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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.
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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. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.
OneToOneField
week_day
ordered
choices

2. Lookup type that returns results greater than or equal to a given value.
annotate(args - *kwargs)
class attributes
gte
id field

3. Returns a dictionary of aggregate values (averages - sums - etc) calculated over the QuerySet. Each argument to this method specifies a value that will be included in the dictionary that is returned.
id field
null
aggregate(args - *kwargs)
Restrictions on field names

4. Can be used to remove all many-to-many relationships for an instance
clear() method
update()
endswith
week_day

5. Exception raised by get(**kwargs) if more than one item matches the query.
F()
defer(*fields)
delete()
MultipleObjectsReturned

6. Lookup type that returns results that fall into an inclusive date range.
|
Q()
range
model

7. a QuerySet can be sliced - using Python's array-slicing syntax.
defer(*fields)
slicing
year
filter chaining

8. If this option is True - Django will store empty values as NULL in the database. Default is False.
null
help_text
update()
week_day

9. If True - the table does not permit duplicate values for this field.
unique
pk
create(**kwargs)
filter chaining

10. 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

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

12. Takes the ouput of one filter and uses it as input for another filter. This works because a refinement of a QuerySet is itself a QuerySet.
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
filter chaining
relationship spanning
exists()

13. Defined by a OneToOneField. You use it just like any other Field type: by including it as a class attribute of your model.
Many-to-many relationship through an intermediate model
one-to-one relationship
slicing
filter chaining

14. Conjuntion operator for Q objects.
update(**kwargs)
one-to-one relationship
order_by(*fields)
&

15. This model method is used for updating a ManyToManyField.
isnull
create(**kwargs)
Entry.objects.filter(id__gt=4)
add()

16. 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()
order_by(*fields)
evaluation
lte
range

17. 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
class type
only(*fields)
Abstract base class
add()

18. 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
ManyToManyField
count()
update(**kwargs)
intermediate models

19. 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.
delete()
year
get_or_create(**kwargs)
choices

20. Lookup type for date/datetime fields that finds a 'day of the week' match.
F()
week_day
gte
in_bulk(id_list)

21. 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
evaluation
slicing
pickling
intermediate models

22. When to run syncdb
Entry.objects.filter(id__gt=4)
when you add new apps to INSTALLED_APPS
Manager methods
pickling

23. Lookup type that tests for inclusion in a case-sensitive fashion.
contains
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
filter
==

24. 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
defer(*fields)
ForeignKey
values_list(*fields)

25. This model method saves a model instance to the database. This method has no return value.
null
save()
model
iteration

26. Returns an integer representing the number of objects in the database matching the QuerySet. This never raises exceptions.
ManyToManyField
Q(question__istartswith='What')
count()
Many-to-many relationship through an intermediate model

27. A Python "magic method" that returns a unicode "representation" of any object.
ForeignKey
choices
__unicode__()
slicing

28. Fields are specified by these
filter chaining
F()
Multi-table inheritance
class attributes

29. 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.
save()
through argument
update()
delete()

30. Manager method used to retrieve every object in a model.
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
regex
default
all()

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

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

32. The default for this is the name of the child class followed by '_set'.
reverse name
Entry.objects.filter(id__gt=4)
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
Field lookups

33. Each one of these is a Python class that subclasses django.db.models.Model. Each attribute of one of these represents a database field.
iendswith
model
Many-to-many relationship through an intermediate model
defer(*fields)

34. 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
isnull
defer(*fields)
model
filter

35. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.
lt
Many-to-many relationship to self
distinct()
contains

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

37. 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.
istartswith
exact
order_by(*fields)
Multi-table inheritance

38. The database that will be used if this query is executed now
range
db
get_absolute_url()
count()

39. Negation operator for Q objects.
iteration
month
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
~

40. This gives your model metadata.
one-to-one relationship
Meta class
|
isnull

41. These add custom "row-level" functionality to your objects. These act on a particular model instance.
values(*fields)
help_text
add()
Custom model methods

42. Lookup type that returns results with a case-sensitive end sequence.
related_name
DoesNotExist
endswith
delete()

43. This query finds all entries with an id greater than 4.
relationship spanning
ForeignKey
Entry.objects.filter(id__gt=4)
one-to-one relationship

44. Lookup type for date/datetime fields that finds an exact day match.
get_or_create(**kwargs)
related_name
day
values_list(*fields)

45. Lookup type that returns results with a case-sensitive start sequence.
Q(question__istartswith='What')
startswith
one-to-one relationship
intermediate models

46. 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.
search
~
filter(**kwargs)
OneToOneField

47. 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.
Proxy model
default
Manager
through argument

48. 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.
Many-to-many relationship to self
intermediate models
week_day
Entry.objects.filter(pub_date__range=(start_date - end_date))

49. Lookup type that returns results in a given list.
Entry.objects.filter(pub_date__range=(start_date - end_date))
count()
in
intermediate models

50. 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
select_related()
db
==
OneToOneField