[英]How get the user ID from the Session at (Yesod / Haskell Project
伙計們,我有一個項目,我需要從Session中引出用戶的ID。
我不能將其放在Text / Int中,因為它說會話帶有密鑰(我認為是Sql Key),我如何將其轉換為Int以在項目中的其他方法中使用
我試圖這樣做以從會話中恢復ID
getInicioR :: Handler Html
getInicioR = do
uid <- lookupSession "_ID"
user <- runDB $ get404 uid
顯示以下錯誤消息:
Couldn't match expected type ‘Key t0’ with actual type ‘Maybe Text’
In the first argument of ‘get404’, namely ‘uid’
In the second argument of ‘($)’, namely ‘get404 uid’
使用keyToValues
獲取PersistValue
值的列表。
keyToValues :: Key record -> [PersistValue]
例如,如果您知道鍵是一個Text值,那么您的列表將包含一個PersistText
值,您可以像這樣進行操作:
do uid <- lookupSession "_ID"
let pvals = keyToValues uid
[ PersistText txt ] = pvals
liftIO $ print pvals -- to see what pvals is
-- now txt is a Text value
...
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