烧瓶自定义验证错误-TypeError:不支持的类型“<class'wtforms.fields.core.UnboundField'>”

因此,我的目标是在验证表单时检查dynamodb表中的值是否存在。

def pipeline_exists(self, pipeline_name):
    ses = boto3.session.Session()
    try:
        dynamodb = ses.resource('dynamodb')
    except Exception as exception:
        message = 'Error on DynamoDB client'
        logging.error("Dynamodb client session failed: %d %s", exception)
        msg = " Dynamodb client session failed: " + str(exception)

        raise exception
    table_name = 'my_tbl'
    table = dynamodb.Table(table_name)

    response = table.query(
        KeyConditionExpression=Key('pipeline_name').eq(pipeline_name)
    )

    print(response)
    if response['count'] > 0:
        raise validators.ValidationError('Pipeline ' + pipeline_name.data + ' already exists')
    else:
        True

class AddPipeline(Form):
    pipeline_name = StringField('Pipeline Name', [validators.Length(min=10, max=250), pipeline_exists])

我得到的错误是:

TypeError: Unsupported type "<class 'wtforms.fields.core.UnboundField'>" for value "<UnboundField(StringField, (), {})>"