Summarize django knowledge points

1. View functions:

Request Object------------- request:

1,HttpRequest.body:) Request original data

2,HttpRequest.path:) A string representing the requested path component (without domain name)

          3,HttpRequest.method  

          4,HttpRequest.GET

          5,HttpRequest.POST

          6,HttpRequest.FILES

7,HttpResquest.user:) An AUTH_USER_Objects of type MODEL

- Response object:

return. HttpResponse(")] Returns an instance of a string

return render(request,"template", {":"}) return string instance

return Redirect ("/index/") Redirect

2. Template Language

First write the function in the views view function and return a rendering page:

      views:

              def foo (request): 

                   name="li"

                   l=[111,2222,3333]

                  d={"info":[obj1,obj2...]}

                  return  render(request,"index.html",locals())

Variable: {{name}}

------- Deep query period character. For example: {{d.info.0.name}

------- Filter {{name|date:'Y-m-d'}}

2. Tags:

for loop

          {%for i in l%}

             {{i}}

          {%empty%}

<p>There are no qualifications </p>

          {%endfor%}       

if statement

          {%if name="li"%}

             <p> Yes</p>

          {%elif%}

          {%endif....%}

3. Template Syntax

(1) In masterBase.html: {%block con%}{%endblock%}

(2) Inherit the masterIndex.html:

{%extends"Base.html"%}" Inheritance

                                                {%block con%}

                                                {%endblock%}

3. models Model of ORM

1. Mapping relationship:

Table Name in sql----------Class Name of Python

Fields in sql--------Class properties of Python

Records in sql------Class objects for Python

2. Form operation

class Article(models.Model):
            nid = models.BigAutoField(primary_key=True)
            title = models.CharField(max_length=50, verbose_name='Article Title')
            read_count = models.IntegerField(default=0)

(1) Add operation

      views:

 

 #Method 1:
      article_obj=models.Article.objects.create(nid=1,title="yuan",read_count=12) # create Method returns the currently created article object
 #Method 2:
      article_obj=models.Article(nid=1,title="yuan",read_count=12)
      article_obj.save()
                   
  //Delete:
      models.Article.objects.filter(title="python").delete()  #  Default Cascade Delete
       
  //Modify:
      models.Article.objects.filter(title="python").update(read_count=F("read_count")+10)

 //Query API:
          <1> all():                            Query all results   #QuerySet
 
                    <2> filter(**kwargs):        It contains objects that match the given filter criteria  #QuerySet
                     
                    <3> get(**kwargs):     Returns the object that matches the filter criteria given. There is one and only one result.
                                               //An error is thrown if more than one or none of the objects meet the filter criteria.# model object
                     
                    <5> exclude(**kwargs):     It contains objects that do not match the given filter criteria  #QuerySet 
                     
                    <4> values(*field):     Return a ValueQuerySet-A special QuerySet,What you get after running is not a series
                                               model Instantiate an object, but an iterative sequence of dictionaries   #QuerySet
                     
                    <9> values_list(*field):        It is associated with values()Very similar, it returns a tuple sequence. values A dictionary sequence is returned #QuerySet
                     
                    <6> order_by(*field):         Sort query results #QuerySet
                     
                    <7> reverse():                  Reverse sort of query results #QuerySet
                     
                    <8> distinct():                Remove duplicate records from returned results #QuerySet
                     
                    <10> count():                Return matching queries in database(QuerySet)Number of objects. # int
                     
                    <11> first():                  Return the first record       # model object
                     
                    <12> last():                  Return to the last record     # model object
                     
                    <13> exists():   If QuerySet Contains data, returns True,Otherwise return False
                    
                    querySet Support chain operation:
                           models.Article.objects.all().filter().values().distinct().count()
                           
                    QuerySet Data type:
                        1,Sliceable, iterative      [obj,....]  
                        2,Lazy queries:
                                 articles_list=models.Article.objects.all()
                                 //Using articles_list, such as if articles_list, convert the sql statement at this time                 

                        3,Caching mechanism
                                 articles_list=models.Article.objects.all()
                                 for i in articles_list: 
                                        print(i.title)     # hit the database
                                 
                                 for i in articles_list: 
                                        print(i.title)     # not hit the database    

                                 ==============================================
                                 for i in models.Article.objects.all(): 
                                        print(i.title)     # hit the database
                                 
                                 for i in models.Article.objects.all(): 
                                        print(i.title)     #  hit the database    
                        4,Optimize Query
                                 articles_list=models.Article.objects.all().iterator()
                                 for i in articles_list: 
                                        print(i.title)     # hit the database
                                        
                                                                 for i in articles_list: 
                                        print(i.title)     # No result            
                                                        
        //Join Table Operation:
                
                //Table relations:
                        
                       class UserInfo(AbstractUser):  # settings:   AUTH_USER_MODEL = "blog.UserInfo"
                            """
                            //User Information
                            """
                            nid = models.BigAutoField(primary_key=True)
                            nickname = models.CharField(verbose_name='Nickname?', max_length=32,null=True)
                            telephone = models.CharField(max_length=11, blank=True, null=True, unique=True, verbose_name='Phone number')
                            avatar = models.FileField(verbose_name='Head portrait', upload_to='avatar', default="avatar/default.png")
                            create_time = models.DateTimeField(verbose_name='Creation Time', auto_now_add=True)

                        class Blog(models.Model):
                            """
                            //Site Information
                            """
                            nid = models.BigAutoField(primary_key=True)
                            title = models.CharField(verbose_name='Personal Blog Title', max_length=64)
                            site = models.CharField(verbose_name='Personal Blog Suffix', max_length=32, unique=True)
                            theme = models.CharField(verbose_name='Blog Theme', max_length=32)

                            user = models.OneToOneField(to='UserInfo', to_field='nid')    

                        class Category(models.Model):
                            
                            nid = models.AutoField(primary_key=True)
                            title = models.CharField(verbose_name='Category Title', max_length=32)
                            blog = models.ForeignKey(verbose_name='Owning Blog', to='Blog', to_field='nid')
         
                        class Article(models.Model):
                            nid = models.BigAutoField(primary_key=True)
                            title = models.CharField(max_length=50, verbose_name='Article Title')
                            desc = models.CharField(max_length=255, verbose_name='Article Description')
                            
                            # category Field: and Article Object-Associated category object
                            category = models.ForeignKey(verbose_name='Article Type', to='Category', to_field='nid', null=True)
                            
                            # user Field: and Article Object-Associated user field
                            user = models.ForeignKey(verbose_name='Owned User', to='UserInfo', to_field='nid')
                            
                            tags = models.ManyToManyField(
                                to="Tag",
                                through='Article2Tag',
                                through_fields=('article', 'tag'),
                            )

                            
                        class ArticleDetail(models.Model):
                            
                            nid = models.AutoField(primary_key=True)
                            content = models.TextField(verbose_name='Article Content', )

                            article = models.OneToOneField(verbose_name='Owned Articles', to='Article', to_field='nid')
                        
                        class Article2Tag(models.Model):
                            nid = models.AutoField(primary_key=True)
                            article = models.ForeignKey(verbose_name='Article', to="Article", to_field='nid')
                            tag = models.ForeignKey(verbose_name='Label', to="Tag", to_field='nid')
                        
                        
                        class Tag(models.Model):
                            nid = models.AutoField(primary_key=True)
                            title = models.CharField(verbose_name='Label Name', max_length=32)
                            blog = models.ForeignKey(verbose_name='Owning Blog', to='Blog', to_field='nid'
                            
                        
                //Add record operation to associated table:
                        1,Create an article for:
                           user_obj=models.UserInfo.objects.get(nid=1)
                           category_obj=models.Category.objects.get(nid=2)
                           
                           
                           #################One-to-many relationship binding#########################
                           # Mode 1:
                           article_obj=models.Article.objects.create(nid=5,title="Pick up flowers at night"....,user=user_obj,category=category_obj)
                           
                           # Mode 2:
                            article_obj=models.Article.objects.create(nid=5,title="Pick up flowers at night"....,user_id=1,category_id=2)
                           '''
                               Article:
                                         nid         title        user_id     category_id
                                          5         Pick up flowers at night        1              2
                                           
                           '''

Tags: Python Database SQL

Posted on Sun, 19 Jul 2020 10:56:54 -0400 by bluetonic