django--orm--01

 

Frequently Asked Questions dealing with a

Error message: myapp.Article.tags: (fields.W340) null has ManyToManyField ON NO Effect.

Solution: tags = models.ManyToManyField ( "Tag") with not null

FAQ treated titanium

报错信息：ERRORS:
myapp.Tag.date: (fields.E130) DecimalFields must define a 'decimal_places' attribute.
myapp.Tag.date: (fields.E132) DecimalFields must define a 'max_digits' attribute.

Solution: "decimal_places (there are several decimal places) and" DecimalFields field max_digits (total number of digits). "

 

class the Account (models.Model):
     "" " Account table " "" 
    username = models.CharField (= 64 MAX_LENGTH, UNIQUE = True) 
    password = models.CharField (MAX_LENGTH = 255 ) 
    In Email = models.EmailField (UNIQUE = True) 
    register_date = models.DateTimeField (auto_now_add = True) # Member auto_now_add the current time, it can not be overridden 
    signature = models.CharField ( " signature " , max_length = 255, null = True) 

class Article This article was (models.Model):
     "" " article table "" " 
    title = Models.CharField(max_length=255,unique=True)
    context = models.TextField()
    account = models.ForeignKey("Account",on_delete=models.CASCADE) #  models.CASCADE 当用户删除时，文章也删除
    tags = models.ManyToManyField("Tag")
    pub_date = models.DateTimeField()

class  Tag(models.Model):
    "标签表"
    name = models.CharField(max_length=64,unique=True)
    date = models.DateTimeField(auto_now_add=True)