You already learn how to filter query set in the previous video. This video will demonstrate something else important called ordering or sorting. You learn how to sort the APA result in ascending or descending order based on query string. There is a DRF package called django-filters, which offers advanced filtering, sorting, and searching. But that package is mostly used with class-based views. Since you are using function based views with API view decorator, you can take advantage of django's native sorting methods. After the implementation is done, menu items can be sorted using this query string with the menu items endpoint, http://127.0.0.1:8000/ api/menu-items? ordering equals price or http://127.0.0.1:8000/api/menu-items?ordering equals price,inventory. Let's open the menu items function. You need to exit a new query string parameter called ordering at this line, just after the search. Ordering equals request dot query underscore params, dot get, open bracket, single quotation mark ordering, single quotation mark, closed bracket. Now, just before the line where you created the serialized items, add these lines. With this line, you are sorting the query set by the value supplied with the ordering query string. Now, visit the menu items endpoint with ordering set to price. What do you notice? The menu items are now properly sorted by price in an ascending fashion, which means the items with lowest prices go at the top. How can you change the sorting order from ascending to descending so that the item with the highest price goes at the top. Do you need to make any changes to the code? Surprisingly, no code change is required just visit the menu items with ordering set to minus sign price, and you'll notice the expected result in a browsable APA view. Now, you learn how to implement sorting or ordering for your APA result with just a few lines of code. But there is still room for improvements. What if the client wants to sort the result by two fields, price and inventory just like this. You use your normal endpoint but at the end it reads menu items question mark, ordering equals price comma inventory. This way, items will be sorted by price first and then buy inventory in ascending fashion. This means that if two menu items have the same price but different inventory values, the one with the lower value will go at the top. How can you do this? You need to split the ordering field with a comma and call the order by ID method with that list, you don't need any for-loop for this. Remove this line, you add it before the serialized items and split the value of the ordering query string by a comma with this line. Ordering underscore fields equals ordering dot split, open bracket, double quotation mark, coma, double quotation mark, close bracket. Now you can call order by on the items query set for all those fields in the ordering field array with this line passing the list as arguments. That's it you are done. Let's visit the menu items endpoint with a query string like this ordering equals price comma inventory. The result is sorted exactly as it should be. What if you want to sort by price in ascending order and then by inventory in descending order. Simply pass this query string to the menu items endpoint ordering equals price, minus sign inventory. Notice specifically the minus sign before inventory and the result changes as expected. Now you'll learn how to sort the result of your API by multiple fields in both ascending and descending order. In this video, you'll learn how to sort the query set using djando built-in order by method in ascending and descending order. You will also learn how to accept multiple fields in the query string and sort according to them and finally, you'll learn about the django-filters class, which is powerful, but mainly works with class based views.
