python - Django encountered problems operating the database and could not query the updated data

Question

I changed the properties of question_text and saved

Then add the __str__() method and query all Questions again,

My above code is implemented according to this
http://www.yiibai.com/django/... I just learned it. My steps are the same as this tutorial, which is to add __str__ () method, the correct display of the tutorial is as follows:

But I tested it myself and entered the command, but I couldn't see the records after I changed it. For example, I changed
q.question_text = "What's up?"
q.save()

After saving the changes, run the following command
Question.objects.all()
The result is as shown below:

What is the reason for this? —Django1.9, the database is the default sqlite3

Answer 1

def __str__ This should be the class method of the model Question. This method determines the return when you query. You define return self.question_text, so when you query the object, it will return the question_text attribute of the object, but your writing The format is wrong. If this method is defined outside the class, it becomes a single function and has nothing to do with the class. When you query, a Question object will be returned by default.

Answer 2

Thanks to tianren124 for the answer, the problem has been solved.
First you need to modify models.py:
models.py

# Create your models here.
class Question(models.Model):

    def __str__(self):
        return self.question_text
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')
    
class Chioce(models.Model):
    def __str__(self):
        return self.choice_text
    question = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)
    # 每个模型是django.db.models.Model类的子类
   
#def was_published_recently(self):
        #return self.pub_date >= timezone.now() - datetime.timedelta(days=1)

After changing the model.py code above, save it, open cmd, and re-enter it

C:\Users\Administrator\AppData\Local\Programs\Python\Python35\myproject>python m
anage.py runserver

Enter simultaneously

    C:\Users\Administrator\AppData\Local\Programs\Python\Python35\myproject>python m
anage.py shell
Python 3.5.2 (v3.5.2:4def2a2901a5, Jun 25 2016, 22:18:55) [MSC v.1900 64 bit (AM
D64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> import django
>>> django.setup()
>>> from polls.models import Question, Chioce
>>> Question.objects.all()
[<Question: What's up?>, <Question: What's up?>, <Question: What's up?>]
>>>

You can see that, unlike the results in the previous question, when Question.objects.all() is entered, the running result is the value after I change q.question_tex "What's up?
Solution:
1. Modify models.py

def __str__(self):
        return self.question_text
    

should be placed in

    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')

 def __str__(self):
        return self.choice_text

Also put

question = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

In front of me, I don’t quite understand why.
2. Pay attention to the indentation:

The expression may not be very clear, please correct me