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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 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.
evaluation
filter(**kwargs)
Entry.objects.filter(id__gt=4)
using(alias)

2. These add custom "row-level" functionality to your objects. These act on a particular model instance.
day
lt
Custom model methods
dates(field - kind - order='ASC')

3. This model method is used for updating a ManyToManyField.
blank
ordered
add()
filter

4. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.
filter(**kwargs)
Many-to-many relationship through an intermediate model
ForeignKey
ordered

5. 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)
class type
Model metadata
ordered
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)

6. 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.
Entry.objects.filter(pub_date__range=(start_date - end_date))
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
delete()
choices tuple

7. This represents a collection of objects from your database. It can have zero - one or many filters.
iregex
many-to-many relationship
month
QuerySet

8. Defined by a ManyToManyField. You use it just like any other Field type: by including it as a class attribute of your model.
dates(field - kind - order='ASC')
select_related()
MultipleObjectsReturned
many-to-many relationship

9. Lookup type that finds a case-sensitive regular expression match.
week_day
get(**kwargs)
gte
regex

10. 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__gt=4)
week_day
when you add new apps to INSTALLED_APPS
Proxy model

11. This gives your model metadata.
Meta class
update(**kwargs)
year
endswith

12. This query finds all entries with an id in the list [1 - 3 - 4]
Q()
relationship spanning
reverse name
Entry.objects.filter(id__in=[1 - 3 - 4])

13. This method immediately deletes the object and has no return value.
month
delete()
iregex
order_by(*fields)

14. Keyword shortcut for looking up an object by primary key.
aggregate(args - *kwargs)
pk
get_absolute_url()
in_bulk(id_list)

15. Lookup type for date/datetime fields that finds a 'day of the week' match.
Meta class
filter chaining
week_day
Entry.objects.filter(id__gt=4)

16. Lookup type for date/datetime fields that finds an exact month match. Takes an integer 1 (January) through 12
update()
search
gt
month

17. Lookup type that takes either True or False and corresponds to SQL queries of IS NULL and IS NOT NULL - respectively.
aggregate(args - *kwargs)
isnull
iregex
week_day

18. 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

19. Lookup type that returns results with a case-insensitive end sequence.
class attributes
contains
iendswith
order_by(*fields)

20. 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.
Entry.objects.filter(id__in=[1 - 3 - 4])
pickling
when you add new apps to INSTALLED_APPS
month

21. Lookup type that returns results with a case-sensitive start sequence.
get(**kwargs)
startswith
dates(field - kind - order='ASC')
Many-to-many relationship to self

22. 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.
class type
evaluation
help_text
intermediate models

23. The default for this is the name of the child class followed by '_set'.
defer(*fields)
Proxy model
reverse name
contains

24. Returns a ValuesQuerySet -- a QuerySet that returns dictionaries when used as an iterable - rather than model-instance objects.
count()
Many-to-many relationship to self
values(*fields)
many-to-one relationship

25. A Python "magic method" that returns a unicode "representation" of any object.
__unicode__()
QuerySet
delete()
through argument

26. 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

27. Lookup type that returns results with a case-insensitive start sequence.
defer(*fields)
filter(**kwargs)
istartswith
order_by(*fields)

28. Can be used to remove all many-to-many relationships for an instance
model
reverse()
filter chaining
clear() method

29. 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.
Entry.objects.filter(pub_date__year=2005).delete()
search
QuerySet
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)

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

31. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.
update(**kwargs)
distinct()
Many-to-many relationship through an intermediate model
db

32. This is a criterion that narrow down a QuerySet based on given parameters.
filter(**kwargs)
filter
Many-to-many relationship through an intermediate model
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.

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.
Entry.objects.filter(id__in=[1 - 3 - 4])
choices
values_list(*fields)
all()

34. The database that will be used if this query is executed now
distinct()
db
get(**kwargs)
lte

35. 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.
Restrictions on field names
annotate(args - *kwargs)
filter chaining
none()

36. 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.
count()
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
Entry.objects.filter(id__gt=4)
clear() method

37. This model method saves a model instance to the database. This method has no return value.
save()
contains
many-to-one relationship
lt

38. 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.
none()
delete()
intermediate models
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')

39. These are specified as keyword arguments to the QuerySet methods filter() - exclude() and get(). These take the form field__lookuptype=value .
Field lookups
week_day
range
intermediate models

40. 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.
order_by(*fields)
exact
ordered
default

41. Defined by a OneToOneField. You use it just like any other Field type: by including it as a class attribute of your model.
one-to-one relationship
values_list(*fields)
Model metadata
Entry.objects.filter(pub_date__year=2005).delete()

42. 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.
get_absolute_url()
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
search
aggregate(args - *kwargs)

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

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183

44. Used to get a QuerySet for a model. This is called 'objects' by default.
blank
order_by(*fields)
Manager
iexact

45. 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()
exists()
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
filter(**kwargs)

46. 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
create(**kwargs)
choices tuple
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
iterator()

47. 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.
search
gte
~
Many-to-many relationship to self

48. A convenience method for looking up an object with the given kwargs - creating one if necessary.
get_or_create(**kwargs)
Q(question__istartswith='What')
choices
Many-to-many relationship to self

49. A convenience method for constructing an object and saving it all in one step.
create(**kwargs)
&
clear() method
primary_key

50. 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
using(alias)
Q(question__istartswith='What')
many-to-one relationship
none()