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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. 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.






2. 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.






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.






4. Lookup type for date/datetime fields that finds a 'day of the week' match.






5. These add custom "row-level" functionality to your objects. These act on a particular model instance.






6. 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






7. This model method is used for updating a ManyToManyField.






8. Lookup type that returns results greater than or equal to a given value.






9. 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






10. Returns a QuerySet that will automatically "follow" foreign-key relationships - selecting that additional related-object data when it executes its query. This is a performance booster which results in (sometimes much) larger queries but means later u






11. Keyword shortcut for looking up an object by primary key.






12. The default for this is the name of the child class followed by '_set'.






13. Manager method used to retrieve every object in a model.






14. Each one of these is a Python class that subclasses django.db.models.Model. Each attribute of one of these represents a database field.






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.






16. 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.






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

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183


18. Lookup type for date/datetime fields that finds an exact year match. Takes a four-digit year.






19. 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.






20. If this option is True - the field is allowed to be blank. Default is False.






21. 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.






22. A manager method which returns a single object. If there are no results that match the query - this method will raise a DoesNotExist exception. If more than one item matches this query - the method will raise MultipleObjectsReturned.






23. This query finds all entries between a start date of start_date and an end date of end_date.






24. Lookup type that returns results with a case-sensitive start sequence.






25. A convenience method for constructing an object and saving it all in one step.






26. Operator for comparing two model instances for equality. Behind the scenes - it compares the primary key values of two models.






27. This query deletes all Entry objects with a pub_date year of 2005.






28. Lookup type that tests for inclusion in a case-sensitive fashion.






29. 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






30. Returns the object matching the given lookup parameters






31. Returns a new QuerySet that uses SELECT DISTINCT in its SQL query. This eliminates duplicate rows from the query results.






32. A Manager method that returns a new QuerySet containing objects that match the given lookup parameters.






33. Returns an integer representing the number of objects in the database matching the QuerySet. This never raises exceptions.






34. a QuerySet can be sliced - using Python's array-slicing syntax.






35. 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






36. 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


37. 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






38. 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.






39. 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.






40. Exception raised by get(**kwargs) if no items match the query.






41. 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.






42. Lookup type that returns results less than or equal to a given value.






43. Lookup type that returns results with a case-insensitive start sequence.






44. (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.






45. Lookup type for date/datetime fields that finds an exact day match.






46. 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.






47. This method immediately deletes the object and has no return value.






48. A convenience method for looking up an object with the given kwargs - creating one if necessary.






49. Conjuntion operator for Q objects.






50. Used to get a QuerySet for a model. This is called 'objects' by default.