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Test your basic knowledge |
Django Queryset
Start Test
Study First
Subject
:
it-skills
Instructions:
Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can
study here
.
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. Returns a copy of the current QuerySet (or QuerySet subclass you pass in). This can be useful in some situations where you might want to pass in either a model manager or a QuerySet and do further filtering on the result. You can safely call all() on
dates(field - kind - order='ASC')
Entry.objects.filter(pub_date__range=(start_date - end_date))
all()
lt
2. If True - the table does not permit duplicate values for this field.
unique
default
dates(field - kind - order='ASC')
search
3. 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.
clear() method
defer(*fields)
filter chaining
db
4. 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.
using(alias)
Model metadata
aggregate(args - *kwargs)
reverse()
5. This method immediately deletes the object and has no return value.
month
QuerySet
count()
delete()
6. Can be used to remove all many-to-many relationships for an instance
clear() method
intermediate models
distinct()
MultipleObjectsReturned
7. 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()
aggregate(args - *kwargs)
MultipleObjectsReturned
choices tuple
8. Lookup type that takes either True or False and corresponds to SQL queries of IS NULL and IS NOT NULL - respectively.
iendswith
using(alias)
Model metadata
isnull
9. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.
pickling
delete()
ordered
one-to-one relationship
10. Keyword shortcut for looking up an object by primary key.
pk
null
slicing
Entry.objects.filter(pub_date__range=(start_date - end_date))
11. If this option is True - Django will store empty values as NULL in the database. Default is False.
|
regex
exists()
null
12. Here - you can't use add - create - or assignment (i.e. - beatles.members = [...]) to create relationships. You need to specify all the detail for the relationship required by the intermediate model.
Many-to-many relationship through an intermediate model
DoesNotExist
|
iexact
13. 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
Entry.objects.filter(id__gt=4)
none()
null
get_or_create(**kwargs)
14. Exception raised by get(**kwargs) if more than one item matches the query.
annotate(args - *kwargs)
relationship spanning
lt
MultipleObjectsReturned
15. 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.
unique
in_bulk(id_list)
istartswith
latest(field_name=None)
16. Used to get a QuerySet for a model. This is called 'objects' by default.
dates(field - kind - order='ASC')
slicing
Manager
delete()
17. 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)
iregex
primary_key
istartswith
18. A manager method that returns a new QuerySet containing objects that do not match the given lookup parameters.
OneToOneField
iexact
exclude(**kwargs)
Entry.objects.filter(id__in=[1 - 3 - 4])
19. 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
annotate(args - *kwargs)
blank
only(*fields)
filter
20. 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.
evaluation
Many-to-many relationship to self
OneToOneField
choices tuple
21. A convenience method for constructing an object and saving it all in one step.
dates(field - kind - order='ASC')
create(**kwargs)
F()
Proxy model
22. This model method saves a model instance to the database. This method has no return value.
save()
exists()
in_bulk(id_list)
add()
23. Lookup type that returns results greater than a given value.
one-to-one relationship
gt
Entry.objects.filter(pub_date__range=(start_date - end_date))
get(**kwargs)
24. Lookup type for date/datetime fields that finds an exact year match. Takes a four-digit year.
&
clear() method
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
year
25. If this option is True - the field is allowed to be blank. Default is False.
range
blank
regex
iterator()
26. Lookup type that tests for inclusion in a case-sensitive fashion.
edit your settings file and change the INSTALLED_APPS setting to add the name of the module that contains your models.py.
|
contains
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
27. A QuerySet is iterable - and it executes its database query the first time you iterate over it.
filter chaining
__unicode__()
iteration
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
28. 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.
class attributes
using(alias)
MultipleObjectsReturned
default
29. If you are using this attribute on a ForeignKey or ManyToManyField - you must always specify a unique reverse name for the field.
select_related()
|
annotate(args - *kwargs)
related_name
30. This represents a collection of objects from your database. It can have zero - one or many filters.
DoesNotExist
QuerySet
clear() method
values(*fields)
31. Lookup type for date/datetime fields that finds an exact day match.
iteration
reverse()
day
Q(question__istartswith='What')
32. 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)
relationship spanning
add()
Model metadata
|
33. (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.
Q(question__istartswith='What')
Restrictions on field names
unique
Many-to-many relationship through an intermediate model
34. Defined by a ManyToManyField. You use it just like any other Field type: by including it as a class attribute of your model.
count()
select_related()
many-to-many relationship
week_day
35. Each one of these is a Python class that subclasses django.db.models.Model. Each attribute of one of these represents a database field.
aggregate(args - *kwargs)
all()
model
slicing
36. 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(**kwargs)
get(**kwargs)
through argument
evaluation
37. Lookup type that returns results greater than or equal to a given value.
Custom model methods
gte
evaluation
many-to-many relationship
38. 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.
delete()
order_by(*fields)
Custom model methods
get(**kwargs)
39. 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
40. 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.
OneToOneField
when you add new apps to INSTALLED_APPS
search
Entry.objects.filter(pub_date__year=2005).delete()
41. This sets a field to a particular value for all the objects in a QuerySet. You can only set non-relation fields and ForeignKey fields using this method.
update()
Q(question__istartswith='What')
one-to-one relationship
Q()
42. 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)
iexact
relationship spanning
aggregate(args - *kwargs)
43. This is a criterion that narrow down a QuerySet based on given parameters.
id field
filter
Entry.objects.filter(id__in=[1 - 3 - 4])
Entry.objects.all().update(n_pingbacks=F('n_pingbacks') + 1)
44. This query finds all entries with an id greater than 4.
Manager
all()
month
Entry.objects.filter(id__gt=4)
45. 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
through argument
only(*fields)
aggregate(args - *kwargs)
get_absolute_url()
46. 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.
model
many-to-many relationship
using(alias)
gte
47. The database that will be used if this query is executed now
extra(select=None - where=None - params=None - tables=None - order_by=None - select_params=None)
when you add new apps to INSTALLED_APPS
db
lte
48. 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
primary_key
Proxy model
filter(**kwargs)
update()
49. Lookup type that yields a case-insensitive match.
iexact
one-to-one relationship
choices tuple
choices
50. Manager method used to retrieve every object in a model.
values(*fields)
__unicode__()
delete()
all()