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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 an integer representing the number of objects in the database matching the QuerySet. This never raises exceptions.
reverse()
gt
count()
isnull

2. 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)
iterator()
Model metadata
Field lookups
get(**kwargs)

3. 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.
lte
Q()
related_name
values_list(*fields)

4. 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
lte
update(**kwargs)
Model metadata
distinct()

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

6. 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
Many-to-many relationship through an intermediate model
Abstract base class
only(*fields)
day

7. 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.
iendswith
pickling
Many-to-many relationship to self
choices tuple

8. A convenience method for constructing an object and saving it all in one step.
relationship spanning
Model metadata
get(**kwargs)
create(**kwargs)

9. Lookup type that returns results in a given list.
get(**kwargs)
class attributes
day
in

10. Lookup type that returns results that fall into an inclusive date range.
month
exists()
range
using(alias)

11. Exception raised by get(**kwargs) if no items match the query.
DoesNotExist
ForeignKey
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
Entry.objects.filter(pub_date__range=(start_date - end_date))

12. Lookup type for date/datetime fields that finds an exact month match. Takes an integer 1 (January) through 12
month
ManyToManyField
all()
F()

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

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

14. Lookup type for date/datetime fields that finds an exact year match. Takes a four-digit year.
year
Many-to-many relationship through an intermediate model
contains
get_or_create(**kwargs)

15. 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)
get_or_create(**kwargs)
QuerySet
pickling

16. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.
get(**kwargs)
lte
distinct()
iexact

17. To activate your models
select_related()
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
default
delete()

18. 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.
all()
filter chaining
update()
evaluation

19. If this option is True - Django will store empty values as NULL in the database. Default is False.
week_day
many-to-many relationship
null
help_text

20. Negation operator for Q objects.
create(**kwargs)
~
Multi-table inheritance
values_list(*fields)

21. 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

22. 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

23. 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
defer(*fields)
aggregate(args - *kwargs)
choices
search

24. (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
related_name
blank
QuerySet

25. Lookup type that returns results greater than a given value.
iterator()
gt
Manager methods
related_name

26. 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
many-to-one relationship
Many-to-many relationship to self
only(*fields)
defer(*fields)

27. Lookup type that returns results less than a given value.
week_day
Q(question__istartswith='What')
filter
lt

28. This query deletes all Entry objects with a pub_date year of 2005.
ForeignKey
Entry.objects.filter(pub_date__year=2005).delete()
get_or_create(**kwargs)
ManyToManyField

29. Lookup type for date/datetime fields that finds an exact day match.
OneToOneField
istartswith
day
get(**kwargs)

30. 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.
Entry.objects.filter(id__gt=4)
ForeignKey
class type
==

31. Returns a new QuerySet containing objects that match the given lookup parameters.
iregex
select_related()
regex
filter(**kwargs)

32. These add custom "row-level" functionality to your objects. These act on a particular model instance.
lte
Manager methods
create(**kwargs)
Custom model methods

33. 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
ForeignKey
MultipleObjectsReturned
evaluation

34. Lookup type that yields a case-insensitive match.
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
iexact
iendswith
get_absolute_url()

35. 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
Meta class
~
get_or_create(**kwargs)

36. Returns the object matching the given lookup parameters
blank
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
get(**kwargs)
F()

37. 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
contains
relationship spanning
choices
QuerySet

38. Keyword shortcut for looking up an object by primary key.
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
pk
choices
id field

39. Can be used to remove all many-to-many relationships for an instance
clear() method
delete()
DoesNotExist
all()

40. Returns the most recent object in the table - by date - using the field_name provided as the date field.
many-to-one relationship
ForeignKey
filter chaining
latest(field_name=None)

41. Fields are specified by these
class attributes
==
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
isnull

42. 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.
Many-to-many relationship through an intermediate model
Manager methods
regex
reverse name

43. This represents a collection of objects from your database. It can have zero - one or many filters.
QuerySet
ForeignKey
slicing
clear() method

44. This gives your model metadata.
help_text
using(alias)
Meta class
reverse name

45. If True - the table does not permit duplicate values for this field.
exclude(**kwargs)
delete()
Abstract base class
unique

46. 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
default
exists()
Restrictions on field names
week_day

47. 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

48. a QuerySet can be sliced - using Python's array-slicing syntax.
evaluation
Restrictions on field names
slicing
filter chaining

49. 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.
delete()
choices tuple
count()
gt

50. Lookup type that returns results less than or equal to a given value.
all()
related_name
null
lte