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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. The database that will be used if this query is executed now
values_list(*fields)
only(*fields)
db
week_day
2. Adds to each object in the QuerySet with the provided list of aggregate values (averages - sums - etc) that have been computed over the objects that are related to the objects in the QuerySet. Each argument to this is content that will be added to ea
Field lookups
annotate(args - *kwargs)
order_by(*fields)
delete()
3. This model method is used for updating a ManyToManyField.
get(**kwargs)
add()
range
pk
4. Returns an integer representing the number of objects in the database matching the QuerySet. This never raises exceptions.
range
count()
day
Q(question__istartswith='What')
5. 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
one-to-one relationship
get_or_create(**kwargs)
db
Abstract base class
6. If this option is True - the field is allowed to be blank. Default is False.
many-to-one relationship
ManyToManyField
Restrictions on field names
blank
7. Lookup type that returns results with a case-sensitive start sequence.
startswith
blank
values_list(*fields)
none()
8. 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.
when you add new apps to INSTALLED_APPS
filter chaining
iteration
endswith
9. Defined by a OneToOneField. You use it just like any other Field type: by including it as a class attribute of your model.
endswith
filter chaining
one-to-one relationship
using(alias)
10. 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.
reverse name
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
class type
OneToOneField
11. 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.
blank
reverse name
get(**kwargs)
Entry.objects.filter(id__gt=4)
12. Extra text to be displayed under the field on the object's admin form to provide assistance to users. It's useful for documentation even if your object doesn't have an admin form.
default
help_text
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
many-to-one relationship
13. Can be used to remove all many-to-many relationships for an instance
clear() method
values_list(*fields)
exclude(**kwargs)
__unicode__()
14. Used to get a QuerySet for a model. This is called 'objects' by default.
Manager
count()
distinct()
ordered
15. Lookup type for date/datetime fields that finds a 'day of the week' match.
regex
in_bulk(id_list)
week_day
Q(question__istartswith='What')
16. 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)
help_text
iendswith
using(alias)
Model metadata
17. 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.
update()
gt
pk
contains
18. Defined by a ManyToManyField. You use it just like any other Field type: by including it as a class attribute of your model.
many-to-many relationship
Entry.objects.filter(id__gt=4)
contains
day
19. Lookup type that returns results with a case-insensitive start sequence.
isnull
relationship spanning
Q(question__istartswith='What')
istartswith
20. The default for this is the name of the child class followed by '_set'.
reverse name
choices tuple
get_or_create(**kwargs)
gte
21. Lookup type that returns results less than or equal to a given value.
choices tuple
lte
Multi-table inheritance
aggregate(args - *kwargs)
22. This gives your model metadata.
search
Meta class
&
delete()
23. 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.
lte
choices
get_absolute_url()
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
24. If True - the table does not permit duplicate values for this field.
aggregate(args - *kwargs)
Restrictions on field names
unique
evaluation
25. 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
==
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
only(*fields)
iterator()
26. 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()
values(*fields)
get_absolute_url()
annotate(args - *kwargs)
27. 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.
endswith
annotate(args - *kwargs)
pickling
in_bulk(id_list)
28. 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
Entry.objects.filter(id__in=[1 - 3 - 4])
search
defer(*fields)
filter
29. A QuerySet is iterable - and it executes its database query the first time you iterate over it.
when you add new apps to INSTALLED_APPS
iteration
Many-to-many relationship to self
in
30. 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
__unicode__()
filter
istartswith
31. 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.
count()
choices tuple
__unicode__()
relationship spanning
32. 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
33. These add custom "row-level" functionality to your objects. These act on a particular model instance.
filter
Custom model methods
exclude(**kwargs)
~
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()
F()
class attributes
DoesNotExist
35. (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.
delete()
Restrictions on field names
month
db
36. A convenience method for looking up an object with the given kwargs - creating one if necessary.
get_or_create(**kwargs)
dates(field - kind - order='ASC')
Model metadata
get_absolute_url()
37. 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()
Q(question__istartswith='What')
id field
evaluation
Proxy model
38. If this option is True - Django will store empty values as NULL in the database. Default is False.
clear() method
null
filter(**kwargs)
|
39. This query finds all entries between a start date of start_date and an end date of end_date.
Entry.objects.filter(pub_date__year=2005).delete()
iteration
ManyToManyField
Entry.objects.filter(pub_date__range=(start_date - end_date))
40. 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
filter(**kwargs)
relationship spanning
Custom model methods
Many-to-many relationship to self
41. 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.
aggregate(args - *kwargs)
week_day
Restrictions on field names
order_by(*fields)
42. 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.
search
when you add new apps to INSTALLED_APPS
contains
choices tuple
43. Lookup type that returns results in a given list.
in
search
~
Many-to-many relationship through an intermediate model
44. Each one of these is a Python class that subclasses django.db.models.Model. Each attribute of one of these represents a database field.
gt
class attributes
model
&
45. Lookup type that finds a case-insensitive regular expression match.
Entry.objects.filter(pub_date__range=(start_date - end_date))
iregex
update()
Entry.objects.filter(id__gt=4)
46. Lookup type that returns results with a case-insensitive end sequence.
get(**kwargs)
iendswith
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
intermediate models
47. 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
many-to-many relationship
|
exists()
Q()
48. Manager method used to retrieve every object in a model.
add()
&
all()
range
49. 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
ordered
Model metadata
db
intermediate models
50. 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.
Proxy model
reverse()
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
Many-to-many relationship to self