Python 查看函数没有返回响应
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View function did not return a response
提问by saidozcan
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:
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：
@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]
It always says, view function did not return a response. What am I doing wrong?
它总是说，view function did not return a response。我究竟做错了什么？
采纳答案by Martijn Pieters
Flask throws this exception because your authview didn't return anything. Return a response from your authview:
Flask 抛出此异常是因为您的auth视图没有返回任何内容。从您的auth视图中返回响应：
return 'Some response'
To return the MySQL results, perhaps join the rows together into one string:
要返回 MySQL 结果，也许将行连接成一个字符串：
cur.execute("SELECT * FROM tbl_user WHERE username = '%s' " % username)
return '\n'.join([', '.join(r) for r in cur])
or define a template and return the rendered template.
或者定义一个模板并返回渲染的模板。
Note that you really do not want to use string interpolation for your usernameparameter, especiallyin a web application. Use SQL parameters instead:
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：
cur.execute("SELECT * FROM tbl_user WHERE username = %s", (username,))
Now the database client will do the quoting for you and prevent SQL injection attacks. If you use string interpolation, this will happen.
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，就会发生这种情况。
(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.)
（如果这是一个不错的数据库（例如不是 MySQL），则该数据库可以采用现在通用的 SQL 语句并为其创建一个查询计划，然后在多次执行该查询时一次又一次地重复使用该计划；使用字符串插值你d 防止这种情况。）
