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Test your basic knowledge |
Django Queryset
Start Test
Study First
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. 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
relationship spanning
pickling
filter(**kwargs)
day
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.
exists()
|
Restrictions on field names
model
3. A Manager method that returns a new QuerySet containing objects that match the given lookup parameters.
Model metadata
filter(**kwargs)
contains
dates(field - kind - order='ASC')
4. Exception raised by get(**kwargs) if no items match the query.
DoesNotExist
update(**kwargs)
regex
in
5. 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.
relationship spanning
update()
iteration
select_related()
6. Returns a ValuesQuerySet -- a QuerySet that returns dictionaries when used as an iterable - rather than model-instance objects.
all()
delete()
values(*fields)
isnull
7. 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
defer(*fields)
lte
all()
exists()
8. Lookup type that returns results less than or equal to a given value.
update(**kwargs)
help_text
startswith
lte
9. 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.
Custom model methods
Many-to-many relationship to self
|
Entry.objects.filter(pub_date__year=2005).delete()
10. Returns the object matching the given lookup parameters
in_bulk(id_list)
get(**kwargs)
Proxy model
istartswith
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.
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
clear() method
values(*fields)
Many-to-many relationship to self
12. A Python "magic method" that returns a unicode "representation" of any object.
__unicode__()
filter chaining
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
13. Lookup type that returns results with a case-insensitive end sequence.
iendswith
QuerySet
through argument
delete()
14. 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
15. If this option is True - the field is allowed to be blank. Default is False.
Many-to-many relationship through an intermediate model
QuerySet
blank
null
16. Operator for comparing two model instances for equality. Behind the scenes - it compares the primary key values of two models.
==
QuerySet
update(**kwargs)
iexact
17. These add custom "row-level" functionality to your objects. These act on a particular model instance.
Custom model methods
in_bulk(id_list)
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
count()
18. 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
19. Can be used to remove all many-to-many relationships for an instance
range
defer(*fields)
clear() method
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
20. Disjunction operator for Q objects.
|
Meta class
Q()
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
21. If you are using this attribute on a ForeignKey or ManyToManyField - you must always specify a unique reverse name for the field.
istartswith
Many-to-many relationship to self
related_name
|
22. Lookup type that returns results greater than a given value.
annotate(args - *kwargs)
only(*fields)
gt
lt
23. 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.
blank
delete()
aggregate(args - *kwargs)
DoesNotExist
24. This query deletes all Entry objects with a pub_date year of 2005.
delete()
Entry.objects.filter(pub_date__year=2005).delete()
search
when you add new apps to INSTALLED_APPS
25. This query finds all entries with an id greater than 4.
Entry.objects.filter(id__gt=4)
year
intermediate models
DoesNotExist
26. 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()
iendswith
many-to-one relationship
id field
evaluation
27. Lookup type that yields a case-insensitive match.
through argument
save()
clear() method
iexact
28. A convenience method for looking up an object with the given kwargs - creating one if necessary.
dates(field - kind - order='ASC')
lt
class attributes
get_or_create(**kwargs)
29. 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.
id field
Model metadata
search
pickling
30. 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.
startswith
slicing
Q()
when you add new apps to INSTALLED_APPS
31. 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
Entry.objects.filter(pub_date__year=2005).delete()
Manager
through argument
update(**kwargs)
32. 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 through an intermediate model
help_text
MultipleObjectsReturned
ForeignKey
33. 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.
istartswith
ManyToManyField
Manager methods
Many-to-many relationship through an intermediate model
34. 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()
model
reverse()
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.
in
all()
order_by(*fields)
delete()
36. Lookup type that returns results that fall into an inclusive date range.
range
using(alias)
one-to-one relationship
values_list(*fields)
37. This method immediately deletes the object and has no return value.
delete()
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
Many-to-many relationship to self
filter
38. This method is for controlling which database the QuerySet will be evaluated against if you are using more than one database. The only argument this method takes is the alias of a database - as defined in DATABASES.
update()
~
Manager methods
using(alias)
39. If True - this field is the primary key for the model.
filter(**kwargs)
Manager
primary_key
defer(*fields)
40. 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
lt
when you add new apps to INSTALLED_APPS
iteration
41. 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()
filter(**kwargs)
Custom model methods
model
42. If this option is True - Django will store empty values as NULL in the database. Default is False.
null
range
gt
Field lookups
43. 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.
all()
DoesNotExist
reverse()
update(**kwargs)
44. A manager method which returns a single object. If there are no results that match the query - this method will raise a DoesNotExist exception. If more than one item matches this query - the method will raise MultipleObjectsReturned.
count()
day
relationship spanning
get(**kwargs)
45. This query finds all entries between a start date of start_date and an end date of end_date.
id field
search
Entry.objects.filter(pub_date__range=(start_date - end_date))
evaluation
46. 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
Field lookups
~
many-to-one relationship
47. Manager method used to retrieve every object in a model.
exists()
all()
==
count()
48. Fields are specified by these
class attributes
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
values_list(*fields)
choices
49. Lookup type for date/datetime fields that finds a 'day of the week' match.
iteration
add()
week_day
values(*fields)
50. 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.
iterator()
Restrictions on field names
pickling
create(**kwargs)