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Django Queryset

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. 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.






2. 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.






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






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






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






6. 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.






7. 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.






8. 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.






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






10. If True - the table does not permit duplicate values for this field.






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

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12. 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.






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






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






15. 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.






16. 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






17. Conjuntion operator for Q objects.






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






19. 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






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






21. 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.






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






23. Adds to each object in the QuerySet with the provided list of aggregate values (averages - sums - etc) that have been computed over the objects that are related to the objects in the QuerySet. Each argument to this is content that will be added to ea






24. A QuerySet is iterable - and it executes its database query the first time you iterate over it.






25. This query finds all entries with an id greater than 4.






26. 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()






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






28. 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.






29. 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.






30. 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






31. Negation operator for Q objects.






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






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






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






35. 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.






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






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






38. 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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39. 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.






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






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






42. Returns the object matching the given lookup parameters






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






44. Lookup type that finds a case-insensitive regular expression match.






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






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






47. 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.






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






49. When to run syncdb






50. This style of inheritanc is useful when you're subclassing an existing model (perhaps something from another application entirely) and want each model to have its own database table. Here - each model in the hierarchy is a model all by itself.