WTForms:测试是否填写字段 [英] WTForms: test whether field is filled out

问题描述

我在WTForms中遇到了一个我认为很简单的任务，即遇到麻烦:检查某个字段是否在其中输入了任何数据.似乎该数据方法根据字段的类型返回不同的结果，因此我不能泛泛地使用它来对此进行测试.

I'm having trouble with what I thought would be a very simple task in WTForms: checking to see if a field has had any data entered in it. It seems that the data method returns different results depending on the type of field, so I can't use it generically to test this.

我正在Flask应用程序中使用它.在我的表单声明中，我有:

I'm using this in a Flask app. In my forms declaration, I have:

title = StringField('Title')
signed = RadioField('Signed?', choices = [('Y','yes'),('N','no')])

然后，在我的views.py中，在"if form.is_submitted()"之后:

Then, in my views.py, after an "if form.is_submitted()":

print('Title raw_data is %r' % form.title.raw_data)
print('Title data is %r' % form.title.data)
if form.title.raw_data:
    print ("Title raw data is True")
if form.title.data:
    print ("Title data is True")

 print('Signed raw_data is %r' % form.signed.raw_data)
 print('Signed data is %r' % form.signed.data)
 if form.signed.raw_data:
     print ("Signed raw data is True")
 if form.signed.data:
     print ("Signed data is True")

运行此命令并填写表单中的任何字段时，我得到:

When I run this and fill out neither field in the form, I get:

Title raw_data is ['']
Title data is ''
Title raw data is True
Signed raw_data is []
Signed data is 'None'
Signed data is True

即form.title.data返回空字符串，因此我可以将其用于测试；form.signed.data返回字符串"None"，而不是None，因此它无法通过"if form.signed.data"测试.因此，我必须使用form.signed.raw_data，它返回一个空列表，即False.但是我不能在所有实例中都使用raw_data，因为form.title.raw_data不会返回空列表，它会返回由空字符串组成的列表，该字符串为 not True

That is, form.title.data returns the empty string, so I can use this for a test; form.signed.data returns the string 'None', rather than None, so it fails the "if form.signed.data" test. Thus I have to use form.signed.raw_data, which returns an empty list, which is False. But I can't use raw_data in all instances, because form.title.raw_data doesn't return an empty list, it returns a list consisting of the empty string, which is not True

有没有一种方法可以测试是否填写了任何类型的字段，或者我必须根据字段的类型在数据和raw_data之间切换?这是违反直觉和令人困惑的.

Is there a way I can test if any kind of field is filled out, or do I have to switch between data and raw_data depending on the kind of field? This is counterintuitive and confusing.

推荐答案

在 raw_data 中，表单字段的值为

In raw_data, values for a form field are collected in a list.

您要使用 data ，因为其值为

You want to work with data because its value is processed to its python representation. Most fields subclassing wtforms.fields.core.Field implements their own process_formdata method which fulfills this.

首先实现一个帮助程序功能，该功能可以像这样检查字段数据:

Start by implementing a helper function that checks field data like so:

def is_filled(data):
   if data == None:
      return False
   if data == '':
      return False
   if data == []:
      return False
   return True

请注意，如果在字段模式中指定了默认值，则数据会开始设置为默认值.在这种情况下，使用 raw_data 更为正确.

Note that data starts out set to the default value if a default value is specified in the field schema. In this case using raw_data is more correct.

def is_filled(raw_data):
   try:
       value = raw_data[0]
       if value == '':
          return False
   except (IndexError, TypeError):
       return False
   return True

测试:

>>> is_filled(None)
False
>>> is_filled([])
False
>>> is_filled(['',]) 
False

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