這個光標爲什麼不能正常工作？

Question

你知道這個遊標爲什麼不起作用嗎？當我點擊「更多結果」時，不會顯示其他結果。謝謝。

if n==1: 
    query = Main.all() 
    query.filter("tag_list", s[0]) 
    query.order("-date") 
    cursor = self.request.get("cursor") 
    if cursor: query.with_cursor(cursor) 
    items = query.fetch(2) 
    cursor = query.cursor()    

    for item in items: 
     main_id = item.key().id()          
     self.response.out.write("""<p> 
     <a href="%s" target="_blank"><span id=large>%s</span></a> 
     <a href="/comment?main_id=%s"><span id="small">comments</span></a><br /> 
     %s <a href="/edit?main_id=%s&url_path=/searchhandler?search_string=%s"><span id="small">edit</span></a> 
     </p> 
     """ %   
     (item.url, item.title, main_id, 
     f1.truncate_at_space(item.pitch), main_id, search_string)) 

    self.response.out.write('<a href="/searchhandler?cursor=%s">More Results</a>' % cursor) 

編輯

As Dave W. Smith's answer的問題是與s從而改變光標被調用後。我在代碼下面粘貼日誌信息。

class SearchHandler(webapp.RequestHandler): 
    def get(self): 
... 
#-------search form--------#  
     self.response.out.write(""" 
<form name="search_form" action="/searchhandler" method="get"><br /> 
<input type="text" name="search_string" size=40> 
<input type="submit" value="search tags"> 
</form> """) 

     search_string = self.request.get("search_string") 

     s = filter(None, f1.striplist(self.request.get("search_string").split(" "))) 
     logging.info("""((((((s1: %s))))))""" % s) 
     # before cursor --> ((((((s1: [u'python'])))))) 
     # after cursor --> ((((((s1: [])))))) 
     n = len(s) 

     if n==1: 
      query = Main.all() 
      query.filter("tag_list", s[0]) 
      query.order("-date") 

      logging.info("""((((((s2: %s))))))""" % s) 
      #-->((((((s2: [u'python'])))))) 
      cursor = self.request.get("cursor") 
      if cursor: query.with_cursor(cursor) 
      items = query.fetch(2) 
      cursor = query.cursor() 
      related_tags = []    
      if items:      
       logging.info("""((((((s3: %s))))))""" % s) 
       #-->((((((s3: [u'python'])))))) 
       for item in items: 
        for tag in item.tag_list: 
         related_tags.append(tag) 
       unique_tags = sorted(f1.f2(related_tags)) 
       for tag in unique_tags: 
        self.response.out.write(""" 
        <a href="/rt?rt=%s">%s</a> | """ % 
        (tag, tag)) 
       self.response.out.write("""<br />""") 
       for item in items: 
        main_id = item.key().id()          
        self.response.out.write("""<p> 
        <a href="%s" target="_blank"><span id=large>%s</span></a> 
        <a href="/comment?main_id=%s"><span id="small">comments</span></a><br /> 
        %s <a href="/edit?main_id=%s&url_path=/searchhandler?search_string=%s"><span id="small">edit</span></a> 
        </p> 
        """ %   
        (item.url, item.title, main_id, 
        f1.truncate_at_space(item.pitch), main_id, search_string)) 
       self.response.out.write("""<a href="/searchhandler?cursor=%s">More Results</a>""" % cursor) 
       logging.info("""((((((s4: %s))))))""" % s) 
       # --> ((((((s4: [u'python'])))))) 
       self.response.out.write("""<br /><br />""") 
      else: 
       self.redirect("/nomatch") 

編輯2

問題解決了所建議由Dave史密斯：

class SearchHandler(webapp.RequestHandler): 
    def get(self):   
... 
     search_string = self.request.get("search_string") 

     if search_string: 
      s = filter(None, f1.striplist(self.request.get("search_string").split(" "))) 
      self.response.out.write(""" 
      <form name="search_form" action="/searchhandler" method="get"><br /> 
      <input type="text" name="search_string" size=40 value="%s"> 
      <input type="submit" value="search tags"> 
      </form> """ % search_string) 
     else: 
      ss = self.request.get("ss") 
      s = filter(None, f1.striplist(self.request.get("ss").split(" "))) 
      self.response.out.write(""" 
      <form name="search_form" action="/searchhandler" method="get"><br /> 
      <input type="text" name="search_string" size=40 value="%s"> 
      <input type="submit" value="search tags"> 
      </form> """ % ss) 

     n = len(s) 

     if n==1: 
      query = Main.all() 
      query.filter("tag_list", s[0]) 
      query.order("-date") 

      cursor = self.request.get("cursor") 
      if cursor: query.with_cursor(cursor) 
      items = query.fetch(7) 
      cursor = query.cursor() 

...      
       self.response.out.write("""<a href="/searchhandler?cursor=%s&ss=%s">More Results</a>""" % tuple([cursor, search_string])) 
...       

Answer 1

假設代碼是在處理程序中，是s[0]在每次調用相同的？遊標只能用於相同的聲明查詢。如果s[0]發生更改，則查詢更改，並且以前保存的光標將無法使用。