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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. 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
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update(**kwargs)
add()
update()

2. 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.
all()
isnull
Restrictions on field names
many-to-one relationship

3. 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.
add()
regex
iexact
Multi-table inheritance

4. Lookup type that returns results with a case-insensitive start sequence.
none()
isnull
istartswith
db

5. Lookup type for date/datetime fields that finds an exact month match. Takes an integer 1 (January) through 12
month
null
one-to-one relationship
related_name

6. Exception raised by get(**kwargs) if more than one item matches the query.
MultipleObjectsReturned
slicing
exclude(**kwargs)
reverse()

7. 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

8. 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.
reverse()
~
gt
Manager

9. These are specified as keyword arguments to the QuerySet methods filter() - exclude() and get(). These take the form field__lookuptype=value .
filter(**kwargs)
Field lookups
many-to-one relationship
lte

10. 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.
~
exact
__unicode__()
primary_key

11. Defines a many-to-many relationship. You use it just like any other Field type: by including it as a class attribute of your model.
help_text
order_by(*fields)
ManyToManyField
reverse name

12. 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.
Multi-table inheritance
regex
lt
values_list(*fields)

13. Lookup type for date/datetime fields that finds an exact year match. Takes a four-digit year.
class attributes
gt
exclude(**kwargs)
year

14. Defined by a ManyToManyField. You use it just like any other Field type: by including it as a class attribute of your model.
in_bulk(id_list)
iendswith
primary_key
many-to-many relationship

15. 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.
Entry.objects.filter(id__in=[1 - 3 - 4])
range
dates(field - kind - order='ASC')
using(alias)

16. A manager method that returns a new QuerySet containing objects that do not match the given lookup parameters.
Restrictions on field names
pk
delete()
exclude(**kwargs)

17. 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
many-to-one relationship
Many-to-many relationship through an intermediate model
Entry.objects.filter(id__in=[1 - 3 - 4])
through argument

18. A convenience method for looking up an object with the given kwargs - creating one if necessary.
DoesNotExist
get_or_create(**kwargs)
only(*fields)
&

19. Each one of these is a Python class that subclasses django.db.models.Model. Each attribute of one of these represents a database field.
lt
add()
Meta class
model

20. To activate your models
get(**kwargs)
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
default
~

21. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.
ordered
Many-to-many relationship to self
class attributes
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)

22. 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.
Meta class
get_absolute_url()
default
clear() method

23. The default for this is the name of the child class followed by '_set'.
__unicode__()
reverse name
many-to-many relationship
iexact

24. This query finds all entries between a start date of start_date and an end date of end_date.
help_text
Entry.objects.filter(pub_date__range=(start_date - end_date))
iterator()
Model metadata

25. Lookup type that returns results greater than a given value.
range
gt
values(*fields)
update()

26. 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.
iregex
pk
in_bulk(id_list)
iendswith

27. This model method saves a model instance to the database. This method has no return value.
save()
db
F()
iterator()

28. This represents a collection of objects from your database. It can have zero - one or many filters.
reverse()
QuerySet
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
help_text

29. Lookup type that yields a case-insensitive match.
in_bulk(id_list)
iexact
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
contains

30. 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
distinct()
ManyToManyField
annotate(args - *kwargs)
Abstract base class

31. 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()
filter chaining
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
evaluation
Model metadata

32. Lookup type that finds a case-insensitive regular expression match.
F()
Manager methods
iregex
many-to-many relationship

33. Manager method used to retrieve every object in a model.
ordered
none()
filter(**kwargs)
all()

34. The database that will be used if this query is executed now
update(**kwargs)
delete()
db
in_bulk(id_list)

35. a QuerySet can be sliced - using Python's array-slicing syntax.
DoesNotExist
class type
slicing
ForeignKey

36. Disjunction operator for Q objects.
choices
get_absolute_url()
clear() method
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37. Used to get a QuerySet for a model. This is called 'objects' by default.
Manager
exists()
slicing
reverse()

38. If this option is True - Django will store empty values as NULL in the database. Default is False.
|
order_by(*fields)
DoesNotExist
null

39. This field is added automatically - but this behavior can be overridden
id field
class type
Model metadata
db

40. (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.
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
Multi-table inheritance
Entry.objects.filter(pub_date__year=2007).update(headline='Everything is the same')
Restrictions on field names

41. Operator for comparing two model instances for equality. Behind the scenes - it compares the primary key values of two models.
values_list(*fields)
startswith
F()
==

42. Negation operator for Q objects.
many-to-one relationship
delete()
~
==

43. Conjuntion operator for Q objects.
Q()
Model metadata
one-to-one relationship
&

44. Lookup type that returns results with a case-insensitive end sequence.
help_text
defer(*fields)
iendswith
reverse()

45. 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.
get_absolute_url()
&
update()
OneToOneField

46. Can be used to remove all many-to-many relationships for an instance
annotate(args - *kwargs)
iterator()
clear() method
using(alias)

47. 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()
startswith
isnull
endswith

48. 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(pub_date__year=2007).update(headline='Everything is the same')
only(*fields)
pickling
clear() method

49. This query deletes all Entry objects with a pub_date year of 2005.
Entry.objects.filter(pub_date__year=2005).delete()
annotate(args - *kwargs)
delete()
Meta class

50. 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.
one-to-one relationship
aggregate(args - *kwargs)
id field
gt