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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. 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
iregex
month
only(*fields)
get(**kwargs)
2. This is a criterion that narrow down a QuerySet based on given parameters.
when you add new apps to INSTALLED_APPS
filter
values(*fields)
get(**kwargs)
3. 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.
year
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
ForeignKey
&
4. Used to get a QuerySet for a model. This is called 'objects' by default.
Proxy model
primary_key
Manager
Manager methods
5. 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
iteration
intermediate models
model
class attributes
6. 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.
Restrictions on field names
many-to-one relationship
in
distinct()
7. Lookup type that returns results with a case-insensitive start sequence.
istartswith
regex
iexact
using(alias)
8. Exception raised by get(**kwargs) if no items match the query.
add()
Restrictions on field names
filter(**kwargs)
DoesNotExist
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.
Many-to-many relationship to self
Custom model methods
endswith
Abstract base class
10. 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.
only(*fields)
filter chaining
Many-to-many relationship to self
isnull
11. Lookup type that returns results with a case-sensitive start sequence.
Field lookups
get_absolute_url()
many-to-one relationship
startswith
12. 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
13. Lookup type for date/datetime fields that finds an exact day match.
search
delete()
day
defer(*fields)
14. 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.
distinct()
relationship spanning
startswith
order_by(*fields)
15. If you are using this attribute on a ForeignKey or ManyToManyField - you must always specify a unique reverse name for the field.
id field
exact
Many-to-many relationship to self
related_name
16. Manager method used to retrieve every object in a model.
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
all()
gte
endswith
17. 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
18. 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.
Entry.objects.filter(pub_date__year=2005).delete()
OneToOneField
Many-to-many relationship to self
iterator()
19. Lookup type that takes either True or False and corresponds to SQL queries of IS NULL and IS NOT NULL - respectively.
save()
update()
filter(**kwargs)
isnull
20. A convenience method for looking up an object with the given kwargs - creating one if necessary.
none()
get_or_create(**kwargs)
related_name
Q(question__istartswith='What')
21. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.
null
reverse()
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
distinct()
22. Lookup type that tests for inclusion in a case-sensitive fashion.
contains
DoesNotExist
through argument
gte
23. Returns a ValuesQuerySet -- a QuerySet that returns dictionaries when used as an iterable - rather than model-instance objects.
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
create(**kwargs)
istartswith
values(*fields)
24. If this option is True - the field is allowed to be blank. Default is False.
~
blank
filter(**kwargs)
get(**kwargs)
25. 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.
exact
Q()
Entry.objects.filter(pub_date__range=(start_date - end_date))
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
26. This field is added automatically - but this behavior can be overridden
pk
id field
ForeignKey
startswith
27. 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.
pickling
iterator()
day
filter(**kwargs)
28. Each one of these is a Python class that subclasses django.db.models.Model. Each attribute of one of these represents a database field.
many-to-one relationship
get_absolute_url()
ManyToManyField
model
29. Exception raised by get(**kwargs) if more than one item matches the query.
through argument
reverse name
Model metadata
MultipleObjectsReturned
30. 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()
in
DoesNotExist
relationship spanning
31. 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.
aggregate(args - *kwargs)
==
only(*fields)
reverse()
32. Can be used to remove all many-to-many relationships for an instance
through argument
clear() method
null
istartswith
33. If True - this field is the primary key for the model.
update(**kwargs)
primary_key
month
year
34. Lookup type for date/datetime fields that finds an exact month match. Takes an integer 1 (January) through 12
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
year
relationship spanning
month
35. 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.
unique
get_absolute_url()
save()
contains
36. 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.
lt
ordered
regex
Many-to-many relationship through an intermediate model
37. When to run syncdb
&
week_day
when you add new apps to INSTALLED_APPS
Manager
38. 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)
Model metadata
reverse name
ForeignKey
all()
39. Lookup type that returns results in a given list.
Model metadata
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
delete()
in
40. This represents a collection of objects from your database. It can have zero - one or many filters.
OneToOneField
QuerySet
lte
ForeignKey
41. Fields are specified by these
Manager methods
class attributes
latest(field_name=None)
Restrictions on field names
42. These add custom "row-level" functionality to your objects. These act on a particular model instance.
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
save()
in_bulk(id_list)
Custom model methods
43. 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
44. If this option is True - Django will store empty values as NULL in the database. Default is False.
get_absolute_url()
Many-to-many relationship through an intermediate model
Entry.objects.filter(id__gt=4)
null
45. 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
Custom model methods
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
reverse()
iterator()
46. This object allows you to compare the value of a model field with another field on the same model. Django supports the use of addition - subtraction - multiplication - division and modulo arithmetic with these objects - both with constants and with o
blank
F()
regex
using(alias)
47. Defined by a OneToOneField. You use it just like any other Field type: by including it as a class attribute of your model.
one-to-one relationship
F()
isnull
istartswith
48. To activate your models
unique
exists()
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
DoesNotExist
49. This gives your model metadata.
==
Meta class
slicing
select_related()
50. 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.
reverse()
MultipleObjectsReturned
update()
year