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






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






3. The database that will be used if this query is executed now






4. Lookup type that yields a case-insensitive match.






5. 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.






6. 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.






7. 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






8. 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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9. This field is added automatically - but this behavior can be overridden






10. 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.






11. This represents a collection of objects from your database. It can have zero - one or many filters.






12. 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.






13. 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()






14. 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






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






16. 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.






17. 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.






18. 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.






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






20. 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






21. 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.






22. Lookup type for date/datetime fields that finds an exact month match. Takes an integer 1 (January) through 12






23. 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.






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






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






26. 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.






27. 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






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






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






30. Lookup type that returns results in a given list.






31. 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






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






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.






34. 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.






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






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






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






38. Lookup type that returns results with a case-sensitive end sequence.






39. Returns a new QuerySet containing objects that match the given lookup parameters.






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






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






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






43. 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.






44. This tells Django how to calculate the URL for an object. Django uses this in its admin interface - and any time it needs to figure out a URL for an object.






45. These methods are intended to do "table-wide" things.






46. If True - this field is the primary key for the model.






47. 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






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






49. Lookup type that finds a case-sensitive regular expression match.






50. Lookup type that returns results with a case-insensitive end sequence.