Django和2個問題

Question

這是我的模型：

from django.db import models 
from depot.models import Subject, Student 

# Create your models here. 
class Credit(models.Model): 
    subject = models.ForeignKey(Subject) 
    number = models.IntegerField() 
    first_level_questions = models.IntegerField(default=8) 
    second_level_questions = models.IntegerField(default=8) 
    third_level_questions = models.IntegerField(default=4) 

class Question(models.Model): 
    credit = models.ForeignKey(Credit) 
    question = models.CharField(max_length=200) 
    level_choice = (
     (1, u'1'), 
     (2, u'2'), 
     (3, u'3'), 
    ) 
    level = models.IntegerField(choices=level_choice) 
    a = models.CharField(max_length=200, blank=True) 
    b = models.CharField(max_length=200, blank=True) 
    c = models.CharField(max_length=200, blank=True) 
    d = models.CharField(max_length=200, blank=True) 
    right_answer_choices = (
     (1, u'a'), 
     (2, u'b'), 
     (3, u'c'), 
     (4, u'd'), 
    ) 
    right_answer = models.IntegerField(choices=right_answer_choices, blank=True) 

class Answer(models.Model): 
    question = models.ForeignKey(Question) 
    student = models.ForeignKey(Student) 
    answer = models.CharField(max_length=400) 
    right = models.BooleanField(default=None) 

    def __unicode__(self): 
     return self.answer 

class Mark(models.Model): 
    student = models.ForeignKey(Student) 
    credit = models.ForeignKey(Credit) 
    total = models.IntegerField() 

這是我的admin.py：

from django.contrib import admin 
from credits.models import Credit, Question 

class QuestionInline(admin.StackedInline): 
    model = Question 
    extra = 0 

class CreditAdmin(admin.ModelAdmin): 
    list_display = ['subject', 'number'] 
    inlines = [QuestionInline,] 


admin.site.register(Credit, CreditAdmin) 

我解決我的第一個問題。謝謝。 我的第二個問題： 我想在我的標記模型中有一個方法。 你知道嗎：

def total_mark(self): 
    return Answer.objects.filter(student=self.student, right=True).count() 

但是信用呢？我需要準確的學生和確切的學分。

Answer 1

對於第一個問題，我認爲這與ChoiceField的值爲''（空字符串）如果沒有選擇任何東西有關。對於您正在創建的兩個選擇字段，這是一個問題，因爲它們需要整數，但不能將''轉換爲整數。我認爲當你提交表單時出現這個錯誤？您在提交時是否選擇了right_answer？我會嘗試從該字段中刪除blank=True - 畢竟，每個問題都應該有正確的答案！

---

關於你的第二個問題，你可能要像這樣在您的看法：

# given a student object s 
correct_answers = Answer.objects.filter(student=s, right=True).count() 
# now you can save the mark how you want