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Django Queryset

Subject : it-skills

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. The value given in the absence of a specified value for the field. This can be a value or a callable object. If callable it will be called every time a new object is created.
latest(field_name=None)
Meta class
default
iteration

2. Each one of these is a Python class that subclasses django.db.models.Model. Each attribute of one of these represents a database field.
one-to-one relationship
model
Q(question__istartswith='What')
help_text

3. These add custom "row-level" functionality to your objects. These act on a particular model instance.
lt
annotate(args - *kwargs)
only(*fields)
Custom model methods

4. If True - the table does not permit duplicate values for this field.
distinct()
unique
defer(*fields)
Restrictions on field names

5. 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.
~
intermediate models
delete()
null

6. The database that will be used if this query is executed now
db
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
==
Entry.objects.filter(pub_date__range=(start_date - end_date))

7. To activate your models
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
id field
Many-to-many relationship through an intermediate model
db

8. If this option is True - Django will store empty values as NULL in the database. Default is False.
class attributes
count()
null
filter chaining

9. A Q object that encapsulates queries for entries with a question value that starts with 'What' in a case-insensitive fashion.

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10. Returns a ValuesQuerySet -- a QuerySet that returns dictionaries when used as an iterable - rather than model-instance objects.
values(*fields)
ordered
get(**kwargs)
get(**kwargs)

11. 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.
year
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
__unicode__()
primary_key

12. This model method saves a model instance to the database. This method has no return value.
select_related()
save()
Entry.objects.filter(pub_date__year=2005).delete()
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)

13. Lookup type that corresponds to a boolean full-text search - taking advantage of full-text indexing. This is like contains but is significantly faster due to full-text indexing.
regex
blank
Abstract base class
search

14. Defines a many-to-many relationship. You use it just like any other Field type: by including it as a class attribute of your model.
ManyToManyField
Many-to-many relationship through an intermediate model
clear() method
aggregate(args - *kwargs)

15. Lookup type that returns results less than a given value.
Entry.objects.filter(pub_date__year=2005).delete()
lt
iterator()
save()

16. This object encapsulates a collection of keyword arguments - with the keys being field lookup types. These objects can be combined using the & and | operators - as well as negated with the ~ operator.
id field
add()
Q()
Entry.objects.filter(id__gt=4)

17. This is a criterion that narrow down a QuerySet based on given parameters.
save()
filter
delete()
Q()

18. Accomplish this by using the field name of related fields across models - separated by double underscores - until you get to the field you want. For example - to get all Entry objects with a Blog whose name is 'Beatles Blog': Entry.objects.filter(blo
exact
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
MultipleObjectsReturned
relationship spanning

19. Lookup type that returns results in a given list.
Meta class
in
Q()
distinct()

20. Manager method used to retrieve every object in a model.
all()
values(*fields)
Multi-table inheritance
clear() method

21. The default for this is the name of the child class followed by '_set'.
reverse name
regex
exists()
lt

22. Lookup type that finds a case-insensitive regular expression match.
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
iregex
iexact
__unicode__()

23. 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
one-to-one relationship
Abstract base class
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
annotate(args - *kwargs)

24. 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.
Multi-table inheritance
class attributes
in_bulk(id_list)
iregex

25. 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()
lt
OneToOneField
save()

26. Lookup type for date/datetime fields that finds a 'day of the week' match.
regex
week_day
exclude(**kwargs)
Meta class

27. This field is added automatically - but this behavior can be overridden
id field
reverse()
startswith
get_or_create(**kwargs)

28. This query deletes all Entry objects with a pub_date year of 2005.
when you add new apps to INSTALLED_APPS
Restrictions on field names
null
Entry.objects.filter(pub_date__year=2005).delete()

29. Defines a many-to-one relationship. ou use it just like any other Field type: by including it as a class attribute of your model.
id field
ForeignKey
distinct()
when you add new apps to INSTALLED_APPS

30. A Manager method that returns a new QuerySet containing objects that match the given lookup parameters.
filter(**kwargs)
distinct()
search
intermediate models

31. a QuerySet can be sliced - using Python's array-slicing syntax.
year
~
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
slicing

32. Exception raised by get(**kwargs) if more than one item matches the query.
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
Entry.objects.filter(pub_date__range=(start_date - end_date))
filter(**kwargs)
MultipleObjectsReturned

33. 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
year
many-to-many relationship
week_day
F()

34. Disjunction operator for Q objects.
Entry.objects.filter(pub_date__year=2005).delete()
all()
|
range

35. 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.
many-to-one relationship
range
blank
exclude(**kwargs)

36. 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.
related_name
values(*fields)
pickling
Entry.objects.filter(id__in=[1 - 3 - 4])

37. Negation operator for Q objects.
~
OneToOneField
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
annotate(args - *kwargs)

38. By default - results returned by a QuerySet are ordered by the ordering tuple given by the ordering option in the model's Meta. You can override this on a per-QuerySet basis by using the this method.
Many-to-many relationship through an intermediate model
Custom model methods
order_by(*fields)
when you add new apps to INSTALLED_APPS

39. 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.

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40. If True - this field is the primary key for the model.
primary_key
Proxy model
values(*fields)
count()

41. (1) These cannot be Python reserved words - because that would result in a Python syntax error. (2) These cannot contain more than one underscore in a row - due to the way Django's query lookup syntax works.
get_absolute_url()
none()
Restrictions on field names
create(**kwargs)

42. Exception raised by get(**kwargs) if no items match the query.
MultipleObjectsReturned
DoesNotExist
only(*fields)
many-to-one relationship

43. Returns an EmptyQuerySet -- a QuerySet that always evaluates to an empty list. This can be used in cases where you know that you should return an empty result set and your caller is expecting a QuerySet object (instead of returning an empty list - fo
filter(**kwargs)
values_list(*fields)
none()
when you add new apps to INSTALLED_APPS

44. Conjuntion operator for Q objects.
update(**kwargs)
Custom model methods
primary_key
&

45. This method is more or less the opposite of defer(). You call it with the fields that should not be deferred when retrieving a model. If you have a model where almost all the fields need to be deferred - using this method to specify the complementary
MultipleObjectsReturned
values(*fields)
range
only(*fields)

46. Defined by a ManyToManyField. You use it just like any other Field type: by including it as a class attribute of your model.
select_related()
Entry.objects.filter(pub_date__range=(start_date - end_date))
many-to-many relationship
Many-to-many relationship through an intermediate model

47. This represents a collection of objects from your database. It can have zero - one or many filters.
Field lookups
delete()
Q(question__istartswith='What')
QuerySet

48. 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.
none()
in_bulk(id_list)
Many-to-many relationship through an intermediate model
QuerySet

49. Returns the most recent object in the table - by date - using the field_name provided as the date field.
latest(field_name=None)
Entry.objects.filter(id__in=[1 - 3 - 4])
iendswith
values(*fields)

50. This query updates all the headlines with pub_date in 2007 to read 'Everything is the same'.

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