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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. Lookup type that returns results with a case-sensitive end sequence.
endswith
iendswith
default
iteration

2. 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.

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3. To activate your models
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
Manager
slicing

4. 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.
Q()
order_by(*fields)
iendswith
F()

5. 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
update(**kwargs)
&
db
reverse()

6. 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)
contains
using(alias)
range
Model metadata

7. Takes a list of primary-key values and returns a dictionary mapping each primary-key value to an instance of the object with the given ID.
in_bulk(id_list)
id field
F()
range

8. Lookup type for date/datetime fields that finds an exact day match.
day
gte
ForeignKey
select_related()

9. 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.
filter(**kwargs)
when you add new apps to INSTALLED_APPS
Q()
save()

10. The default for this is the name of the child class followed by '_set'.
reverse name
id field
save()
|

11. Returns an integer representing the number of objects in the database matching the QuerySet. This never raises exceptions.
iregex
count()
values(*fields)
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)

12. 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.
Many-to-many relationship to self
evaluation
using(alias)
choices tuple

13. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.
help_text
id field
distinct()
exact

14. 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.
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
primary_key
dates(field - kind - order='ASC')
filter chaining

15. Returns the most recent object in the table - by date - using the field_name provided as the date field.
Q(question__istartswith='What')
latest(field_name=None)
filter(**kwargs)
Meta class

16. This represents a collection of objects from your database. It can have zero - one or many filters.
Many-to-many relationship through an intermediate model
clear() method
QuerySet
Manager methods

17. Manager method used to retrieve every object in a model.
all()
delete()
Abstract base class
reverse name

18. If True - the table does not permit duplicate values for this field.
lt
Proxy model
unique
reverse name

19. This query finds all entries with an id in the list [1 - 3 - 4]
get(**kwargs)
none()
Entry.objects.filter(id__in=[1 - 3 - 4])
Entry.objects.filter(pub_date__range=(start_date - end_date))

20. Lookup type that returns results greater than a given value.
endswith
gt
Model metadata
in

21. 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
F()
filter(**kwargs)
filter
search

22. 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.
choices
filter chaining
Manager methods
aggregate(args - *kwargs)

23. This class type is useful when you just want to use the parent class to hold information that you don't want to have to type out for each child model. This class isn't going to ever be used in isolation. When it is used as a base class for other mode
Abstract base class
through argument
filter
filter chaining

24. Lookup type that tests for inclusion in a case-sensitive fashion.
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
contains
primary_key
F()

25. Fields are specified by these
class attributes
year
reverse()
save()

26. Lookup type that returns results with a case-insensitive end sequence.
ForeignKey
iendswith
year
intermediate models

27. Lookup type that finds a case-sensitive regular expression match.
using(alias)
filter
regex
iteration

28. 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.
Manager methods
Many-to-many relationship to self
~
Model metadata

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.
values_list(*fields)
filter chaining
when you add new apps to INSTALLED_APPS
latest(field_name=None)

30. If you are using this attribute on a ForeignKey or ManyToManyField - you must always specify a unique reverse name for the field.
related_name
Meta class
one-to-one relationship
many-to-one relationship

31. Each one of these is a Python class that subclasses django.db.models.Model. Each attribute of one of these represents a database field.
help_text
all()
Entry.objects.filter(pub_date__range=(start_date - end_date))
model

32. This gives your model metadata.
latest(field_name=None)
Entry.objects.filter(id__in=[1 - 3 - 4])
values(*fields)
Meta class

33. Defines a one-to-one relationship. You use it just like any other Field type: by including it as a class attribute of your model.
values(*fields)
model
OneToOneField
endswith

34. 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
model
iendswith
only(*fields)
Manager methods

35. 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
isnull
help_text
using(alias)

36. These are specified as keyword arguments to the QuerySet methods filter() - exclude() and get(). These take the form field__lookuptype=value .
Entry.objects.filter(pub_date__year=2005).delete()
clear() method
Field lookups
search

37. 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.
intermediate models
slicing
exists()
ForeignKey

38. 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.
help_text
Entry.objects.filter(pub_date__year=2005).delete()
primary_key
default

39. A Q object that asks for entries with a question value that start with 'Who' or do not have a publication date of 2005.

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40. If this option is True - the field is allowed to be blank. Default is False.
get(**kwargs)
in_bulk(id_list)
blank
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)

41. 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
startswith
model

42. A convenience method for constructing an object and saving it all in one step.
gt
through argument
create(**kwargs)
isnull

43. Returns a new QuerySet containing objects that match the given lookup parameters.
class attributes
filter(**kwargs)
Custom model methods
many-to-many relationship

44. 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
db
none()
blank
model

45. 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
exclude(**kwargs)
Proxy model
related_name
id field

46. 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.
QuerySet
id field
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
pk

47. This query finds all entries with an id greater than 4.
Entry.objects.filter(id__gt=4)
delete()
when you add new apps to INSTALLED_APPS
iregex

48. Lookup type that returns results greater than or equal to a given value.
gte
filter
Manager methods
range

49. (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.
isnull
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
class type
Restrictions on field names

50. This is a criterion that narrow down a QuerySet based on given parameters.
order_by(*fields)
in
none()
filter