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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. A Python "magic method" that returns a unicode "representation" of any object.
Custom model methods
__unicode__()
Model metadata
year
2. 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
F()
Entry.objects.filter(pub_date__range=(start_date - end_date))
annotate(args - *kwargs)
filter chaining
3. Lookup type that returns results greater than or equal to a given value.
regex
gte
iteration
aggregate(args - *kwargs)
4. 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.
many-to-one relationship
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
aggregate(args - *kwargs)
help_text
5. If True - the table does not permit duplicate values for this field.
clear() method
primary_key
unique
only(*fields)
6. Disjunction operator for Q objects.
id field
gt
only(*fields)
|
7. 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
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
Proxy model
Q(question__istartswith='What')
lte
8. A manager method that returns a new QuerySet containing objects that do not match the given lookup parameters.
get_or_create(**kwargs)
exclude(**kwargs)
delete()
save()
9. 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.
lt
ordered
Entry.objects.filter(pub_date__year=2005).delete()
in_bulk(id_list)
10. 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()
select_related()
blank
using(alias)
11. 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.
Entry.objects.filter(pub_date__year=2005).delete()
Many-to-many relationship through an intermediate model
gte
MultipleObjectsReturned
12. 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.
relationship spanning
Many-to-many relationship to self
exclude(**kwargs)
lt
13. 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()
pk
QuerySet
all()
evaluation
14. Manager method used to retrieve every object in a model.
QuerySet
DoesNotExist
all()
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
15. Lookup type that returns results less than or equal to a given value.
many-to-many relationship
order_by(*fields)
lte
one-to-one relationship
16. This is a criterion that narrow down a QuerySet based on given parameters.
lte
filter
lt
delete()
17. 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
Abstract base class
intermediate models
null
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
18. 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
19. Operator for comparing two model instances for equality. Behind the scenes - it compares the primary key values of two models.
filter(**kwargs)
choices tuple
create(**kwargs)
==
20. Can be used to remove all many-to-many relationships for an instance
clear() method
__unicode__()
filter(**kwargs)
in
21. 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.
filter
model
day
get_absolute_url()
22. 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.
none()
using(alias)
Field lookups
iendswith
23. 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.
Q(question__istartswith='What')
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
Meta class
default
24. 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
isnull
search
through argument
filter chaining
25. This gives your model metadata.
iterator()
F()
Meta class
through argument
26. The database that will be used if this query is executed now
db
Q(question__istartswith='What')
Meta class
week_day
27. This query finds all entries with an id in the list [1 - 3 - 4]
when you add new apps to INSTALLED_APPS
day
update(**kwargs)
Entry.objects.filter(id__in=[1 - 3 - 4])
28. A convenience method for looking up an object with the given kwargs - creating one if necessary.
Entry.objects.filter(pub_date__year=2005).delete()
get_or_create(**kwargs)
get(**kwargs)
Proxy model
29. Lookup type for date/datetime fields that finds a 'day of the week' match.
year
Abstract base class
week_day
reverse name
30. a QuerySet can be sliced - using Python's array-slicing syntax.
&
relationship spanning
slicing
iterator()
31. 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.
evaluation
Manager methods
reverse()
Meta class
32. These methods are intended to do "table-wide" things.
|
reverse name
ManyToManyField
Manager methods
33. 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.
filter(**kwargs)
update()
OneToOneField
default
34. Used to get a QuerySet for a model. This is called 'objects' by default.
lte
values_list(*fields)
aggregate(args - *kwargs)
Manager
35. Returns a new QuerySet containing objects that match the given lookup parameters.
filter(**kwargs)
istartswith
contains
pk
36. 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
Restrictions on field names
iterator()
none()
month
37. 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.
relationship spanning
one-to-one relationship
filter chaining
intermediate models
38. 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.
distinct()
values(*fields)
many-to-one relationship
reverse()
39. Returns a ValuesQuerySet -- a QuerySet that returns dictionaries when used as an iterable - rather than model-instance objects.
Q(question__istartswith='What')
values(*fields)
default
exclude(**kwargs)
40. This query finds all entries between a start date of start_date and an end date of end_date.
exists()
&
Entry.objects.filter(pub_date__range=(start_date - end_date))
~
41. Returns the most recent object in the table - by date - using the field_name provided as the date field.
latest(field_name=None)
get_absolute_url()
clear() method
select_related()
42. Returns an integer representing the number of objects in the database matching the QuerySet. This never raises exceptions.
count()
lte
create(**kwargs)
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
43. 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.
annotate(args - *kwargs)
exists()
values(*fields)
get(**kwargs)
44. 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()
slicing
OneToOneField
Field lookups
45. Fields are specified by these
contains
Field lookups
blank
class attributes
46. Lookup type for date/datetime fields that finds an exact month match. Takes an integer 1 (January) through 12
values(*fields)
month
choices tuple
db
47. Lookup type that yields a case-insensitive match.
iexact
db
Model metadata
get_absolute_url()
48. 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
class type
ManyToManyField
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
49. 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
Q(question__istartswith='What')
year
all()
get_absolute_url()
50. These add custom "row-level" functionality to your objects. These act on a particular model instance.
F()
update()
Model metadata
Custom model methods