How to analyze a pair of N Relations in django models
This article shows you how to analyze a pair of N relationships in django models. The content is concise and easy to understand, which will definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.
The following describes a pair of N relationships in the three relationship models of django models:
A pair of N models
In Django language, the 1 N relationship is accomplished by setting a foreign key reference to the 'main table' in the 'schedule'. At the SQL model layer, foreign keys can be defined with fields of type models,Foreignkey.
''
Content classification table
''
Class concat (models.Model):
# Category id
Id = models.BigAutoField (primary_key=True)
# when the parent category ID=0, it represents the first level category
Parent_id = models.BigIntegerField (default=0)
# first name
Name = models.CharField (max_length=50)
# status (optional values: 1 (normal), 2 (delete))
Status = models.IntegerField (default=1)
# arrange the sequence number to indicate the order in which the purposes of the sibling class are displayed, or in the order of name if the values are equal. Value range: integers greater than zero
Sort_order = models.IntegerField (default=1)
# whether this category is the parent category, 1 is true,0 and false
Is_parent = models.SmallIntegerField (default=1)
# creation time
Created = models.DateTimeField (auto_now_add=True)
# Update time
Updated = models.DateTimeField (auto_now=True)
''
Content table
''
Class content (models.Model):
# content id
Id = models.AutoField (primary_key=True)
# Category id
Cid = models.ForeignKey (concat, on_delete=models.CASCADE)
# title
Title = models.CharField (max_length=1000)
# subtitle
Sub_title = models.CharField (max_length=1000)
# title description
Title_desc = models.CharField (max_length=500)
# Link
Url = models.CharField (max_length=500)
# the absolute path of the picture
Pic = models.CharField (max_length=300)
# content
Content = models.TextField (default= "")
# creation time
Created = models.DateTimeField (auto_now_add=True)
# Update time
Updated = models.DateTimeField (auto_now=True)
The only difference between the above code and the one-to-one relationship is that the cid field in the content model is defined with models.ForeignKey. So that each concat object can be associated with multiple content objects
Queinfo = que_info.objects.all ()
For quein queinfo:
QueCat = que.cid.name
# get the master object by attaching it
Print que.cid
Print queCat
His master object can be obtained directly by clicking 'cid', that is, a foreign key.
A = que_cat.objects.all ()
For a1 in a:
A1.que_info_set
# getting the attached object through the main object is how to analyze the pair of N relations in django models. Have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.
