查看函数没有返回响应

问题描述

我想向 mysql 发送一个查询并获取一个数组.但是无论我怎么做，我都无法让它发挥作用.这是我的代码:

I want to send a query to mysql and fetch an array. But however I do it I cannot make it work. Here's my code:

@app.route('/auth',methods=['GET','POST'])
def auth():
    username = request.form['username']
    password = request.form['password']

    cur = db.cursor()
    cur.execute("SELECT * FROM tbl_user WHERE username = '%s' " % username)

    results = cur.fetchall()

    for row in results:
        print row[0]

它总是说，view 函数没有返回响应.我做错了什么?

It always says, view function did not return a response. What am I doing wrong?

推荐答案

Flask 抛出此异常，因为您的 auth 视图没有返回任何内容.从您的 auth 视图返回响应:

Flask throws this exception because your auth view didn't return anything. Return a response from your auth view:

return 'Some response'

要返回 MySQL 结果，可以将行合并为一个字符串:

To return the MySQL results, perhaps join the rows together into one string:

cur.execute("SELECT * FROM tbl_user WHERE username = '%s' " % username)
return '
'.join([', '.join(r) for r in cur])

或者定义一个模板并返回渲染的模板.

请注意，您确实不想对 username 参数使用字符串插值，尤其是在 Web 应用程序中.改用 SQL 参数:

Note that you really do not want to use string interpolation for your username parameter, especially in a web application. Use SQL parameters instead:

cur.execute("SELECT * FROM tbl_user WHERE username = %s", (username,))

现在数据库客户端将为您进行引用并防止 SQL 注入攻击.如果您使用字符串插值，会发生这种情况.

Now the database client will do the quoting for you and prevent SQL injection attacks. If you use string interpolation, this will happen.

(如果这是一个不错的数据库(例如不是 MySQL)，该数据库可以采用现在通用的 SQL 语句并为其创建查询计划，然后在多次执行该查询时重复使用该计划；使用字符串插值，你会阻止.)

(If this was a decent database (e.g. not MySQL) the database could take the now-generic SQL statement and create a query plan for it, then reuse the plan again and again as you execute that query multiple times; using string interpolation you'd prevent that.)

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