Question

我的模特中有：

Email
    email Text
    user UserId Maybe
    verkey Text Maybe
    UniqueEmail email

我有一个表单，用户可以输入电子邮件（现有用户）和金额（int）。基于此电子邮件，我想找到该用户的UserId。我有声音：

paymentForm :: Form Payment
paymentForm = renderDivs $ Payment
    <$> lift (liftIO getCurrentTime)
    <*> pure userId
    <*> areq userIdField "To" Nothing
    <*> areq intField "Amount" Nothing
   where
    message :: Text
    message = "This user doesnt exist"
    userIdField = check hisUserId emailField
    hisUserId x | rawSql (SELECT user FROM "Email" WHERE "Email".email = x) == "" = Left message
                | otherwise = Right x

但这似乎不起作用。有什么想法吗？

Answer 1

rawSql不会将单个值作为字符串返回。相反，您可以使用Persistent实际查找电子邮件然后再决定。

我不知道为什么你的userId是一个Maybe。为什么你只有一个电子邮件ID而不是相应的用户ID？无论如何，我将假设这是一个必须保持简单的领域。

像（未经测试）的东西：

 hisUserId :: Text -> Bool
 hisUserId email = do
     res  <- runDB $ selectList [EmailEmail ==. email] []
     user <- entityVal res
     case user of
          Just u ->  return True   
             -- if you really want to treat user as a Maybe then 
             -- you can get it using (emailUser u) and then check for its existence  
          Nothing -> return False

根据电子邮件Yesod在数据库中查找userId

1 个答案: