySet that is updated is that it can only update columns in the model's main table. F
istartswith
Many-to-many relationship to self
get_absolute_url()
update(**kwargs)

26. This object allows you to compare the value of a model field with another field on the same model. Django supports the use of addition - subtraction - multiplication - division and modulo arithmetic with these objects - both with constants and with o
F()
Abstract base class
order_by(*fields)
reverse name

27. This is a criterion that narrow down a QuerySet based on given parameters.
filter
Q(question__istartswith='What')
Many-to-many relationship through an intermediate model
get(**kwargs)

28. If you pickle a QuerySet - this will force all the results to be loaded into memory prior to pickling. When you unpickle a QuerySet - it contains the results at the moment it was pickled - rather than the results that are currently in the database.
pickling
__unicode__()
create(**kwargs)
none()

29. Used to get a QuerySet for a model. This is called 'objects' by default.
order_by(*fields)
isnull
none()
Manager

30. A manager method that returns a new QuerySet containing objects that do not match the given lookup parameters.
through argument
pk
exclude(**kwargs)
one-to-one relationship

31. Returns an integer representing the number of objects in the database matching the QuerySet. This never raises exceptions.
count()
related_name
class type
get(**kwargs)

32. Returns a new QuerySet containing objects that match the given lookup parameters.
Model metadata
filter chaining
none()
filter(**kwargs)

33. A convenience method for looking up an object with the given kwargs - creating one if necessary.
ManyToManyField
filter
in_bulk(id_list)
get_or_create(**kwargs)

34. This method returns tuples of values when iterated over. Each tuple contains the value from the respective field passed into the call to this method -- so the first item is the first field - etc.
exists()
when you add new apps to INSTALLED_APPS
values_list(*fields)
OneToOneField

35. Returns True if the QuerySet contains any results - and False if not. This tries to perform the query in the simplest and fastest way possible - but it does execute nearly the same query. This means that calling this method on a queryset is faster th
filter
exists()
save()
filter chaining

36. An iterable (e.g. - a list or tuple) of 2-tuples to use as options for this field. If this is given - Django's admin will use a select box instead of the standard text field and will limit options to those given.
choices
==
in_bulk(id_list)
Entry.objects.filter(id__in=[1 - 3 - 4])

37. Adds to each object in the QuerySet with the provided list of aggregate values (averages - sums - etc) that have been computed over the objects that are related to the objects in the QuerySet. Each argument to this is content that will be added to ea
ManyToManyField
Manager methods
annotate(args - *kwargs)
intermediate models

38. If this option is True - the field is allowed to be blank. Default is False.
model
Restrictions on field names
add()
blank

39. In this case - an intermediate model can have multiple foreign keys to the source model. Here - two foreign keys to the same model are permitted - but they will be treated as the two (different) sides of the many-to-many relation.
year
in_bulk(id_list)
Many-to-many relationship to self
Entry.objects.filter(pub_date__year=2005).delete()

40. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.
distinct()
Entry.objects.filter(pub_date__year=2005).delete()
get_or_create(**kwargs)
iterator()

41. This sets a field to a particular value for all the objects in a QuerySet. You can only set non-relation fields and ForeignKey fields using this method.
update()
Model metadata
all()
slicing

42. A QuerySet is iterable - and it executes its database query the first time you iterate over it.
reverse name
iteration
Q(question__istartswith='What')
dates(field - kind - order='ASC')

43. Negation operator for Q objects.
Entry.objects.filter(pub_date__range=(start_date - end_date))
blank
~
Proxy model

44. These are specified as keyword arguments to the QuerySet methods filter() - exclude() and get(). These take the form field__lookuptype=value .
lt
F()
none()
Field lookups

45. If True - the table does not permit duplicate values for this field.
year
unique
iteration
ordered

46. Lookup type that returns results greater than or equal to a given value.
save()
gte
create(**kwargs)
select_related()

47. Takes a list of primary-key values and returns a dictionary mapping each primary-key value to an instance of the object with the given ID.
in_bulk(id_list)
reverse name
choices
distinct()

48. Can be used to remove all many-to-many relationships for an instance
pickling
many-to-many relationship
==
clear() method

49. Defines a one-to-one relationship. You use it just like any other Field type: by including it as a class attribute of your model.
choices tuple
__unicode__()
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
OneToOneField

50. This query finds all entries with an id in the list [1 - 3 - 4]
Entry.objects.filter(id__in=[1 - 3 - 4])
exists()
choices
iterator()