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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 Manager method that returns a new QuerySet containing objects that match the given lookup parameters.
Q(question__istartswith='What')
intermediate models
filter(**kwargs)
one-to-one relationship
2. These are specified as keyword arguments to the QuerySet methods filter() - exclude() and get(). These take the form field__lookuptype=value .
id field
filter(**kwargs)
day
Field lookups
3. 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
class type
delete()
ordered
intermediate models
4. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.
distinct()
filter chaining
slicing
unique
5. When to run syncdb
ManyToManyField
when you add new apps to INSTALLED_APPS
update(**kwargs)
day
6. 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
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
all()
regex
7. If True - this field is the primary key for the model.
primary_key
pickling
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
MultipleObjectsReturned
8. Lookup type that yields a case-insensitive match.
aggregate(args - *kwargs)
iexact
intermediate models
range
9. This query finds all entries with an id in the list [1 - 3 - 4]
Entry.objects.filter(id__in=[1 - 3 - 4])
choices tuple
Entry.objects.filter(id__gt=4)
get(**kwargs)
10. This model method saves a model instance to the database. This method has no return value.
primary_key
count()
save()
Entry.objects.filter(id__in=[1 - 3 - 4])
11. 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
in
using(alias)
all()
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
12. Keyword shortcut for looking up an object by primary key.
pk
using(alias)
many-to-many relationship
regex
13. Fields are specified by these
class attributes
distinct()
many-to-many relationship
blank
14. 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)
exact
istartswith
isnull
Model metadata
15. 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.
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
exact
Entry.objects.filter(id__gt=4)
Proxy model
16. This field is added automatically - but this behavior can be overridden
year
defer(*fields)
primary_key
id field
17. If this option is True - Django will store empty values as NULL in the database. Default is False.
==
null
Entry.objects.filter(id__in=[1 - 3 - 4])
delete()
18. This method returns tuples of values when iterated over. Each tuple contains the value from the respective field passed into the call to this method -- so the first item is the first field - etc.
values_list(*fields)
many-to-many relationship
get(**kwargs)
Proxy model
19. Lookup type that returns results less than or equal to a given value.
all()
lte
F()
pickling
20. Disjunction operator for Q objects.
get(**kwargs)
model
intermediate models
|
21. 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.
relationship spanning
select_related()
delete()
Custom model methods
22. 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.
Restrictions on field names
exact
ordered
ForeignKey
23. A QuerySet is iterable - and it executes its database query the first time you iterate over it.
==
iteration
exists()
select_related()
24. 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
year
clear() method
ordered
25. Lookup type that returns results with a case-sensitive end sequence.
Q()
endswith
annotate(args - *kwargs)
filter(**kwargs)
26. 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
lt
update(**kwargs)
27. If this option is True - the field is allowed to be blank. Default is False.
lt
blank
month
Proxy model
28. 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
contains
MultipleObjectsReturned
Entry.objects.filter(id__gt=4)
iterator()
29. Lookup type that returns results with a case-sensitive start sequence.
many-to-many relationship
|
pk
startswith
30. 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.
OneToOneField
choices
iteration
class type
31. 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
gte
istartswith
filter(**kwargs)
defer(*fields)
32. 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.
month
ForeignKey
Custom model methods
get(**kwargs)
33. A convenience method for looking up an object with the given kwargs - creating one if necessary.
annotate(args - *kwargs)
~
get_or_create(**kwargs)
&
34. This method immediately deletes the object and has no return value.
Entry.objects.filter(pub_date__year=2005).delete()
Entry.objects.filter(id__in=[1 - 3 - 4])
delete()
contains
35. 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.
many-to-one relationship
help_text
aggregate(args - *kwargs)
create(**kwargs)
36. 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.
Multi-table inheritance
ManyToManyField
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
values(*fields)
37. 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.
in_bulk(id_list)
save()
search
model
38. 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.
reverse()
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
Many-to-many relationship to self
choices tuple
39. 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
one-to-one relationship
help_text
ordered
40. 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
41. Returns the most recent object in the table - by date - using the field_name provided as the date field.
Multi-table inheritance
Meta class
help_text
latest(field_name=None)
42. A convenience method for constructing an object and saving it all in one step.
create(**kwargs)
gt
update()
delete()
43. 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()
Proxy model
evaluation
&
44. Lookup type that returns results that fall into an inclusive date range.
Entry.objects.filter(id__gt=4)
intermediate models
range
blank
45. 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))
values_list(*fields)
db
unique
46. 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.
istartswith
search
Restrictions on field names
pk
47. Lookup type that finds a case-sensitive regular expression match.
regex
clear() method
exclude(**kwargs)
delete()
48. 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.
ManyToManyField
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
choices tuple
Q()
49. Lookup type that returns results greater than or equal to a given value.
gte
Entry.objects.filter(pub_date__year=2005).delete()
delete()
Model metadata
50. 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
filter(**kwargs)
Restrictions on field names
F()
Q(question__startswith='Who') | ~Q(pub_date__year=2005)