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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. 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
Proxy model
~
2. Performs an SQL update query for the specified fields - and returns the number of rows affected. This method is applied instantly and the only restriction on the QuerySet that is updated is that it can only update columns in the model's main table. F
help_text
~
in_bulk(id_list)
update(**kwargs)
3. This model method is used for updating a ManyToManyField.
add()
iregex
iexact
Q(question__istartswith='What')
4. This query deletes all Entry objects with a pub_date year of 2005.
search
Entry.objects.filter(pub_date__year=2005).delete()
default
dates(field - kind - order='ASC')
5. 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.
related_name
QuerySet
Entry.objects.filter(id__gt=4)
reverse()
6. 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.
Custom model methods
exact
year
Field lookups
7. When to run syncdb
values(*fields)
when you add new apps to INSTALLED_APPS
filter chaining
class attributes
8. A convenience method for looking up an object with the given kwargs - creating one if necessary.
delete()
get_or_create(**kwargs)
get(**kwargs)
lte
9. 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
10. If True - this field is the primary key for the model.
QuerySet
primary_key
add()
MultipleObjectsReturned
11. This method immediately deletes the object and has no return value.
iteration
related_name
year
delete()
12. Lookup type that returns results in a given list.
select_related()
Many-to-many relationship to self
in
annotate(args - *kwargs)
13. Exception raised by get(**kwargs) if no items match the query.
get_or_create(**kwargs)
Restrictions on field names
DoesNotExist
exclude(**kwargs)
14. Used to get a QuerySet for a model. This is called 'objects' by default.
model
Model metadata
F()
Manager
15. Lookup type for date/datetime fields that finds an exact month match. Takes an integer 1 (January) through 12
month
using(alias)
exact
filter
16. 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
17. Lookup type that returns results with a case-sensitive end sequence.
dates(field - kind - order='ASC')
endswith
Manager
__unicode__()
18. A convenience method for constructing an object and saving it all in one step.
defer(*fields)
primary_key
filter(**kwargs)
create(**kwargs)
19. 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.
get_absolute_url()
lte
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
Restrictions on field names
20. (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.
iteration
gte
update(**kwargs)
Restrictions on field names
21. Lookup type that finds a case-insensitive regular expression match.
search
get(**kwargs)
day
iregex
22. 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.
Manager methods
latest(field_name=None)
values(*fields)
get(**kwargs)
23. Manager method used to retrieve every object in a model.
null
DoesNotExist
all()
intermediate models
24. If this option is True - Django will store empty values as NULL in the database. Default is False.
null
filter chaining
filter(**kwargs)
many-to-many relationship
25. Lookup type for date/datetime fields that finds an exact year match. Takes a four-digit year.
iexact
year
Entry.objects.filter(id__gt=4)
using(alias)
26. Lookup type that returns results greater than or equal to a given value.
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
Restrictions on field names
gte
OneToOneField
27. 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
iexact
filter
select_related()
Model metadata
28. Defined by a ManyToManyField. You use it just like any other Field type: by including it as a class attribute of your model.
Abstract base class
choices
many-to-many relationship
all()
29. If you pickle a QuerySet - this will force all the results to be loaded into memory prior to pickling. When you unpickle a QuerySet - it contains the results at the moment it was pickled - rather than the results that are currently in the database.
pickling
dates(field - kind - order='ASC')
startswith
choices
30. 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.
istartswith
gte
Q(question__istartswith='What')
delete()
31. A QuerySet is iterable - and it executes its database query the first time you iterate over it.
null
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
intermediate models
iteration
32. 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
annotate(args - *kwargs)
==
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
all()
33. 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(*fields)
values_list(*fields)
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
create(**kwargs)
34. Lookup type that yields a case-insensitive match.
__unicode__()
only(*fields)
count()
iexact
35. Lookup type that tests for inclusion in a case-sensitive fashion.
update(**kwargs)
filter(**kwargs)
contains
default
36. A Q object that asks for entries with a question value that start with 'Who' or do not have a publication date of 2005.
Warning
: Invalid argument supplied for foreach() in
/var/www/html/basicversity.com/show_quiz.php
on line
183
37. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.
ordered
aggregate(args - *kwargs)
Entry.objects.filter(pub_date__range=(start_date - end_date))
add()
38. This query finds all entries between a start date of start_date and an end date of end_date.
primary_key
Entry.objects.filter(pub_date__range=(start_date - end_date))
Custom model methods
lt
39. This field is added automatically - but this behavior can be overridden
id field
iendswith
istartswith
relationship spanning
40. 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.
class attributes
clear() method
help_text
order_by(*fields)
41. 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)
relationship spanning
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
latest(field_name=None)
42. 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
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
values_list(*fields)
Restrictions on field names
iterator()
43. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.
distinct()
none()
MultipleObjectsReturned
blank
44. 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)
Model metadata
endswith
save()
relationship spanning
45. This query finds all entries with an id in the list [1 - 3 - 4]
Entry.objects.filter(id__in=[1 - 3 - 4])
year
ordered
Many-to-many relationship to self
46. 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
intermediate models
filter(**kwargs)
order_by(*fields)
using(alias)
47. Returns the most recent object in the table - by date - using the field_name provided as the date field.
latest(field_name=None)
Custom model methods
year
week_day
48. This gives your model metadata.
Meta class
iterator()
distinct()
F()
49. Lookup type that returns results greater than a given value.
gt
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
Field lookups
dates(field - kind - order='ASC')
50. 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
filter
save()