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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. 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
exists()
F()
regex
gt
2. Keyword shortcut for looking up an object by primary key.
many-to-one relationship
none()
pickling
pk
3. This model method is used for updating a ManyToManyField.
add()
Entry.objects.filter(id__gt=4)
update()
Model metadata
4. A QuerySet is iterable - and it executes its database query the first time you iterate over it.
==
&
iteration
istartswith
5. Lookup type that returns results with a case-insensitive end sequence.
iendswith
Field lookups
day
Entry.objects.filter(pub_date__year=2005).delete()
6. 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.
pickling
blank
choices
aggregate(args - *kwargs)
7. Returns the most recent object in the table - by date - using the field_name provided as the date field.
lte
Many-to-many relationship to self
latest(field_name=None)
week_day
8. 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
relationship spanning
pk
day
9. 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.
Q()
choices tuple
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
10. 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
id field
year
Entry.objects.filter(id__in=[1 - 3 - 4])
iterator()
11. Returns a ValuesQuerySet -- a QuerySet that returns dictionaries when used as an iterable - rather than model-instance objects.
values(*fields)
Q()
evaluation
==
12. This model type is useful if you only want to modify the Python-level behavior of a model - without changing the models fields in any way. This creates a stand-in for the original model. You can create - delete and update instances of this new model
Proxy model
relationship spanning
ForeignKey
update(**kwargs)
13. 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
year
iterator()
through argument
save()
14. 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.
count()
F()
DoesNotExist
update()
15. 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
istartswith
Proxy model
Field lookups
intermediate models
16. Lookup type that returns results with a case-insensitive start sequence.
isnull
update(**kwargs)
istartswith
endswith
17. Lookup type for date/datetime fields that finds an exact month match. Takes an integer 1 (January) through 12
month
get(**kwargs)
Multi-table inheritance
related_name
18. Returns a new QuerySet containing objects that match the given lookup parameters.
add()
filter(**kwargs)
Manager methods
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
19. This query finds all entries with an id in the list [1 - 3 - 4]
get_or_create(**kwargs)
Entry.objects.filter(id__in=[1 - 3 - 4])
filter
Restrictions on field names
20. Lookup type that takes either True or False and corresponds to SQL queries of IS NULL and IS NOT NULL - respectively.
filter
iterator()
only(*fields)
isnull
21. 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
create(**kwargs)
null
year
Abstract base class
22. 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.
get_or_create(**kwargs)
when you add new apps to INSTALLED_APPS
select_related()
choices tuple
23. Conjuntion operator for Q objects.
filter(**kwargs)
DoesNotExist
&
range
24. Operator for comparing two model instances for equality. Behind the scenes - it compares the primary key values of two models.
==
exact
range
get_absolute_url()
25. Fields are specified by these
clear() method
get(**kwargs)
class attributes
unique
26. 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
27. 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.
month
ForeignKey
slicing
count()
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. This query deletes all Entry objects with a pub_date year of 2005.
Entry.objects.filter(pub_date__year=2005).delete()
iterator()
relationship spanning
one-to-one relationship
30. This is a criterion that narrow down a QuerySet based on given parameters.
Abstract base class
month
filter
values(*fields)
31. 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
Q()
&
ordered
class type
32. The database that will be used if this query is executed now
latest(field_name=None)
db
count()
Manager
33. 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.
delete()
Many-to-many relationship to self
get(**kwargs)
Proxy model
34. Returns a copy of the current QuerySet (or QuerySet subclass you pass in). This can be useful in some situations where you might want to pass in either a model manager or a QuerySet and do further filtering on the result. You can safely call all() on
Meta class
year
week_day
all()
35. Can be used to remove all many-to-many relationships for an instance
add()
clear() method
Model metadata
filter(**kwargs)
36. 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.
order_by(*fields)
exists()
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
get_absolute_url()
37. If True - this field is the primary key for the model.
evaluation
Q()
primary_key
class type
38. Lookup type that returns results less than or equal to a given value.
get_absolute_url()
class type
lte
OneToOneField
39. 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.
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
search
Q(question__istartswith='What')
using(alias)
40. 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
41. This gives your model metadata.
db
intermediate models
gte
Meta class
42. This method immediately deletes the object and has no return value.
intermediate models
in_bulk(id_list)
delete()
exclude(**kwargs)
43. Lookup type that finds a case-sensitive regular expression match.
regex
all()
search
id field
44. 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.
annotate(args - *kwargs)
Manager methods
search
ordered
45. This model method saves a model instance to the database. This method has no return value.
add()
save()
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
ordered
46. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.
ordered
select_related()
iregex
get_or_create(**kwargs)
47. Exception raised by get(**kwargs) if more than one item matches the query.
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
clear() method
Custom model methods
MultipleObjectsReturned
48. 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.
range
choices
isnull
in_bulk(id_list)
49. (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.
~
week_day
Restrictions on field names
create(**kwargs)
50. Each one of these is a Python class that subclasses django.db.models.Model. Each attribute of one of these represents a database field.
only(*fields)
endswith
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
model