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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. Lookup type that returns results greater than or equal to a given value.
primary_key
when you add new apps to INSTALLED_APPS
year
gte

2. 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
update(**kwargs)
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
Entry.objects.filter(id__in=[1 - 3 - 4])
iterator()

3. Lookup type that returns results with a case-sensitive start sequence.
model
class type
ordered
startswith

4. 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
in
when you add new apps to INSTALLED_APPS
only(*fields)
Multi-table inheritance

5. 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.
blank
exact
reverse name
values_list(*fields)

6. Lookup type for date/datetime fields that finds an exact month match. Takes an integer 1 (January) through 12
month
Many-to-many relationship to self
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
range

7. 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.
ManyToManyField
lte
in
Restrictions on field names

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

9. 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
week_day
class attributes
intermediate models
&

10. When to run syncdb
lt
filter
when you add new apps to INSTALLED_APPS
ForeignKey

11. 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.
add()
update(**kwargs)
help_text
Model metadata

12. what the field _______ determines: (1) The database column type (e.g. INTEGER - VARCHAR); (2) The widget to use in Django's admin interface - if you care to use it (e.g. <input type="text"> - <select>); (3) The minimal validation requirements - used
pk
through argument
ForeignKey
class type

13. These are specified as keyword arguments to the QuerySet methods filter() - exclude() and get(). These take the form field__lookuptype=value .
intermediate models
filter
Multi-table inheritance
Field lookups

14. This query uses an F object to increment the pingback count for every entry in the blog.

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15. Returns a ValuesQuerySet -- a QuerySet that returns dictionaries when used as an iterable - rather than model-instance objects.
select_related()
count()
values(*fields)
Proxy model

16. Lookup type that returns results with a case-sensitive end sequence.
id field
get_or_create(**kwargs)
~
endswith

17. Returns the most recent object in the table - by date - using the field_name provided as the date field.
&
update(**kwargs)
latest(field_name=None)
contains

18. A QuerySet is iterable - and it executes its database query the first time you iterate over it.
iteration
Multi-table inheritance
help_text
iexact

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
ForeignKey
Many-to-many relationship through an intermediate model
F()
blank

20. 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.
get(**kwargs)
search
using(alias)
count()

21. Exception raised by get(**kwargs) if no items match the query.
contains
exact
help_text
DoesNotExist

22. Defined by a OneToOneField. You use it just like any other Field type: by including it as a class attribute of your model.
Multi-table inheritance
one-to-one relationship
Manager methods
Q(question__startswith='Who') | ~Q(pub_date__year=2005)

23. 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
aggregate(args - *kwargs)
values(*fields)
exists()
class attributes

24. This is a criterion that narrow down a QuerySet based on given parameters.
Abstract base class
gt
class type
filter

25. This query finds all entries with an id greater than 4.
distinct()
Entry.objects.filter(id__in=[1 - 3 - 4])
Entry.objects.filter(id__gt=4)
in_bulk(id_list)

26. This query deletes all Entry objects with a pub_date year of 2005.
Q()
pk
Entry.objects.filter(pub_date__year=2005).delete()
id field

27. Exception raised by get(**kwargs) if more than one item matches the query.
one-to-one relationship
exclude(**kwargs)
MultipleObjectsReturned
Entry.objects.filter(id__in=[1 - 3 - 4])

28. 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.
Entry.objects.filter(pub_date__year=2005).delete()
null
order_by(*fields)
exists()

29. Accomplish this by using the field name of related fields across models - separated by double underscores - until you get to the field you want. For example - to get all Entry objects with a Blog whose name is 'Beatles Blog': Entry.objects.filter(blo
values(*fields)
filter
relationship spanning
iendswith

30. 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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31. 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.
pickling
many-to-one relationship
using(alias)
filter

32. Lookup type that returns results in a given list.
lt
Multi-table inheritance
in
iregex

33. A Manager method that returns a new QuerySet containing objects that match the given lookup parameters.
filter(**kwargs)
filter chaining
update(**kwargs)
F()

34. A convenience method for constructing an object and saving it all in one step.
gt
Entry.objects.filter(pub_date__year=2005).delete()
create(**kwargs)
Manager

35. Lookup type that takes either True or False and corresponds to SQL queries of IS NULL and IS NOT NULL - respectively.
isnull
related_name
gt
contains

36. Fields are specified by these
OneToOneField
endswith
aggregate(args - *kwargs)
class attributes

37. Lookup type that returns results greater than a given value.
gt
select_related()
all()
day

38. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.
id field
==
values_list(*fields)
distinct()

39. A Python "magic method" that returns a unicode "representation" of any object.
DoesNotExist
gt
get(**kwargs)
__unicode__()

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
update(**kwargs)
contains
using(alias)
one-to-one relationship

41. 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
Manager methods
null
Model metadata
none()

42. 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
annotate(args - *kwargs)
choices
defer(*fields)
pickling

43. 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.
Manager
ForeignKey
in_bulk(id_list)
month

44. A convenience method for looking up an object with the given kwargs - creating one if necessary.
Meta class
get_or_create(**kwargs)
in_bulk(id_list)
pk

45. 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.
~
filter
pickling
Multi-table inheritance

46. Lookup type that tests for inclusion in a case-sensitive fashion.
week_day
exists()
contains
distinct()

47. If True - the table does not permit duplicate values for this field.
choices tuple
unique
range
day

48. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.
==
ordered
|
choices tuple

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

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50. 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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