如何使用“Prefetch()”和“filter()”來減少“SELECT”查詢以迭代 3 個或更多模型?
[英]How to use "Prefetch()" with "filter()" to reduce `SELECT` queries to iterate 3 or more models?
我有Country , State和City模型,它們由外鍵鏈接,如下所示:class Country(models.Model): name = models.CharField(max_length=20) class State(models.Model): country ...