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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. 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.






2. 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.






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






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






5. Conjuntion operator for Q objects.






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






7. 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.






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






9. When to run syncdb






10. 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.






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






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






13. 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.






14. Returns True if the QuerySet contains any results - and False if not. This tries to perform the query in the simplest and fastest way possible - but it does execute nearly the same query. This means that calling this method on a queryset is faster th






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






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






17. 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.






18. 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






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






20. 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.






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






22. restrictions on ________: (1) Your intermediate model must contain one - and only one - foreign key to the target model. (2) Your intermediate model must contain one - and only one - foreign key to the source model. (3) When defining a many-to-many r






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






24. 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






25. 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






26. 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






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






28. 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.






29. 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






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






31. 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.






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






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






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






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






37. 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.






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






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






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






41. 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






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






43. 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.






44. 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.






45. 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.






46. 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






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






48. 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.






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






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