在Django中進行多對多過濾

Question

我無法獲得此查詢以返回多個練習對象，即使我在sql中使用生成的查詢，它也按預期返回了兩個練習

class Workout(models.Model):
    created = models.DateTimeField(auto_now_add=True)
    workout_type = models.ForeignKey(WorkoutType, on_delete=models.CASCADE)
    exercises = models.ManyToManyField(Exercise, through=u'WorkoutExercise', related_name=u'workout_exercises')


class WorkoutExercise(models.Model):
    exercise = models.ForeignKey(Exercise)
    workout = models.ForeignKey(Workout)

class Exercise(models.Model):
    name = models.CharField(max_length=255, unique=True)

查詢是返回每次鍛煉以進行最新鍛煉

workouts = Workout.objects.latest('created')
    exercises = Exercise.objects.filter(workout_exercises__exact=workouts)

如前所述，這僅在它生成的查詢應且在sql中返回2時才返回單個練習。

Answer 1

它應該在沒有__exact情況下__exact ：

exercises = Exercise.objects.filter(workout_exercises=workouts)

但是，為什么不直接使用exercises字段：

workout = Workout.objects.latest('created')  # singular sounds more correct to me
exercises = workout.exercises.all()

順便說一句，這個相關名稱令人困惑。 我建議進行workouts或類似方法，因為您是通過exercise.workout_exercises而不是WorkoutExercise實例來管理Workout實例的。