Why am i getting TypeError: object of type 'NoneType' has no len() error (practically copied code from a working part of my code)

Question

我对整个编程这件事还很陌生。目前，我正在开发一个烧瓶，python，SQLite 项目。我设置了一个编辑表单来编辑用户发布的列表。效果很好。然后我复制了该代码以为其创建用户信息编辑表单，现在我收到 TypeError: object of type 'NoneType' has no len() with essentially exact same code.

HTML 代码。如果这意味着什么，此代码位于 modal 内。

<form action="/edituserinfo" method="post">
                        <label for="name" style="float:left">Name:</label><br />
                        <input class="form-control" name="name" style="width:100%" placeholder="{{ user[0]['username'] }}">
                        <label for="email" style="float:left">Email:</label><br />
                        <input class="form-control" name="email" style="width:100%" placeholder="{{ user[0]['email'] }}">
                        <label for="city" style="float:left">City:</label><br />
                        <input class="form-control" name="city" style="width:100%" placeholder="{{ user[0]['city'] }}">
                    <button type="submit" class="btn btn-lg btn-success btn-block">SAVE!</button>
                </form>

这是我的 python 代码。

@app.route("/edituserinfo", methods=["GET", "POST"])
@login_required
def edituserinfo():

    if request.method == "POST":
        user = session["user_id"]
        column = ["username", "email", "city"]
        for title in column:
            if len(request.form.get(title)) != 0:
                value = request.form.get(title)
                db.execute("UPDATE users SET %s = :edit WHERE id = :id" %(title), {"edit":value, "id":user})
                db.commit()
        return redirect("/account")

    else:
        return redirect("/account")

任何帮助，建议将不胜感激！！谢谢！

Answer 1

错误的产生是因为request.form.get("username") returns None.

这是因为 "username" 不是您显示的 HTML 中的表单元素之一 - 我认为您想要 "name"，即

column = ["name", "email", "city"]

Why am i getting TypeError: object of type 'NoneType' has no len() error (practically copied code from a working part of my code)

Why am i getting TypeError: object of type 'NoneType' has no len() error (practically copied code from a working part of my code)

html

python

modal-dialog

request.form