Using the prefetch_related() method

The prefetch_related() method is used as a performance booster on queries pertaining to ManyToManyField relationships. This method can also be used for ForeignKey and OneToOneField relationships and allows for forward and backward lookups, as we will soon practice doing. On the SQL level, this method will generally use a WHERE or INNER JOIN statement to perform lookup operations. Unlike the select_related() method, the prefetch_related() method will perform a separate SQL query for each of the related sets of objects. For example, if we looked up a Seller and wanted the related Vehicles and their related VehicleModel and Engine objects, then Django would perform four separate queries to look up all the related data. To learn more about the prefetch_related() method in its entirety, visit https://docs.djangoproject.com/en/4.0/ref/models/querysets/#prefetch-related.

The following are two exercises, related to the vehicles view and the sellers view...