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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.
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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. 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.
reverse()
clear() method
Multi-table inheritance
many-to-one relationship

2. 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')
isnull
exclude(**kwargs)
&

3. 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_or_create(**kwargs)
get_absolute_url()
endswith
id field

4. 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
isnull
Entry.objects.filter(id__in=[1 - 3 - 4])
relationship spanning
startswith

5. Lookup type for date/datetime fields that finds an exact month match. Takes an integer 1 (January) through 12
month
get(**kwargs)
related_name
MultipleObjectsReturned

6. 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
values(*fields)
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
annotate(args - *kwargs)
endswith

7. A convenience method for constructing an object and saving it all in one step.
all()
evaluation
create(**kwargs)
==

8. 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.filter(id__in=[1 - 3 - 4])
Field lookups
isnull
Proxy model

9. 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.
only(*fields)
primary_key
delete()
reverse name

10. If you are using this attribute on a ForeignKey or ManyToManyField - you must always specify a unique reverse name for the field.
get_absolute_url()
when you add new apps to INSTALLED_APPS
related_name
Manager methods

11. 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
aggregate(args - *kwargs)
update(**kwargs)
Custom model methods
startswith

12. These are specified as keyword arguments to the QuerySet methods filter() - exclude() and get(). These take the form field__lookuptype=value .
Field lookups
search
exact
startswith

13. Lookup type that yields a case-insensitive match.
isnull
Field lookups
iexact
add()

14. To activate your models
update(**kwargs)
get_absolute_url()
OneToOneField
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.

15. 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
Model metadata
F()
MultipleObjectsReturned
get_absolute_url()

16. This sets a field to a particular value for all the objects in a QuerySet. You can only set non-relation fields and ForeignKey fields using this method.
lte
reverse()
__unicode__()
update()

17. This query uses an F object to increment the pingback count for every entry in the blog.

18. A convenience method for looking up an object with the given kwargs - creating one if necessary.
get_or_create(**kwargs)
istartswith
Restrictions on field names
OneToOneField

19. If this option is True - the field is allowed to be blank. Default is False.
iregex
blank
range
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)

20. Operator for comparing two model instances for equality. Behind the scenes - it compares the primary key values of two models.
==
Manager methods
id field
get(**kwargs)

21. Lookup type for date/datetime fields that finds a 'day of the week' match.
primary_key
Q()
ForeignKey
week_day

22. 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.
DoesNotExist
update()
aggregate(args - *kwargs)
order_by(*fields)

23. A QuerySet is iterable - and it executes its database query the first time you iterate over it.
iteration
class attributes
Manager methods
all()

24. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.
week_day
slicing
ordered
pickling

25. A Python "magic method" that returns a unicode "representation" of any object.
aggregate(args - *kwargs)
iendswith
__unicode__()
exists()

26. 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.
range
delete()
get(**kwargs)
null

27. A Manager method that returns a new QuerySet containing objects that match the given lookup parameters.
values(*fields)
endswith
filter(**kwargs)
in

28. Exception raised by get(**kwargs) if more than one item matches the query.
many-to-many relationship
null
MultipleObjectsReturned
__unicode__()

29. Lookup type that returns results in a given list.
relationship spanning
iexact
update()
in

30. Manager method used to retrieve every object in a model.
all()
defer(*fields)
aggregate(args - *kwargs)
reverse()

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
regex
none()
null
Q(question__istartswith='What')

32. 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()
id field
count()
iteration

33. 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
DoesNotExist
filter(**kwargs)
MultipleObjectsReturned
intermediate models

34. 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.
search
Entry.objects.filter(pub_date__range=(start_date - end_date))
week_day
filter chaining

35. This field is added automatically - but this behavior can be overridden
id field
when you add new apps to INSTALLED_APPS
istartswith
many-to-many relationship

36. 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.
choices tuple
latest(field_name=None)
Field lookups
year

37. Lookup type that returns results with a case-insensitive start sequence.
istartswith
reverse name
default
Entry.objects.filter(pub_date__range=(start_date - end_date))

38. Lookup type that returns results with a case-sensitive end sequence.
ordered
endswith
week_day
model

39. Can be used to remove all many-to-many relationships for an instance
clear() method
Entry.objects.filter(pub_date__range=(start_date - end_date))
regex
aggregate(args - *kwargs)

40. The default for this is the name of the child class followed by '_set'.
related_name
ordered
reverse name
get_absolute_url()

41. A Q object that encapsulates queries for entries with a question value that starts with 'What' in a case-insensitive fashion.

42. This query finds all entries with an id in the list [1 - 3 - 4]
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
istartswith
dates(field - kind - order='ASC')
Entry.objects.filter(id__in=[1 - 3 - 4])

43. Disjunction operator for Q objects.
Field lookups
choices
|
primary_key

44. 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.
ordered
choices
none()
update()

45. Lookup type that returns results less than or equal to a given value.
relationship spanning
lte
none()
related_name

46. Returns a new QuerySet containing objects that match the given lookup parameters.
Multi-table inheritance
filter(**kwargs)
all()
using(alias)

47. This model method saves a model instance to the database. This method has no return value.
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
~
save()
endswith

48. Returns the object matching the given lookup parameters
get(**kwargs)
__unicode__()
order_by(*fields)
~

49. This is a criterion that narrow down a QuerySet based on given parameters.
save()
filter
regex
class type

50. A manager method that returns a new QuerySet containing objects that do not match the given lookup parameters.
choices tuple
exclude(**kwargs)
__unicode__()
Many-to-many relationship through an intermediate model