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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. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.
reverse()
iteration
__unicode__()
distinct()

2. Returns the most recent object in the table - by date - using the field_name provided as the date field.
latest(field_name=None)
|
reverse()
id field

3. Lookup type that finds a case-sensitive regular expression match.
DoesNotExist
many-to-one relationship
regex
class attributes

4. (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.
all()
Restrictions on field names
get(**kwargs)
filter

5. 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.
save()
many-to-one relationship
Q()
latest(field_name=None)

6. Returns the object matching the given lookup parameters
values_list(*fields)
count()
update(**kwargs)
get(**kwargs)

7. 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
week_day
through argument
null

8. This model method saves a model instance to the database. This method has no return value.
many-to-one relationship
intermediate models
clear() method
save()

9. Fields are specified by these
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
get(**kwargs)
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
class attributes

10. Lookup type for date/datetime fields that finds an exact day match.
relationship spanning
Many-to-many relationship to self
Entry.objects.filter(id__in=[1 - 3 - 4])
day

11. Defined by a ManyToManyField. You use it just like any other Field type: by including it as a class attribute of your model.
Q(question__istartswith='What')
Entry.objects.filter(id__in=[1 - 3 - 4])
many-to-many relationship
week_day

12. Extra text to be displayed under the field on the object's admin form to provide assistance to users. It's useful for documentation even if your object doesn't have an admin form.
order_by(*fields)
Entry.objects.filter(id__gt=4)
help_text
Q(question__istartswith='What')

13. This is a criterion that narrow down a QuerySet based on given parameters.
delete()
filter
create(**kwargs)
class type

14. 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
pk
endswith
Many-to-many relationship through an intermediate model

15. Used to get a QuerySet for a model. This is called 'objects' by default.
Entry.objects.filter(id__in=[1 - 3 - 4])
filter(**kwargs)
Manager
delete()

16. These methods are intended to do "table-wide" things.
Manager methods
null
get(**kwargs)
save()

17. 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
get(**kwargs)
intermediate models
when you add new apps to INSTALLED_APPS
Q()

18. 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.
one-to-one relationship
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
annotate(args - *kwargs)
Multi-table inheritance

19. 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
defer(*fields)
slicing
one-to-one relationship
iterator()

20. If this option is True - the field is allowed to be blank. Default is False.
contains
Manager methods
unique
blank

21. The default for this is the name of the child class followed by '_set'.
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
endswith
reverse name

22. Keyword shortcut for looking up an object by primary key.
regex
save()
get(**kwargs)
pk

23. 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
Many-to-many relationship to self
unique
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.

24. Lookup type for date/datetime fields that finds an exact year match. Takes a four-digit year.
delete()
class type
year
get_or_create(**kwargs)

25. This query finds all entries with an id greater than 4.
gt
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
Entry.objects.filter(id__gt=4)
Model metadata

26. 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.
model
slicing
Field lookups
Many-to-many relationship through an intermediate model

27. 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.
get_absolute_url()
choices
filter chaining
dates(field - kind - order='ASC')

28. Manager method used to retrieve every object in a model.
all()
aggregate(args - *kwargs)
Custom model methods
exact

29. 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.
OneToOneField
Q()
values_list(*fields)
annotate(args - *kwargs)

30. 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

31. A QuerySet is iterable - and it executes its database query the first time you iterate over it.
istartswith
Meta class
iteration
Entry.objects.filter(id__gt=4)

32. Lookup type that returns results less than a given value.
range
get(**kwargs)
DoesNotExist
lt

33. A convenience method for looking up an object with the given kwargs - creating one if necessary.
get_or_create(**kwargs)
ManyToManyField
order_by(*fields)
Field lookups

34. This field is added automatically - but this behavior can be overridden
Abstract base class
save()
none()
id field

35. If you are using this attribute on a ForeignKey or ManyToManyField - you must always specify a unique reverse name for the field.
day
lte
related_name
values(*fields)

36. 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.
id field
iregex
F()
Q()

37. Can be used to remove all many-to-many relationships for an instance
choices
many-to-many relationship
clear() method
get(**kwargs)

38. This query finds all entries with an id in the list [1 - 3 - 4]
create(**kwargs)
add()
select_related()
Entry.objects.filter(id__in=[1 - 3 - 4])

39. Lookup type for date/datetime fields that finds a 'day of the week' match.
Entry.objects.filter(id__gt=4)
many-to-one relationship
week_day
reverse()

40. 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
null
save()
filter(**kwargs)
update(**kwargs)

41. Operator for comparing two model instances for equality. Behind the scenes - it compares the primary key values of two models.
choices
many-to-many relationship
==
filter(**kwargs)

42. Lookup type for date/datetime fields that finds an exact month match. Takes an integer 1 (January) through 12
F()
Q(question__istartswith='What')
month
exclude(**kwargs)

43. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.
ordered
many-to-one relationship
pickling
only(*fields)

44. These are specified as keyword arguments to the QuerySet methods filter() - exclude() and get(). These take the form field__lookuptype=value .
exists()
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
Field lookups
F()

45. Lookup type that returns results in a given list.
db
one-to-one relationship
id field
in

46. 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)
Restrictions on field names
filter(**kwargs)
model

47. These add custom "row-level" functionality to your objects. These act on a particular model instance.
Abstract base class
Meta class
Custom model methods
blank

48. 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
search
year
exists()
many-to-one relationship

49. Lookup type that takes either True or False and corresponds to SQL queries of IS NULL and IS NOT NULL - respectively.
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
contains
|
isnull

50. Lookup type that returns results with a case-insensitive start sequence.
reverse()
week_day
istartswith
get_absolute_url()