python – WTForms：在发布时将表单值传递回用户

发布时间：2020-12-20 13:29:11 所属栏目：Python 来源：网络整理

导读：当GET和POST方法都在同一个处理程序类中时,我想在表单验证失败后用用户输入填充表单字段,我这样做…… Class CommentHandler(BaseHandler): def get(self,form=None): if form is None: # create new form unless populated form is passed in form = Commen

当GET和POST方法都在同一个处理程序类中时,我想在表单验证失败后用用户输入填充表单字段,我这样做……

Class CommentHandler(BaseHandler):
    def get(self,form=None):
        if form is None: # create new form unless populated form is passed in
            form = CommentForm()
        # query DB and create template context
        self.render('page.html',**context)

    def post(self):
        form = CommentForm(self.request.POST)
        if form.validate():
            # populate entity with form data and save to DB
            return self.redirect_to('page')
        self.get(form=form) # pass populated form back to user for editing

我不知道这是否是将表单数据恢复给用户的最佳方式,但它似乎有效.我的问题是：如果GET和POST方法在不同的处理程序类中,如何将数据传回表单？

class PageHandler(BaseHandler):
    def get(self):
        # displays form to user

class CommentHandler(BaseHandler):
    def post(self):
        # processes POSTed form data...
        # but if form.validate() fails,# how can I pass the form data back to the user
        # so they can edit their form input?

解决方法

当您发布并调用validate()时,WTForms将表单编码数据绑定到Form实例. http POST可以像GET一样返回响应,这就是为什么当服务器应用程序验证失败并且您尝试刷新时,您有时会在浏览器中获取这些有趣的消息.这是因为刷新操作将调用GET处理管道,您将丢失POST数据.

您需要做什么而不是委托回get实现,您只需要从post实现中呈现一个响应,该响应将Form实例与绑定到它的数据一起传递回响应中.如果您以建议的方式设置了模板,则数据将自动显示在相应的字段中.下面是您的处理程序可能看起来的片段.

def post(self):

    form = CommentForm(self.request.POST)

    if form.validate():
        # populate entity with form data and save to DB
        return self.redirect_to('page')

    # If we are here it means we failed validation
    # We need to send back the data the use supplied 
    # with error messages so we can re-render the form
    # with their data and error messages indicating why
    # it was rejected.

    self.render('page.html',form=form) # pass populated form back to user for editing

这当然假设您的page.html知道如何处理Form实例.

（编辑：李大同）

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