第26章 项目7:自定义公告板

1.问题

如何创建通过Web发布和回复信息的简单系统,可以看作网络论坛。

2.工具

  1. CGI工具
  2. SQL数据库:PostgreSQL

    下载地址:

    http://www.enterprisedb.com/products-services-training/pgdownload#windows

    点击安装:

    Password设置为123456Port默认为5432

    (3)psycopg:与PostgrelSQL数据库通信的API模块。

    下载地址:http://www.stickpeople.com/projects/python/win-psycopg/

    注意Python postgrelSQL的版本号,点击安装:

    使用命令:import psycopg2 ,未报错,安装成功。

    3.准备工作——创建数据库

    打开SQL Shell(psql)PostgrelSQL命令行模式

    回车直到出现"用户 postgres 的口令:",输入密码123456并回车。

    26-1 PostgreSQL内创建数据库

    输入:

    (1)create database mytable;并回车,创建DATABASE

    (2)\c mytable;并回车连接到数据库"mytable",用户"postgres"

    (3)

    CREATE TABLE messages (

    id SERIAL PRIMARY KEY,

    subject TEXT NOT NULL,

    sender TEXT NOT NULL,

    reply_to INTEGER REFERENCES messages,

    text TEXT NOT NULL

    );

    并回车,出现CREATE TABLE,成功创建数据库。

    (4)\d并回车,显示出关联列表。

    拥有5个字段,

    Id:用于标识唯一的消息

    Subject:包括消息主体的字符串

    Sender:包括发送者名字、EMAIL地址或者其他信息的字符串

    Reploy_to:如果消息是回复其他消息的、那么这个字段就包括那个消息的ID

    Text:包括消息内容的字符串。

    (5)补充——数据库删除:

    1)\l

    2)DROP DATABASE mytable;

    4.初次实现

    一个简单测试,顺序输入:

    import psycopg2

    conn = psycopg2.connect('user=postgres password=123456 dbname=mytable')

    curs = conn.cursor()

    curs.execute('select * from messages')

    curs.fetchall()

    输出为[],由于数据库现在是空的,所以什么都没有得到。

    因为没有实现web接口,测试数据库需要手动输入消息。通过数据库管理工具可以添加消息,或者使用python解释器和数据库模块实现:

    addmessage.py

    #!D:\Program Files\python27\python.exe
    # addmessage.py
    import psycopg2
    conn = psycopg2.connect('user=postgres password=123456 dbname=mytable')
    curs = conn.cursor()

    reply_to = raw_input('Reply to: ')
    subject = raw_input('Subject: ')
    sender = raw_input('Sender: ')
    text = raw_input('Text: ')
    if reply_to:
    query = """
    INSERT INTO messages(reply_to, sender, subject, text)
    VALUES(%s, '%s', '%s','%s') """
    % (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()

    输入以下内容,成功写入数据库。

    测试后输出如下:

    26-4 simple_main.cgi ——主电子公告板

    #!D:\Program Files\python27\python.exe

    print 'Content-type: text/html\n'
    import cgitb; cgitb.enable()

    import psycopg2
    conn= psycopg2.connect('dbname=mytable user=postgres password=123456')
    curs= conn.cursor()

    print"""
    <html>
    <head>
    <title>The FooBar Bulletin Board</title>
    </head>
    <body>
    <h1>The FooBar BulletinBoard</h1>
    """

    curs.execute('SELECT * FROM messages')
    rows= curs.fetchall()

    toplevel= []
    children= {}

    for row in rows:
    parent_id = row['reply_to']
    if parent_id is None:
    toplevel.append(row)
    else:
    children.setdefault(parent_id,[]).append(row)

    def format(row):
    print row['subject']
    try: kids = children[row['id']]
    except KeyError: pass
    else:
    print '<blockquote>'
    for kid in kids:
    format(kid)
    print '</blockquote>'

    print '<p>'

    for row in toplevel:
    format(row)

    print"""
    </p>
    </body>
    </html>
    """

    放在D:\Program Files\Apache24\htdocs目录中(上一章所有文件已经删除了)。

    输入地址:http://localhost/simple_main.cgi

    5.再次实现

    26-5 main.cgi ——电子公告板主页

    #!D:\Program Files\python27\python.exe

    print 'Content-type: text/html\n'
    import cgitb; cgitb.enable()

    import psycopg2
    conn= psycopg2.connect('dbname=mytable user=postgres password=123456')
    curs= conn.cursor()

    print"""
    <html>
    <head>
    <title>The FooBar Bulletin Board</title>
    </head>
    <body>
    <h1>The FooBar BulletinBoard</h1>
    """

    curs.execute('SELECT * FROM messages')
    rows= curs.fetchall()
    toplevel= []
    children= {}

    for row in rows:
    parent_id = row[3]
    if parent_id is None:
    toplevel.append(row)
    else:
    children.setdefault(parent_id,[]).append(row)

    def format(row):
    print '<p><a href="view.cgi?id=%i">%s<a>' % (row[0],row[1])
    try:
    kids = children[row[0]]
    except KeyError:
    pass
    else:
    print '<blockquote>'
    for kid in kids:
    format(kid)

    print '</blockquote>'

    print '<p>'

    for row in toplevel:
    format(row)

    print"""
    </p>
    <hr/ >
    <p><a href="edit.cgi">Post Message</a></p>
    </body>
    </html>
    """

    26-6 view.cgi ——消息浏览

    #!D:\Program Files\python27\python.exe

    print 'Content-type: text/html\n'
    import cgitb; cgitb.enable()

    import psycopg2
    conn= psycopg2.connect('dbname=mytable user=postgres password=123456')
    curs= conn.cursor()

    import cgi, sys
    form = cgi.FieldStorage()
    id = form.getvalue('id')

    print '''
    <html>
    <head>
    <title>View Message</title>
    </head>
    <body>
    <h1>View Message</h1>
    '''

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

    curs.execute('SELECT * FROM messages WHERE id = %i' % id)
    rows = curs.fetchall()

    if not rows:
    print 'Unknown message ID'
    sys.exit()

    row = rows[0]

    print '''
    <p><b>Subject:</b> %s<br/>
    <b>Sender:</b>%s<br/>
    <pre>%s</pre>
    </p>
    <hr/>
    <a href='main.cgi'>Back to the main page</a>
    |<a href="edit.cgi?reply_to=%s">Reply</a>
    </body>
    </html>
    ''' % (row[1],row[2],row[4],row[0])

    26-7 edit.cgi ——消息编辑器

    #!D:\Program Files\python27\python.exe

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

    import cgitb; cgitb.enable()

    import psycopg2
    conn= psycopg2.connect('dbname=mytable user=postgres password=123456')
    curs= conn.cursor()
    import cgi,sys
    form = cgi.FieldStorage()
    reply_to = form.getvalue('reply_to')

    print '''
    <html>
    <head>
    <title>Compose Message</title>
    </head>
    <body>
    <h1>Compose Message</h1>

    <form action='save.cgi' method='POST'>
    '''

    subject = ''
    if reply_to is not None:
    print '<input type="hidden" name="reply_to" value="%s"/>' % reply_to
    curs.execute('SELECT subject FROM messages WHERE id = %s' % reply_to)
    subject = curs.fetchone()[0]
    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.cgi'>back to the main page</a>
    </body>
    </html>
    ''' % subject

    26-8 save.cgi ——实现保存的脚本

    #!D:\Program Files\python27\python.exe
    print 'Content-type:text/html\n'

    import cgitb;cgitb.enable()

    def quote(string):
    if string:
    return string.replace("'","\\'")
    else:
    return string

    import psycopg2
    conn= psycopg2.connect('dbname=mytable user=postgres password=123456')
    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,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 Save</title>
    </head>
    <body>
    <h1>Message Saved</h1>
    <hr />
    <a href='main.cgi'>Back to the main page</a>
    </body>
    </html>s
    '''

    将脚本main.cgiview.cgiedit.cgisave.cgi放在D:\Program Files\Apache24\htdocs目录中:

    输入地址:http://localhost/main.cgi

    点击Post Message,输入

    SubjectMr. Gumby is in town

    SenderMr. Gumby

    MessageYes, the romors are true. I have arrived.

    点击保存:

    返回主页:

    点击Mr. Gumby is in town,出现view界面:

posted @ 2016-12-04 20:16  Sumomo  阅读(760)  评论(0编辑  收藏  举报