Python Road _day71_django pagination and session Introduction

One, Django paging

The following examples are custom paging:

"""example of using the paging component: Def index (request): obj = pagination (request). Get.get (' page ', 1), Len (user_list), request.path_info) page_user_list = user_list[obj.start:obj.end] page_html = OBJ.PA Ge_html () return render (Request, ' index.html ', {' users ':p age_user_list, ' page_html ':p age_html})"""classpagination (object):def __init__(self,current_page,all_count,base_url,per_page_num=10,pager_count=11):        """encapsulates paging-related data:p Aram Current_page: Current page:p Aram All_count: Total number of data bars in the database:p Aram Per_page_num: per page Number of data bars displayed:p Aram base_url: URL prefixes displayed in pagination:p Aram Pager_count: The maximum number of pages displayed"""        Try: Current_page=Int (current_page)exceptException as E:current_page= 1ifCurrent_page <1: Current_page= 1Self.current_page=current_page Self.all_count=All_count Self.per_page_num=Per_page_num Self.base_url=Base_url#Total Page NumberAll_pager, TMP =Divmod (All_count, Per_page_num)ifTmp:all_pager+ = 1Self.all_pager=All_pager Self.pager_count=Pager_count self.pager_count_half= Int ((pager_count-1)/2) @propertydefStart (self):return(self.current_page-1) *Self.per_page_num @propertydefEnd (self):returnSelf.current_page *Self.per_page_numdefpage_html (self):#if the total number of pages < 11:        ifSelf.all_pager <=Self.pager_count:pager_start= 1Pager_end= Self.all_pager + 1#Total page Numbers >        Else:            #Current page If a maximum of 11/2 page numbers are displayed on the <= page            ifSelf.current_page <=Self.pager_count_half:pager_start= 1Pager_end= Self.pager_count + 1#The current page is greater than 5            Else:                #page number over to the end                if(Self.current_page + self.pager_count_half) >Self.all_pager:pager_end= Self.all_pager + 1Pager_start= Self.all_pager-self.pager_count + 1Else: Pager_start= Self.current_page-self.pager_count_half pager_end= self.current_page + self.pager_count_half + 1page_html_list=[] First_page='<li><a href= "%s?page=%s" > Home </a></li>'% (self.base_url,1,) page_html_list.append (first_page)ifSelf.current_page <= 1: Prev_page='<li><a href= "#" > Prev </a></li>'        Else: Prev_page='<li><a href= "%s?page=%s" > Prev </a></li>'% (self.base_url,self.current_page-1,) page_html_list.append (prev_page) forIinchRange (Pager_start, pager_end):ifi = =self.current_page:temp='<li class= "active" ><a href= "%s?page=%s" >%s</a></li>'%(Self.base_url,i, I,)Else: Temp='<li><a href= "%s?page=%s" >%s</a></li>'%(Self.base_url,i, I,) page_html_list.append (temp)ifSelf.current_page >=Self.all_pager:next_page='<li><a href= "#" > Next </a></li>'        Else: Next_page='<li><a href= "%s?page=%s" > Next </a></li>'% (Self.base_url,self.current_page + 1,) page_html_list.append (next_page) last_page='<li><a href= "%s?page=%s" > Last </a></li>'%(Self.base_url,self.all_pager,) page_html_list.append (last_page)return "'. Join (Page_html_list)

The page_html () function in the above class returns the string containing the Li tag in the page list, and replaces it in the corresponding HTML file in the following way:

function to get the string:

The string is converted into HTML:

Second, Session Introduction

1. Cookie and Session comparison

(a) A cookie is a key-value pair stored on the browser side, while the session is a key-value pair on the server side of the save, but relies on cookies.

(b) In the case of login, the cookie is a key-value pair set in clear text after successful login, and the key-value pair is sent to the client, the plaintext information may be leaking and unsafe; The session generates a random string, which is sent to the user and written to the browser's cookie, and the server also saves one copy.

(c) At the time of login verification, the cookie: determines the key value of the cookie that accompanies the request when the browser sends it, and if so, validates the pass; session: Gets a random string in the cookie of the requesting user, Validates the corresponding value in the session based on a random string

2, session of the classification

As above, according to the session in the server to save the location of the following 5 kinds:

(1) Database session

As the name implies, the session value is stored in the database, Django default support session, and the default is to store session data in the database, namely: Django_session table. Before using this type of session, you need to create a table for the session by executing the following two commands. As follows:

Python manage.py Makemigrationspython manage.py Migrate

The basic file configuration for this type of session is as follows, in the configuration settings in the setting.py file:

Session_engine ='django.contrib.sessions.backends.db'   #engine (default)session_cookie_name ="SessionID"                       #session's cookie is stored on the browser when the key, namely: Sessionid= random string (default)Session_cookie_path ="/"                               #The path of the session's cookie Save (default)Session_cookie_domain = None#Session cookie saved domain name (default)Session_cookie_secure = False#whether HTTPS transmits cookies (default)Session_cookie_httponly = True#whether the session's cookie only supports HTTP transport (default)Session_cookie_age = 1209600#session's cookie expiration date (2 weeks) (default)Session_expire_at_browser_close = False#whether to close the browser so that the session expires (default)Session_save_every_request = False#whether the session is saved every time the request is modified, and then saved (by default)

The session is used as follows:

Set up:

Get:

Delete:

defIndex (Request):#get, set, delete data in sessionrequest.session['K1'] Request.session.get ('K1', None) request.session['K1'] = 123Request.session.setdefault ('K1', 123)#exists then does not set        delrequest.session['K1']         #all keys, values, key-value pairsRequest.session.keys () request.session.values () Request.session.items () request.session.i Terkeys () request.session.itervalues () Request.session.iteritems ( )#random string for user sessionRequest.session.session_key#Delete all data with session expiration date less than current daterequest.session.clear_expired ()#Check if the random string in the user session is in the databaseRequest.session.exists ("Session_key")         #Delete all session data for the current userRequest.session.delete ("Session_key") Request.session.set_expiry (value)*if value is an integer, the session will expire after a few seconds. *if value is a datatime or timedelta,session, it will expire after this time. *if value is 0, the user closes the browser session and expires. * If value is none,session, it will depend on the global session expiration policy.

(2) Cache session

Use the same way, its configuration file content is as follows:

Configuring settings.py Session_engine='Django.contrib.sessions.backends.cache'  #engineSession_cache_alias ='default'                            #the cache alias used (the default memory cache, or memcache), where the alias relies on the cached settingssession_cookie_name ="SessionID"                        #session cookie is stored on the browser when the key, namely: Sessionid= random stringSession_cookie_path ="/"                                #The path of the session cookie saveSession_cookie_domain = None#session of the cookie saved by the domain nameSession_cookie_secure = False#whether HTTPS transmits cookiesSession_cookie_httponly = True#whether the session cookie only supports HTTP transmissionSession_cookie_age = 1209600#Cookie Expiration date for session (2 weeks)Session_expire_at_browser_close = False#whether to close the browser so that the session expiresSession_save_every_request = False#if the session is saved every time the request is modified, it is saved after the default

(3) File session

(4) cache + Database session

(5) Encryption Cookie session

Python Road _day71_django pagination and session Introduction