添加外键到Django模型 [英] Adding Foreign Key To Django Model

问题描述

我想知道在将列从IntegerField转换为外键的最佳过程中。这是我的两个模型：

 类锻炼（models.Model）：
 
 userid = models。 IntegerField（）
 datesubmitted = models.DateField（）
 workoutdate = models.DateField（）; 
 bodyweight = models.FloatField（null = True）; 
 totalreps = models.IntegerField（）
 totalweight = models.FloatField（）
 numsets = models.IntegerField（）; 
 numexercises = models.IntegerField（）
 workoutname = models.CharField（max_length = 250）
  

和第二个：

 类运动（models.Model）：
 userid = models.IntegerField （）; 
 workoutid = models.IntegerField（）; 
 exercisename = models.CharField（max_length = 100）
 repetitions = models.IntegerField（）
 weight = models.FloatField（）
  

最后我的django视图代码：

  user = User。 object.get（username = request.session ['username']）#user 
 dates = request.GET.getlist（'datepickerfilter'）＃two dates 
 workout_ids = workout.objects.filter（userid = user.id）.filter（workoutdate__gte = dates [0]）。filter（workoutdate__lte = dates [1]）$ ​​b $ b all_exercises = exercise.objects.filter（workoutid__in = workout_ids）
  

我想将练习模型中的workoutid列更改为与锻炼模型中的id字段相关的外键。我试过这个改变模型领域：

  workoutid = models.ForeignKey（锻炼）; 
  

然后将这个order_by语句添加到我的视图中的all_exercises结尾，即

  all_exercises = exercise.objects.filter（workoutid__in = workout_ids）.order_by（workoutid__workoutdate）
  / pre> 
 
 
我收到一条错误，说：
 （1054 ，现场列表中的未知列tracking_exercise.workoutid_id）
  
我认为这是一个我的模型代码中的问题，但我不知道这可能是一个问题的视图。 
 
 
 
感谢您的帮助！ 
解决方案
您收到错误，因为workout_ids不是ids列表。
 
 
 
对于您当前的问题，快速简单的修复是使用 .values_list（'id'，flat = True）像这样：
  workout_ids = workout.objects.filter（userid = user.id）.\ 
 filter（workoutdate__gte = dates [0]）。 \\ 
过滤器（workoutdate__lte = dates [1]）。\ 
 values_list（'id'，flat = True）
  
但是，我强烈建议使用 models.ForeignKey 。这是一个简单的例子，让你开始：
  class Workout：
 user = models.ForeignKey（User）
＃其他字段去这里... 
 
类练习：
 workout = models.ForeignKey（锻炼）
＃其他字段去这里... 
  
然后你可以编写查询：
 code> workout_list = Workout.objects.filter（user = request.user）
 exercise_list = Exercise.objects.filter（workout__in = workout_list）.order_by（'workout__workoutdate'）
  
 
I was wondering what they best procedures in turning a column from an IntegerField to a Foreign Key. Here are my two models: 
class workout(models.Model):

    userid = models.IntegerField()
    datesubmitted = models.DateField()
    workoutdate = models.DateField(); 
    bodyweight = models.FloatField(null=True);
    totalreps = models.IntegerField() 
    totalweight = models.FloatField()
    numsets = models.IntegerField(); 
    numexercises = models.IntegerField()
    workoutname = models.CharField(max_length=250)
and the second one: 
class exercise(models.Model):  
    userid = models.IntegerField();
    workoutid = models.IntegerField(); 
    exercisename = models.CharField(max_length = 100)
    repetitions = models.IntegerField()
    weight = models.FloatField()
and finally my django view code: 
user =User.objects.get(username = request.session['username']) #user 
        dates = request.GET.getlist('datepickerfilter') # two dates
        workout_ids = workout.objects.filter(userid=user.id).filter( workoutdate__gte = dates[0]).filter(workoutdate__lte = dates[1])
        all_exercises = exercise.objects.filter(workoutid__in = workout_ids)
I want to change the 'workoutid' column in the exercise model to a foreign key that relates to the id field in the workout model. I tried this changing the changing the model field to: 
workoutid = models.ForeignKey(workout);
and then add this this order_by statement to the end of all_exercises in my view i.e 
all_exercises = exercise.objects.filter(workoutid__in = workout_ids).order_by("workoutid__workoutdate")
i get an error saying that:
(1054, "Unknown column 'tracking_exercise.workoutid_id' in 'field list'")
I think it is a problem in my Model code, but i'm not sure possibly it is an issue with the view. 

Thanks for the help guys! 
解决方案
You are getting the error because workout_ids isn't a list of ids.

A quick and simple fix to your current problem is to use .values_list('id', flat=True) like so:
workout_ids = workout.objects.filter(userid=user.id).\
    filter(workoutdate__gte=dates[0]).\
    filter(workoutdate__lte=dates[1]).\
    values_list('id', flat=True)
However, I would highly recommend using models.ForeignKey. Here's a simple example to get you started:
class Workout:
    user = models.ForeignKey(User)
    # other fields go here...

class Exercise:
    workout = models.ForeignKey(Workout)
    # other fields go here...
Then you can write the query:
workout_list = Workout.objects.filter(user=request.user)
exercise_list = Exercise.objects.filter(workout__in=workout_list).order_by('workout__workoutdate')


                        
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