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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. 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.
unique
in_bulk(id_list)
week_day
when you add new apps to INSTALLED_APPS

2. 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
through argument
values(*fields)
Many-to-many relationship through an intermediate model
create(**kwargs)

3. This query finds all entries between a start date of start_date and an end date of end_date.
Model metadata
Entry.objects.filter(pub_date__range=(start_date - end_date))
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
contains

4. A Python "magic method" that returns a unicode "representation" of any object.
aggregate(args - *kwargs)
MultipleObjectsReturned
one-to-one relationship
__unicode__()

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()
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
evaluation
Meta class
intermediate models

6. This model method saves a model instance to the database. This method has no return value.
isnull
when you add new apps to INSTALLED_APPS
save()
clear() method

7. 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.
Entry.objects.filter(pub_date__range=(start_date - end_date))
ordered
unique
many-to-one relationship

8. This field is added automatically - but this behavior can be overridden
QuerySet
id field
isnull
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)

9. restrictions on ________: (1) Your intermediate model must contain one - and only one - foreign key to the target model. (2) Your intermediate model must contain one - and only one - foreign key to the source model. (3) When defining a many-to-many r
intermediate models
Entry.objects.filter(pub_date__range=(start_date - end_date))
get_absolute_url()
Entry.objects.filter(id__in=[1 - 3 - 4])

10. Manager method used to retrieve every object in a model.
primary_key
pk
save()
all()

11. 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.
~
add()
pickling
reverse name

12. A manager method that returns a new QuerySet containing objects that do not match the given lookup parameters.
==
exclude(**kwargs)
filter(**kwargs)
Entry.objects.filter(id__in=[1 - 3 - 4])

13. (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.
Restrictions on field names
clear() method
Entry.objects.filter(id__in=[1 - 3 - 4])
save()

14. 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
delete()
gt
Abstract base class
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)

15. Can be used to remove all many-to-many relationships for an instance
Custom model methods
&
clear() method
choices tuple

16. If you are using this attribute on a ForeignKey or ManyToManyField - you must always specify a unique reverse name for the field.
only(*fields)
count()
evaluation
related_name

17. This query deletes all Entry objects with a pub_date year of 2005.
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
many-to-one relationship
Entry.objects.filter(pub_date__year=2005).delete()
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)

18. This model method is used for updating a ManyToManyField.
get_absolute_url()
ordered
add()
choices tuple

19. 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.
Many-to-many relationship through an intermediate model
get_or_create(**kwargs)
get_absolute_url()
exclude(**kwargs)

20. A QuerySet is iterable - and it executes its database query the first time you iterate over it.
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
iteration
blank
|

21. Use this method to reverse the order in which a queryset's elements are returned. Calling this method a second time restores the ordering back to the normal direction.
annotate(args - *kwargs)
Abstract base class
lt
reverse()

22. Exception raised by get(**kwargs) if more than one item matches the query.
MultipleObjectsReturned
create(**kwargs)
through argument
order_by(*fields)

23. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.
ordered
iendswith
Entry.objects.filter(id__in=[1 - 3 - 4])
pickling

24. Lookup type that returns results less than or equal to a given value.
~
day
lte
choices

25. Fields are specified by these
__unicode__()
class attributes
Meta class
get_or_create(**kwargs)

26. If True - this field is the primary key for the model.
relationship spanning
primary_key
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
using(alias)

27. Lookup type for date/datetime fields that finds an exact year match. Takes a four-digit year.
year
default
day
endswith

28. This query uses an F object to increment the pingback count for every entry in the blog.

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

29. Lookup type that returns results with a case-insensitive end sequence.
null
iendswith
clear() method
many-to-many relationship

30. Lookup type that yields an "exact" match. If you don't provide a lookup type -- that is - if your keyword argument doesn't contain a double underscore -- the lookup type is assumed to be of this sort.
delete()
exact
Entry.objects.filter(id__in=[1 - 3 - 4])
iexact

31. Lookup type for date/datetime fields that finds an exact month match. Takes an integer 1 (January) through 12
isnull
default
Entry.objects.filter(id__gt=4)
month

32. These methods are intended to do "table-wide" things.
update(**kwargs)
==
endswith
Manager methods

33. Lookup type that returns results with a case-sensitive start sequence.
Abstract base class
none()
startswith
&

34. 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
relationship spanning
iterator()
F()
all()

35. 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
defer(*fields)
iteration
Many-to-many relationship to self

36. Keyword shortcut for looking up an object by primary key.
all()
~
pk
gte

37. 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.
create(**kwargs)
delete()
lte
Q()

38. 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
Entry.objects.filter(pub_date__year=2005).delete()
class attributes
update(**kwargs)
none()

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

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

40. The first element in this iterable is the value that will be stored in the database - the second element will be displayed by the admin interface - or in a ModelChoiceField.
delete()
choices tuple
ForeignKey
get_absolute_url()

41. what the field _______ determines: (1) The database column type (e.g. INTEGER - VARCHAR); (2) The widget to use in Django's admin interface - if you care to use it (e.g. <input type="text"> - <select>); (3) The minimal validation requirements - used
endswith
Entry.objects.filter(pub_date__range=(start_date - end_date))
distinct()
class type

42. In some complex data-modeling situations - your models might contain a lot of fields - some of which could contain a lot of data (for example - text fields) - or require expensive processing to convert them to Python objects. If you are using the res
one-to-one relationship
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
defer(*fields)
QuerySet

43. To activate your models
Entry.objects.filter(id__in=[1 - 3 - 4])
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
reverse()
db

44. Disjunction operator for Q objects.
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
|
Many-to-many relationship to self
Q(question__istartswith='What')

45. 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.
ForeignKey
order_by(*fields)
Multi-table inheritance
intermediate models

46. 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.
filter chaining
aggregate(args - *kwargs)
Q()
search

47. Returns a new QuerySet containing objects that match the given lookup parameters.
search
iteration
filter(**kwargs)
reverse name

48. 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.
id field
values_list(*fields)
pickling
relationship spanning

49. Defined by a OneToOneField. You use it just like any other Field type: by including it as a class attribute of your model.
iexact
one-to-one relationship
F()
select_related()

50. 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.
one-to-one relationship
pk
Many-to-many relationship through an intermediate model
Meta class