flask之jinja2.exceptions.UndefinedError : 'str object' has no attribute 'username'

我在尝试加载 register.html 页面时无法让我的 flask 应用程序识别我的表单变量。我试图重新加载我的 virtualenv 并尝试从另一个人那里加载模板代码，但我得到了同样的错误。这是我得到的回溯。

File "s:\projects\gameapp\env\lib\site-packages\flask\app.py", line 2309, in __call__ 
return self.wsgi_app(environ, start_response) 
File "s:\projects\gameapp\env\lib\site-packages\flask\app.py", line 2295, in wsgi_app 
response = self.handle_exception(e) 
File "s:\projects\gameapp\env\lib\site-packages\flask\app.py", line 1741, in handle_exception 
reraise(exc_type, exc_value, tb) 
File "s:\projects\gameapp\env\lib\site-packages\flask\_compat.py", line 35, in reraise 
raise value 
File "s:\projects\gameapp\env\lib\site-packages\flask\app.py", line 2292, in wsgi_app 
response = self.full_dispatch_request() 
File "s:\projects\gameapp\env\lib\site-packages\flask\app.py", line 1815, in full_dispatch_request 
rv = self.handle_user_exception(e) 
File "s:\projects\gameapp\env\lib\site-packages\flask\app.py", line 1718, in handle_user_exception 
reraise(exc_type, exc_value, tb) 
File "s:\projects\gameapp\env\lib\site-packages\flask\_compat.py", line 35, in reraise 
raise value 
File "s:\projects\gameapp\env\lib\site-packages\flask\app.py", line 1813, in full_dispatch_request 
rv = self.dispatch_request() 
File "s:\projects\gameapp\env\lib\site-packages\flask\app.py", line 1799, in dispatch_request 
return self.view_functions[rule.endpoint](**req.view_args) 
File "S:\Projects\gameapp\gameapp.py", line 35, in register 
return render_template('register.html', title='Register', form='form') 
File "s:\projects\gameapp\env\lib\site-packages\flask\templating.py", line 135, in render_template 
context, ctx.app) 
File "s:\projects\gameapp\env\lib\site-packages\flask\templating.py", line 117, in _render 
rv = template.render(context) 
File "s:\projects\gameapp\env\lib\site-packages\jinja2\asyncsupport.py", line 76, in render 
return original_render(self, *args, **kwargs) 
File "s:\projects\gameapp\env\lib\site-packages\jinja2\environment.py", line 1008, in render 
return self.environment.handle_exception(exc_info, True) 
File "s:\projects\gameapp\env\lib\site-packages\jinja2\environment.py", line 780, in handle_exception 
reraise(exc_type, exc_value, tb) 
File "s:\projects\gameapp\env\lib\site-packages\jinja2\_compat.py", line 37, in reraise 
raise value.with_traceback(tb) 
File "S:\Projects\gameapp\templates\register.html", line 1, in top-level template code 
{% extends "layout.html" %} 
File "S:\Projects\gameapp\templates\layout.html", line 44, in top-level template code 
{% block content %}{% endblock %} 
File "S:\Projects\gameapp\templates\register.html", line 9, in block "content" 
{{ username.label(class="form-control-label") }} 
File "s:\projects\gameapp\env\lib\site-packages\jinja2\environment.py", line 430, in getattr 
return getattr(obj, attribute) 

这是我的registration.html页面

{% extends "layout.html" %} 
{% block content %} 
    <div class="content-section"> 
        <form method="POST" action=""> 
            {{ form.hidden_tag }} 
            <fieldset class="form-group"> 
                <legend class="border-bottom mb-4">Join Today</legend> 
                <div class="form-group"> 
                    {{ form.username.label(class="form-control-label") }} 
                    {{ form.username(class="form-control form-control-lg") }} 
                </div> 
                <div class="form-group"> 
                    {{ form.email.label(class="form-control-label")}} 
                    {{ form.email(class="form-control form-control-lg")}} 
                </div> 
                <div class="form-group"> 
                    {{ form.password.label(class="form-control-label") }} 
                    {{ form.password(class="form-control form-control-lg") }} 
                </div> 
                <div class="form-group"> 
                    {{ form.confirm_password.label(class="form-control-label") }} 
                    {{ form.confirm_password(class="form-control form-control-lg") }} 
                </div> 
            </fieldset> 
            <div class="form-group"> 
                {{ form.submit(class="btn btn-outline-info") }} 
            </div> 
        </form> 
    </div> 
    <div class="border-top pt-3"> 
        <small class="text-muted"> 
            Already Have An Account? <a class="ml-2" href="{{ url_for('login') }}">Sign In</a> 
        </small> 
    </div> 
{% endblock content %} 

我试图删除它引发错误的代码，我只是在下一行得到一个错误，说没有属性'email'，我认为它与版本错误有关，因为除了这个之外一切正常(目前)。任何帮助，将不胜感激。

请您参考如下方法:

您需要使用“class_”属性来标记，而不是“class”，这意味着您需要修复

{{ form.username.label(class="form-control-label") }} 

到

{{ form.username.label(class_="form-control-label") }} 

等等整个模板。