django's ORM three ways to create table-many ways

Three ways to create many-ways

1. Automatic (recommended *)

　　Advantage: You do not need to manually create the third table

　　Inadequate: As the third table than you created manually, which means the third table is fixed and can not do field expansion

class Book(models.Model):
    title = models.CharField(max_length=32)
    price = models.DecimalField(max_digits=8,decimal_places=2)
    authors = models.ManyToManyField(to='Author')

class Author(models.Model):
    name = models.CharField(max_length=32)

2. Pure manual (to understand)

Create their own third table

Advantages: can any third extension field

Inadequate: orm query is not convenient

class Book(models.Model):
    title = models.CharField(max_length=32)
    price = models.DecimalField(max_digits=8,decimal_places=2)


class Author(models.Model):
    name = models.CharField(max_length=32)
                
                
class Book2Author(models.Model):
    book = models.ForeignKey(to='Book')
    author = models.ForeignKey(to='Author')
    create_time = models.DateField(auto_now_add=True)

3. Semi-Automatic (recommended *******)

Advantages: automatic and combines the advantages of two pure manual

class Book (models.Model): 
   title = models.CharField (MAX_LENGTH = 32 ) 
   . price = models.DecimalField (= max_digits. 8, decimal_places = 2 ) 
   the authors = models.ManyToManyField (to = ' the Author ' , through = ' Book2Author ' , = through_fields ( ' book ' , ' author ' ))
 # through books tell django orm and author tables of many relationship is recorded by Book2Author to 
# through_fields tell django used book field Book2Author table when orm record and relationship author field to record 
"" " 
many to many fields in 
the Add 
the SET 
the Remove 
the Clear does not support 
"""
                
                
class Author(models.Model):
    name = models.CharField(max_length=32)
        # books = models.ManyToManyField(to='Book', through='Book2Author', through_fields=('author', 'book'))


class Book2Author(models.Model):
    book = models.ForeignKey(to='Book')
    author = models.ForeignKey(to='Author')
    create_time = models.DateField(auto_now_add=True)