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






2. 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






3. 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






4. Disjunction operator for Q objects.






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






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






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






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






9. 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.






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






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






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






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






14. 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.






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






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






17. 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






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






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






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






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






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






23. 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.






24. 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.






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






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






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






28. A Python "magic method" that returns a unicode "representation" of any object.






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






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






31. 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.






32. 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.






33. Conjuntion operator for Q objects.






34. 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






35. 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.






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






37. 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






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






39. Negation operator for Q objects.






40. 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)






41. 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.






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






43. 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






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






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






46. 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.






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






48. 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.






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






50. 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()