python練習六—簡單的論壇

時間 2019-11-17

原文原文鏈接

進行簡單的web應用以後，接下來就應該學習python鏈接數據庫，這個練習就是在上個練習的基礎上將信息保存到數據庫，這個聯繫也沒有什麼特別的，有以前java web的經驗的話，很好理解，主要仍是一個MySQLdb的學習。代碼以下（建立數據庫就忽略了吧）：html

從數據庫查詢message以列表的形式顯示main.pyjava

#! /usr/bin/env python
# -*- coding=utf-8 -*-

import cgitb
import MySQLdb

# 聲明文本格式
print 'Content-type:text/html\n'

cgitb.enable()

# 鏈接數據庫
conn = MySQLdb.connect(user='root', db='test')
curs = conn.cursor()

print """
<html>
  <head>
    <title>主頁</title>
  </head>
  <body>
    <h1>論壇帖子列表</h1>
"""

# 將數據庫中記錄讀取到dic
curs.execute('select * from messages')
# mysql沒有這樣的方法
# rows = curs.dictfetchall()
# 獲取表的列的名稱
names = [d[0] for d in curs.description]
print names
rows = [dict(zip(names, row)) for row in curs.fetchall()]
print rows

# 主貼
toplevel = []
# 回覆帖
children = {}

# 區分出主貼和回覆帖
for row in rows:
    parent_id = row['reply_to']
    if parent_id is None:
        toplevel.append(row)
    else:
        children.setdefault(parent_id, []).append(row)

# 格式化帖子列表
def format(row):
    print '<p><a href="view.py?id=%(id)s">%(subject)s </a></p>'% row
    try:
        kids = children[row['id']]
    except KeyError:
        pass
    else:
        # 遞歸格式化帖子的子貼（回覆）
        print '<blockquote>'
        for kid in kids:
            format(kid)
        print '</blockquote>'
print '<p>'


# 調用format格式化帖子
for row in toplevel:
    format(row)

print """
    </p>
    <hr />
    <p><a href="edit.py">發帖</a></p>
  </bofy>
</html>
"""

查看一個具體帖子的詳細內容view.pypython

#! /usr/bin/env python
# -*- coding=utf-8 -*-

import cgitb
import sys
import cgi
import MySQLdb

# 聲明文本格式
print 'Content-type:text/html\n'

cgitb.enable()

# 接受參數
form = cgi.FieldStorage()
id = form.getvalue('id')

try:
    id = int(id)
except :
    print 'Invalid id'
    sys.exit()

# 鏈接數據庫
conn = MySQLdb.connect(user='root', db='test')
curs = conn.cursor()

print """
<html>
  <head>
    <title>View message</title>
  </head>
  <body>
    <h1>View Message</h1>
"""

# 將數據庫中記錄讀取到dic
curs.execute('select * from messages where id = %i' % id)
# mysql沒有這樣的方法
# rows = curs.dictfetchall()
# 獲取表的列的名稱
names = [d[0] for d in curs.description]
#print names
rows = [dict(zip(names, row)) for row in curs.fetchall()]
#print rows

# 若是該id查詢不到數據，說明不存在該id
if not rows:
    print 'Unknow message id'
    sys.exit()

# 獲取返回的第一條數據
row = rows[0]

print """
    <p>
      <b> Subject: </b>%(subject)s <br />
      <b> sender: </b>%(sender)s <br />
      <pre>%(text)s</pre>
    </p>
    <hr />
    <a href="main.py">back to main page</a>>
    |
    <a href="edit.py?reply_to=%(id)s"> reply</a>
  </bofy>
</html>
""" % row

查看完帖子以後回帖，edit.pymysql

#! /usr/bin/env python
# -*- coding=utf-8 -*-

import cgitb
import sys
import cgi
import MySQLdb

# 聲明文本格式
print 'Content-type:text/html\n'

cgitb.enable()

# 接受參數
form = cgi.FieldStorage()
reply_to = form.getvalue('reply_to')

# 鏈接數據庫
conn = MySQLdb.connect(user='root', db='test')
curs = conn.cursor()

print """
<html>
  <head>
    <title>View message</title>
  </head>
  <body>
    <h1>View Message</h1>
    <form action="save.py" method="POST">
"""

subject = ''
if reply_to is not None:
    print "<input type='hidden' name='reply_to' value='%s' />" % reply_to
    curs.execute('select * from messages where id=%s' % reply_to)
    subject = curs.fetchone()[1]
    print subject
    if not subject.startswith('Re:'):
        subject = 'Re:'+ subject

print """
      <b>Subject:</b><br />
      <input type='text' size='40' name='subject' value='%s' /><br />
      <b>Sender:</b><br />
      <input type='text' size='40' name='sender' /><br />
      <b>Message:</b><br />
      <textarea name='text' cols='40' rows='20'></textarea><br />
      <input type='submit' value='Save'/>
    </form>
    <hr />
    <a href='main.py'>Back to the main page</a>'
  </body>
</html>
""" % subject

編輯完帖子的時候，提交save.pygit

#!/usr/bin/python
# -*- coding=utf-8 -*-

print 'Content-type: text/html\n'

import cgitb; cgitb.enable()

# 將單引號轉義，在使用insert語句的時候字符串就不須要添加引號
def quote(string):
    if string:
        return string.replace("'", "\\'")
    else:
        return string

import MySQLdb
conn = MySQLdb.connect(db='test', user='root')
curs = conn.cursor()

import cgi, sys
form = cgi.FieldStorage()

sender = quote(form.getvalue('sender'))
subject = quote(form.getvalue('subject'))
text = quote(form.getvalue('text'))
reply_to = form.getvalue('reply_to')

if not (sender and subject and text):
    print 'Please supply sender, subject, and text'
    sys.exit()

if reply_to is not None:
    query = """
    insert into messages(reply_to, sender, subject, text)
    values(%i, '%s', '%s', '%s')""" % (int(reply_to), sender, subject, text)
else:
    query = """
    insert into messages(sender, subject, text)
    values('%s', '%s', '%s')""" % (sender, subject, text)

curs.execute(query)
conn.commit()


print """
<html>
  <head>
    <title>Message Saved</title>
  </head>
  <body>
    <h1>Message Saved</h1>
    <hr />
    <a href='main.py'>Back to the main page</a>
  </body>
</html>s
"""

完整代碼web

http://pan.baidu.com/s/1gfbLDtxsql

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