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Django Queryset

Subject : it-skills

Instructions:

Answer 50 questions in 15 minutes.
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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. 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
relationship spanning
Meta class
exists()
unique

2. 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()
select_related()
distinct()
all()

3. a QuerySet can be sliced - using Python's array-slicing syntax.
get(**kwargs)
slicing
defer(*fields)
Proxy model

4. Lookup type that returns results with a case-sensitive end sequence.
endswith
get(**kwargs)
blank
get_or_create(**kwargs)

5. 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.
gt
Manager methods
ForeignKey
evaluation

6. 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
only(*fields)
Entry.objects.filter(pub_date__range=(start_date - end_date))
filter chaining
class type

7. 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.
ordered
reverse()
values(*fields)
get_absolute_url()

8. Returns the object matching the given lookup parameters
get(**kwargs)
evaluation
through argument
pk

9. Can be used to remove all many-to-many relationships for an instance
pk
clear() method
primary_key
db

10. This gives your model metadata.
get(**kwargs)
Meta class
evaluation
week_day

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')
OneToOneField
intermediate models
in_bulk(id_list)

12. 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.
search
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
week_day
&

13. 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.
DoesNotExist
using(alias)
exclude(**kwargs)
Restrictions on field names

14. 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
select_related()
iterator()
Entry.objects.filter(pub_date__year=2005).delete()
exclude(**kwargs)

15. A Manager method that returns a new QuerySet containing objects that match the given lookup parameters.
default
contains
filter(**kwargs)
iendswith

16. 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.
lte
delete()
values_list(*fields)
iendswith

17. 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
only(*fields)
defer(*fields)
Custom model methods
Many-to-many relationship to self

18. Lookup type that takes either True or False and corresponds to SQL queries of IS NULL and IS NOT NULL - respectively.
Q(question__istartswith='What')
get(**kwargs)
isnull
Many-to-many relationship to self

19. 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.
delete()
reverse()
pk
Meta class

20. 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
using(alias)
get_absolute_url()
all()
Meta class

21. Operator for comparing two model instances for equality. Behind the scenes - it compares the primary key values of two models.
==
many-to-one relationship
Many-to-many relationship to self
~

22. Fields are specified by these
class attributes
primary_key
Many-to-many relationship to self
istartswith

23. The default for this is the name of the child class followed by '_set'.
Multi-table inheritance
reverse name
year
Many-to-many relationship to self

24. Lookup type that finds a case-sensitive regular expression match.
regex
iteration
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
gte

25. 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

26. If this option is True - the field is allowed to be blank. Default is False.
blank
Manager
get(**kwargs)
ForeignKey

27. If True - this field is the primary key for the model.
primary_key
update()
Manager methods
add()

28. If you are using this attribute on a ForeignKey or ManyToManyField - you must always specify a unique reverse name for the field.
Entry.objects.filter(pub_date__range=(start_date - end_date))
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
related_name
all()

29. 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
ordered
iterator()
related_name
in_bulk(id_list)

30. 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
latest(field_name=None)
Abstract base class
none()
filter chaining

31. 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
OneToOneField
through argument
filter(**kwargs)
reverse name

32. This method immediately deletes the object and has no return value.
delete()
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
Proxy model
filter

33. 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.
through argument
update(**kwargs)
aggregate(args - *kwargs)
primary_key

34. This model method saves a model instance to the database. This method has no return value.
filter chaining
save()
class type
Manager methods

35. 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()
day
evaluation
Meta class
F()

36. Lookup type that returns results in a given list.
in
isnull
default
F()

37. This query finds all entries with an id in the list [1 - 3 - 4]
|
Entry.objects.filter(id__in=[1 - 3 - 4])
filter(**kwargs)
annotate(args - *kwargs)

38. The database that will be used if this query is executed now
db
all()
clear() method
annotate(args - *kwargs)

39. When to run syncdb
Entry.objects.filter(id__in=[1 - 3 - 4])
when you add new apps to INSTALLED_APPS
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
iregex

40. Negation operator for Q objects.
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
Q()
OneToOneField
~

41. Lookup type that returns results that fall into an inclusive date range.
range
iendswith
through argument
Field lookups

42. A manager method that returns a new QuerySet containing objects that do not match the given lookup parameters.
Abstract base class
exclude(**kwargs)
unique
null

43. 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
MultipleObjectsReturned
F()
iterator()
order_by(*fields)

44. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.
Q()
Multi-table inheritance
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
ordered

45. 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.
endswith
Multi-table inheritance
get(**kwargs)
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.

46. A convenience method for looking up an object with the given kwargs - creating one if necessary.
related_name
get_or_create(**kwargs)
reverse name
aggregate(args - *kwargs)

47. Returns an integer representing the number of objects in the database matching the QuerySet. This never raises exceptions.
Proxy model
count()
many-to-one relationship
in

48. If this option is True - Django will store empty values as NULL in the database. Default is False.
Abstract base class
null
many-to-many relationship
update(**kwargs)

49. 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.
create(**kwargs)
default
ForeignKey
in

50. This query updates all the headlines with pub_date in 2007 to read 'Everything is the same'.

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