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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.
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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. To activate your models






2. 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






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






4. Can be used to remove all many-to-many relationships for an instance






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






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






7. True if the QuerySet has an order_by() clause or a default ordering on the model. False otherwise.






8. 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.






9. 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.






10. 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.






11. 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






12. 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






13. Disjunction operator for Q objects.






14. 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






15. This query finds all entries with an id in the list [1 - 3 - 4]






16. If this option is True - Django will store empty values as NULL in the database. Default is False.






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






18. 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






19. Negation operator for Q objects.






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






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






22. 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






23. 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.






24. 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






25. 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.






26. Lookup type that takes either True or False and corresponds to SQL queries of IS NULL and IS NOT NULL - respectively.






27. This is a criterion that narrow down a QuerySet based on given parameters.






28. These are specified as keyword arguments to the QuerySet methods filter() - exclude() and get(). These take the form field__lookuptype=value .






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






30. 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






31. Lookup type that returns results that fall into an inclusive date range.






32. 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.






33. 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.






34. 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.






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






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






37. Defined by a OneToOneField. You use it just like any other Field type: by including it as a class attribute of your model.






38. Exception raised by get(**kwargs) if more than one item matches the query.






39. Returns the most recent object in the table - by date - using the field_name provided as the date field.






40. 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.






41. A manager method that returns a new QuerySet containing objects that do not match the given lookup parameters.






42. 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.






43. 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.






44. 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






45. Returns the object matching the given lookup parameters






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






47. When to run syncdb






48. This class type is useful when you just want to use the parent class to hold information that you don't want to have to type out for each child model. This class isn't going to ever be used in isolation. When it is used as a base class for other mode






49. If you are using this attribute on a ForeignKey or ManyToManyField - you must always specify a unique reverse name for the field.






50. Lookup type that returns results less than a given value.