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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. 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.






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






3. 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






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






5. 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.






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






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






8. This query uses an F object to increment the pingback count for every entry in the blog.

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






10. Fields are specified by these






11. This method returns tuples of values when iterated over. Each tuple contains the value from the respective field passed into the call to this method -- so the first item is the first field - etc.






12. 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






13. Returns the object matching the given lookup parameters






14. 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.






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






16. 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






17. 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.






18. 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






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






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






21. 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()






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






23. 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.






24. Disjunction operator for Q objects.






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






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






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






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






29. When to run syncdb






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






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






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






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






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






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






36. Negation operator for Q objects.






37. 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






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






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. 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.






42. 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






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






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






45. 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.






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






47. 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






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






49. To activate your models






50. 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.