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Django Queryset

Subject : it-skills

Instructions:

Answer 50 questions in 15 minutes.
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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. Returns a QuerySet that will automatically "follow" foreign-key relationships - selecting that additional related-object data when it executes its query. This is a performance booster which results in (sometimes much) larger queries but means later u
filter(**kwargs)
__unicode__()
select_related()
add()

2. Lookup type that returns results less than or equal to a given value.
in
exists()
month
lte

3. This gives your model metadata.
Meta class
intermediate models
one-to-one relationship
update()

4. Lookup type that returns results greater than or equal to a given value.
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
gte
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
Entry.objects.filter(pub_date__year=2005).delete()

5. 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
year
isnull
iteration
all()

6. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.
__unicode__()
exists()
values(*fields)
distinct()

7. This represents a collection of objects from your database. It can have zero - one or many filters.
in_bulk(id_list)
QuerySet
|
reverse()

8. If you are using this attribute on a ForeignKey or ManyToManyField - you must always specify a unique reverse name for the field.
when you add new apps to INSTALLED_APPS
related_name
gte
pk

9. 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.
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
values(*fields)
add()
in_bulk(id_list)

10. 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
aggregate(args - *kwargs)
iterator()
values_list(*fields)
one-to-one relationship

11. Specifies the model that will be used to govern the many-to-many relationship. You can then put extra fields on the intermediate model. The intermediate model is associated with the ManyToManyField using this to point to the model that will act as an
Manager methods
search
through argument
iterator()

12. 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.
F()
many-to-one relationship
select_related()
week_day

13. 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
Many-to-many relationship through an intermediate model
exists()
isnull
F()

14. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.
ordered
year
dates(field - kind - order='ASC')
Q()

15. 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.
in_bulk(id_list)
isnull
ManyToManyField
Many-to-many relationship to self

16. 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
OneToOneField
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
startswith
only(*fields)

17. 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.
OneToOneField
filter(**kwargs)
default
search

18. 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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19. 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()
delete()
count()
evaluation
exact

20. Lookup type that finds a case-sensitive regular expression match.
iteration
==
startswith
regex

21. This class type is useful when you just want to use the parent class to hold information that you don't want to have to type out for each child model. This class isn't going to ever be used in isolation. When it is used as a base class for other mode
filter chaining
get_or_create(**kwargs)
Abstract base class
Q(question__istartswith='What')

22. The database that will be used if this query is executed now
exact
get(**kwargs)
db
class attributes

23. Keyword shortcut for looking up an object by primary key.
pk
get_or_create(**kwargs)
Abstract base class
one-to-one relationship

24. 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.
many-to-many relationship
ordered
ForeignKey
Abstract base class

25. Conjuntion operator for Q objects.
&
iteration
only(*fields)
Many-to-many relationship through an intermediate model

26. A Manager method that returns a new QuerySet containing objects that match the given lookup parameters.
filter(**kwargs)
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
save()
in

27. Lookup type that tests for inclusion in a case-sensitive fashion.
intermediate models
iterator()
istartswith
contains

28. This is a criterion that narrow down a QuerySet based on given parameters.
defer(*fields)
gte
get(**kwargs)
filter

29. This query deletes all Entry objects with a pub_date year of 2005.
search
gt
Entry.objects.filter(pub_date__year=2005).delete()
update()

30. Lookup type that returns results less than a given value.
iteration
lt
update()
many-to-many relationship

31. Lookup type that takes either True or False and corresponds to SQL queries of IS NULL and IS NOT NULL - respectively.
none()
isnull
delete()
startswith

32. Returns the most recent object in the table - by date - using the field_name provided as the date field.
filter
filter(**kwargs)
values(*fields)
latest(field_name=None)

33. Can be used to remove all many-to-many relationships for an instance
blank
get(**kwargs)
Custom model methods
clear() method

34. This query finds all entries between a start date of start_date and an end date of end_date.
clear() method
isnull
search
Entry.objects.filter(pub_date__range=(start_date - end_date))

35. 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.
all()
order_by(*fields)
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
distinct()

36. Lookup type that returns results with a case-insensitive start sequence.
iendswith
filter chaining
istartswith
Custom model methods

37. (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.
one-to-one relationship
Restrictions on field names
iexact
all()

38. 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
intermediate models
reverse()
Proxy model
evaluation

39. Negation operator for Q objects.
~
using(alias)
Entry.objects.filter(pub_date__range=(start_date - end_date))
filter chaining

40. 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()
MultipleObjectsReturned
filter(**kwargs)
iendswith

41. A convenience method for constructing an object and saving it all in one step.
year
delete()
count()
create(**kwargs)

42. This query finds all entries with an id greater than 4.
primary_key
default
reverse name
Entry.objects.filter(id__gt=4)

43. This model method is used for updating a ManyToManyField.
aggregate(args - *kwargs)
add()
class attributes
only(*fields)

44. Disjunction operator for Q objects.
Entry.objects.filter(pub_date__range=(start_date - end_date))
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
|
get_absolute_url()

45. This tells Django how to calculate the URL for an object. Django uses this in its admin interface - and any time it needs to figure out a URL for an object.
Q()
get_absolute_url()
DoesNotExist
annotate(args - *kwargs)

46. a QuerySet can be sliced - using Python's array-slicing syntax.
defer(*fields)
latest(field_name=None)
slicing
all()

47. 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)
DoesNotExist
Model metadata
db
OneToOneField

48. Exception raised by get(**kwargs) if more than one item matches the query.
MultipleObjectsReturned
add()
update()
~

49. Lookup type that yields a case-insensitive match.
iexact
iterator()
defer(*fields)
one-to-one relationship

50. A Q object that asks for entries with a question value that start with 'Who' or do not have a publication date of 2005.

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