With Extra Day Grace Period, you have an extra business day to make deposits and avoid overdraft fees. If your available balance covers the prior business day's overdraft items as of midnight Eastern Time, we'll waive the associated overdraft fees.
This is an old API that we aim to deprecate at some point in the future.Use it only if you cannot express your query using other queryset methods.If you do need to use it, please file a ticket using the QuerySet.extrakeywordwith your use case (please check the list of existing tickets first) sothat we can enhance the QuerySet API to allow removing extra(). We areno longer improving or fixing bugs for this method.
If you need to order the resulting queryset using some of the newfields or tables you have included via extra() use the order_byparameter to extra() and pass in a sequence of strings. Thesestrings should either be model fields (as in the normalorder_by() method on querysets), of the formtable_name.column_name or an alias for a column that you specifiedin the select parameter to extra().
Even if you think you are in the advanced use-case situation, only usedefer() when you cannot, at queryset load time, determine if you willneed the extra fields or not. If you are frequently loading and using aparticular subset of your data, the best choice you can make is tonormalize your models and put the non-loaded data into a separate model(and database table). If the columns must stay in the one table for somereason, create a model with Meta.managed = False (see themanaged attribute documentation)containing just the fields you normally need to load and use that where youmight otherwise call defer(). This makes your code more explicit to thereader, is slightly faster and consumes a little less memory in the Pythonprocess.
Additionally, if a some_queryset has not yet been evaluated, but you knowthat it will be at some point, then using some_queryset.exists() will domore overall work (one query for the existence check plus an extra one to laterretrieve the results) than using bool(some_queryset), which retrieves theresults and then checks if any were returned.
If you pass in a QuerySet resulting from values() or values_list()as the value to an __in lookup, you need to ensure you are only extractingone field in the result. For example, this will work (filtering on the blognames):
A library of extra functions for the standard Haskell libraries. Most functions are simple additions, filling out missing functionality. A few functions are available in later versions of GHC, but this package makes them available back to GHC 7.2.
The module Extra documents all functions provided by this library. Modules such as Data.List.Extra provide extra functions over Data.List and also reexport Data.List. Users are recommended to replace Data.List imports with Data.List.Extra if they need the extra functionality.