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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. Defines a many-to-many relationship. You use it just like any other Field type: by including it as a class attribute of your model.
defer(*fields)
filter(**kwargs)
when you add new apps to INSTALLED_APPS
ManyToManyField
2. This model method saves a model instance to the database. This method has no return value.
save()
delete()
Many-to-many relationship through an intermediate model
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
3. Lookup type that returns results with a case-insensitive start sequence.
range
istartswith
filter
ordered
4. 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.
QuerySet
Many-to-many relationship through an intermediate model
values(*fields)
Field lookups
5. 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
db
lte
get(**kwargs)
select_related()
6. 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.
Custom model methods
choices
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
gt
7. 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()
evaluation
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
save()
latest(field_name=None)
8. 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
annotate(args - *kwargs)
filter(**kwargs)
primary_key
Many-to-many relationship to self
9. The database that will be used if this query is executed now
when you add new apps to INSTALLED_APPS
db
gt
delete()
10. 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.
primary_key
exact
slicing
gte
11. This is a criterion that narrow down a QuerySet based on given parameters.
QuerySet
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
filter
values(*fields)
12. Negation operator for Q objects.
null
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
DoesNotExist
~
13. 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
Abstract base class
db
istartswith
get(**kwargs)
14. 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(question__istartswith='What')
Field lookups
reverse name
class type
15. 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
iterator()
unique
range
16. 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
null
through argument
reverse name
get(**kwargs)
17. Returns an integer representing the number of objects in the database matching the QuerySet. This never raises exceptions.
slicing
year
count()
none()
18. Lookup type that finds a case-insensitive regular expression match.
in_bulk(id_list)
iregex
annotate(args - *kwargs)
Entry.objects.filter(pub_date__range=(start_date - end_date))
19. This model method is used for updating a ManyToManyField.
ForeignKey
Entry.objects.filter(id__in=[1 - 3 - 4])
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
add()
20. 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.
gt
search
one-to-one relationship
pk
21. 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
all()
iregex
none()
iendswith
22. This query finds all entries between a start date of start_date and an end date of end_date.
Entry.objects.filter(pub_date__range=(start_date - end_date))
startswith
|
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
23. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.
one-to-one relationship
DoesNotExist
distinct()
Meta class
24. Lookup type that returns results less than a given value.
count()
in_bulk(id_list)
iterator()
lt
25. 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
only(*fields)
update(**kwargs)
db
filter
26. Lookup type for date/datetime fields that finds an exact month match. Takes an integer 1 (January) through 12
update()
lte
through argument
month
27. Lookup type that yields a case-insensitive match.
ordered
many-to-many relationship
values(*fields)
iexact
28. 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
29. 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.
range
delete()
lte
Q()
30. This query finds all entries with an id in the list [1 - 3 - 4]
get_absolute_url()
iterator()
Entry.objects.filter(id__in=[1 - 3 - 4])
~
31. 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
model
none()
Q()
update(**kwargs)
32. 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
filter
DoesNotExist
endswith
33. Lookup type that returns results greater than a given value.
reverse name
Restrictions on field names
relationship spanning
gt
34. A convenience method for constructing an object and saving it all in one step.
add()
get(**kwargs)
create(**kwargs)
filter(**kwargs)
35. Defined by a ManyToManyField. You use it just like any other Field type: by including it as a class attribute of your model.
week_day
help_text
many-to-many relationship
all()
36. If True - this field is the primary key for the model.
reverse name
primary_key
many-to-many relationship
exists()
37. Lookup type that finds a case-sensitive regular expression match.
regex
get(**kwargs)
Entry.objects.filter(id__in=[1 - 3 - 4])
Manager
38. Lookup type that returns results with a case-insensitive end sequence.
get_or_create(**kwargs)
regex
annotate(args - *kwargs)
iendswith
39. 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
class type
exact
~
F()
40. 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.
filter chaining
blank
annotate(args - *kwargs)
day
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. 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()
relationship spanning
Many-to-many relationship to self
null
43. Used to get a QuerySet for a model. This is called 'objects' by default.
OneToOneField
choices
Manager
ForeignKey
44. 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)
ManyToManyField
exclude(**kwargs)
values(*fields)
45. (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.
range
Restrictions on field names
all()
search
46. This gives your model metadata.
annotate(args - *kwargs)
~
Field lookups
Meta class
47. 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.
count()
one-to-one relationship
default
lte
48. 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.
exact
Multi-table inheritance
defer(*fields)
iendswith
49. Lookup type that returns results that fall into an inclusive date range.
all()
default
range
values(*fields)
50. a QuerySet can be sliced - using Python's array-slicing syntax.
Q(question__istartswith='What')
isnull
slicing
QuerySet