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Django Queryset

Subject : it-skills

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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.
distinct()
choices tuple
Entry.objects.filter(pub_date__range=(start_date - end_date))
slicing

2. 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
get_absolute_url()
Q(question__startswith='Who') | ~Q(pub_date__year=2005)
update(**kwargs)
lte

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.
get(**kwargs)
id field
Q()

4. A Python "magic method" that returns a unicode "representation" of any object.
__unicode__()
dates(field - kind - order='ASC')
intermediate models
class attributes

5. 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.
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
OneToOneField
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
F()

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

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

8. These methods are intended to do "table-wide" things.
F()
Custom model methods
Manager methods
model

9. 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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10. Conjuntion operator for Q objects.
iendswith
all()
&
Custom model methods

11. 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
Manager methods
lt
defer(*fields)
create(**kwargs)

12. Lookup type that returns results with a case-sensitive start sequence.
only(*fields)
startswith
unique
range

13. Returns a ValuesQuerySet -- a QuerySet that returns dictionaries when used as an iterable - rather than model-instance objects.
all()
values(*fields)
id field
filter(**kwargs)

14. 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.
Multi-table inheritance
QuerySet
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
week_day

15. 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
exists()
many-to-many relationship
using(alias)
gte

16. Returns a new QuerySet containing objects that match the given lookup parameters.
Many-to-many relationship to self
pk
iterator()
filter(**kwargs)

17. Lookup type that takes either True or False and corresponds to SQL queries of IS NULL and IS NOT NULL - respectively.
isnull
Abstract base class
year
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.

18. The default for this is the name of the child class followed by '_set'.
reverse name
id field
all()
Restrictions on field names

19. 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
only(*fields)
filter
F()
get(**kwargs)

20. 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
get_or_create(**kwargs)
through argument
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
when you add new apps to INSTALLED_APPS

21. A QuerySet is iterable - and it executes its database query the first time you iterate over it.
get_or_create(**kwargs)
exclude(**kwargs)
ForeignKey
iteration

22. 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
isnull
intermediate models
exact
QuerySet

23. If this option is True - Django will store empty values as NULL in the database. Default is False.
db
primary_key
Proxy model
null

24. 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.
Entry.objects.filter(pub_date__range=(start_date - end_date))
exact
OneToOneField
Abstract base class

25. Lookup type that returns results in a given list.
MultipleObjectsReturned
in
when you add new apps to INSTALLED_APPS
QuerySet

26. 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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27. Lookup type that returns results greater than or equal to a given value.
Entry.objects.filter(pub_date__year=2005).delete()
choices
gte
all()

28. Defined by a ManyToManyField. You use it just like any other Field type: by including it as a class attribute of your model.
Entry.objects.filter(pub_date__year=2005).delete()
lte
many-to-many relationship
filter(**kwargs)

29. Returns the most recent object in the table - by date - using the field_name provided as the date field.
class type
get(**kwargs)
latest(field_name=None)
class attributes

30. 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
Model metadata
Field lookups
~

31. When to run syncdb
Model metadata
Many-to-many relationship through an intermediate model
default
when you add new apps to INSTALLED_APPS

32. 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.
class type
Entry.objects.filter(pub_date__range=(start_date - end_date))
exclude(**kwargs)
ForeignKey

33. A convenience method for constructing an object and saving it all in one step.
year
create(**kwargs)
lte
relationship spanning

34. 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
model
in_bulk(id_list)
Field lookups

35. Lookup type that returns results that fall into an inclusive date range.
~
OneToOneField
Entry.objects.filter(id__gt=4)
range

36. This model method is used for updating a ManyToManyField.
Manager methods
add()
choices tuple
|

37. Returns an integer representing the number of objects in the database matching the QuerySet. This never raises exceptions.
istartswith
contains
iteration
count()

38. This model method saves a model instance to the database. This method has no return value.
all()
class attributes
Many-to-many relationship through an intermediate model
save()

39. 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
istartswith
Entry.objects.filter(pub_date__range=(start_date - end_date))
intermediate models
only(*fields)

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

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41. 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.
Abstract base class
choices tuple
get_absolute_url()
update()

42. 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.
Field lookups
delete()
Multi-table inheritance
create(**kwargs)

43. 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
Restrictions on field names
search
choices tuple

44. 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.
annotate(args - *kwargs)
choices tuple
search
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.

45. Defined by a OneToOneField. You use it just like any other Field type: by including it as a class attribute of your model.
lt
day
one-to-one relationship
range

46. This method immediately deletes the object and has no return value.
get_absolute_url()
delete()
Many-to-many relationship to self
save()

47. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.
choices tuple
relationship spanning
ordered
Q()

48. 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.
help_text
search
Proxy model
choices

49. Lookup type that returns results less than or equal to a given value.
get_absolute_url()
through argument
lte
Many-to-many relationship to self

50. 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)
Manager methods
values(*fields)
Field lookups