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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 an EmptyQuerySet -- a QuerySet that always evaluates to an empty list. This can be used in cases where you know that you should return an empty result set and your caller is expecting a QuerySet object (instead of returning an empty list - fo
through argument
annotate(args - *kwargs)
dates(field - kind - order='ASC')
none()
2. Lookup type that takes either True or False and corresponds to SQL queries of IS NULL and IS NOT NULL - respectively.
many-to-many relationship
reverse name
isnull
pickling
3. 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
none()
exists()
in
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
4. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.
distinct()
update(**kwargs)
gt
iendswith
5. These add custom "row-level" functionality to your objects. These act on a particular model instance.
Custom model methods
|
reverse()
get_absolute_url()
6. 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.
week_day
id field
using(alias)
exists()
7. 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.
when you add new apps to INSTALLED_APPS
all()
exact
lt
8. This gives your model metadata.
filter
Meta class
Many-to-many relationship to self
order_by(*fields)
9. If this option is True - the field is allowed to be blank. Default is False.
id field
Manager methods
blank
delete()
10. 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
Entry.objects.filter(pub_date__year=2005).delete()
lt
Many-to-many relationship to self
relationship spanning
11. 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
dates(field - kind - order='ASC')
save()
intermediate models
Field lookups
12. Each one of these is a Python class that subclasses django.db.models.Model. Each attribute of one of these represents a database field.
default
model
__unicode__()
using(alias)
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
through argument
Meta class
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
related_name
14. Exception raised by get(**kwargs) if no items match the query.
DoesNotExist
search
regex
save()
15. 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.
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
aggregate(args - *kwargs)
Restrictions on field names
Entry.objects.filter(id__in=[1 - 3 - 4])
16. A convenience method for constructing an object and saving it all in one step.
week_day
filter
clear() method
create(**kwargs)
17. 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.
endswith
filter
search
many-to-many relationship
18. Manager method used to retrieve every object in a model.
help_text
only(*fields)
Restrictions on field names
all()
19. Lookup type that returns results with a case-insensitive start sequence.
OneToOneField
exists()
istartswith
many-to-many relationship
20. 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.
through argument
gte
get_absolute_url()
Many-to-many relationship to self
21. 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.
|
add()
isnull
choices tuple
22. This style of inheritanc is useful when you're subclassing an existing model (perhaps something from another application entirely) and want each model to have its own database table. Here - each model in the hierarchy is a model all by itself.
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
Multi-table inheritance
Many-to-many relationship through an intermediate model
==
23. 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.
ForeignKey
model
null
iregex
24. Lookup type that finds a case-insensitive regular expression match.
regex
many-to-one relationship
month
iregex
25. To activate your models
iteration
pickling
Multi-table inheritance
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
26. A Manager method that returns a new QuerySet containing objects that match the given lookup parameters.
filter(**kwargs)
slicing
Abstract base class
get_absolute_url()
27. Lookup type that returns results that fall into an inclusive date range.
filter chaining
range
distinct()
Multi-table inheritance
28. Returns a new QuerySet containing objects that match the given lookup parameters.
update(**kwargs)
one-to-one relationship
values_list(*fields)
filter(**kwargs)
29. 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
in_bulk(id_list)
annotate(args - *kwargs)
delete()
istartswith
30. 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.
filter
isnull
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
31. Disjunction operator for Q objects.
model
|
values_list(*fields)
exact
32. Lookup type that returns results greater than or equal to a given value.
lte
slicing
gte
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
33. Lookup type that tests for inclusion in a case-sensitive fashion.
reverse name
contains
choices
iendswith
34. Returns a ValuesQuerySet -- a QuerySet that returns dictionaries when used as an iterable - rather than model-instance objects.
latest(field_name=None)
choices
update()
values(*fields)
35. This query finds all entries between a start date of start_date and an end date of end_date.
filter
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
Entry.objects.filter(pub_date__range=(start_date - end_date))
MultipleObjectsReturned
36. Conjuntion operator for Q objects.
aggregate(args - *kwargs)
ForeignKey
&
OneToOneField
37. Lookup type that returns results less than or equal to a given value.
filter(**kwargs)
blank
filter
lte
38. 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()
istartswith
many-to-many relationship
OneToOneField
39. A convenience method for looking up an object with the given kwargs - creating one if necessary.
filter
Custom model methods
get_or_create(**kwargs)
ManyToManyField
40. The database that will be used if this query is executed now
db
evaluation
get_absolute_url()
contains
41. 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
42. This is a criterion that narrow down a QuerySet based on given parameters.
filter
reverse()
annotate(args - *kwargs)
update(**kwargs)
43. Fields are specified by these
when you add new apps to INSTALLED_APPS
reverse name
gt
class attributes
44. This model method is used for updating a ManyToManyField.
add()
startswith
update()
search
45. Lookup type that returns results with a case-sensitive end sequence.
&
annotate(args - *kwargs)
endswith
istartswith
46. Operator for comparing two model instances for equality. Behind the scenes - it compares the primary key values of two models.
exists()
db
isnull
==
47. Returns the object matching the given lookup parameters
get(**kwargs)
only(*fields)
ForeignKey
class attributes
48. A Python "magic method" that returns a unicode "representation" of any object.
Restrictions on field names
Manager
__unicode__()
in
49. 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
50. The value given in the absence of a specified value for the field. This can be a value or a callable object. If callable it will be called every time a new object is created.
Proxy model
default
select_related()
Q(question__startswith='Who') | ~Q(pub_date__year=2005)