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






2. 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






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






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






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






6. Lookup type for date/datetime fields that finds an exact year match. Takes a four-digit year.






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






8. The value given in the absence of a specified value for the field. This can be a value or a callable object. If callable it will be called every time a new object is created.






9. 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.






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






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






12. 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.






13. 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






14. 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.






15. 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.






16. (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.






17. If you are using this attribute on a ForeignKey or ManyToManyField - you must always specify a unique reverse name for the field.






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






19. 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






20. 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.






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






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






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






24. 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.






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






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






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






28. 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






29. 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.






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






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






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






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






34. Each one of these is a Python class that subclasses django.db.models.Model. Each attribute of one of these represents a database field.






35. 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)






36. 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.






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. 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






40. 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.






41. 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






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






43. 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()






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






45. 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.






46. 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.






47. This sets a field to a particular value for all the objects in a QuerySet. You can only set non-relation fields and ForeignKey fields using this method.






48. 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






49. To activate your models






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