Question

我正在尝试在Yesod书中运行Persistent示例（第10章）。我在.hs文件中输入了初始示例，创建了一个cabal文件，并尝试编译。编译器抱怨它无法找到“持久”。我假设函数persist已经转移到一个新的包（我没有包括）或已被弃用，但我不知道哪个和hoogle没有阐明这个问题。任何帮助将非常感激。也许我应该回到本书所依据的Yesod版本。我应该安装哪个yesod平台？谢谢，蒂姆

以下是错误消息：

perry$ cabal install
Resolving dependencies...
Configuring chapter10-0.1.0.0...
Building chapter10-0.1.0.0...
Preprocessing executable 'chapter10' for chapter10-0.1.0.0...
[1 of 1] Compiling Main             ( ex1.hs, dist/build/chapter10/chapter10-tmp/Main.o )

ex1.hs:8:55: Not in scope: `persist'
cabal: Error: some packages failed to install:
chapter10-0.1.0.0 failed during the building phase. The exception was:
ExitFailure 1

这是我的chapter10.cabal文件：

-- Initial chapter10.cabal generated by cabal init.  For further 
-- documentation, see http://haskell.org/cabal/users-guide/
name:                chapter10
version:             0.1.0.0
license-file:        LICENSE
cabal-version:       >=1.8
build-type:          Simple

executable chapter10
  main-is:             ex1.hs
  -- other-modules:       
  build-depends:       base ==4.5.*
                       , yesod-platform
                       , yesod
                       , persistent-sqlite
                       , transformers
                       , persistent-template
                       , persistent

这是我的ex1.hs文件：

{-# LANGUAGE QuasiQuotes, TemplateHaskell, TypeFamilies, OverloadedStrings #-}
{-# LANGUAGE GADTs, FlexibleContexts #-}
import Database.Persist
import Database.Persist.Sqlite
import Database.Persist.TH
import Control.Monad.IO.Class (liftIO)

share [mkPersist sqlSettings, mkMigrate "migrateAll"] [persist|
Person
    name String
    age Int Maybe
    deriving Show
BlogPost
    title String
    authorId PersonId
    deriving Show
|]

main :: IO ()
main = withSqliteConn ":memory:" $ runSqlConn $ do
    runMigration migrateAll

    johnId <- insert $ Person "John Doe" $ Just 35
    janeId <- insert $ Person "Jane Doe" Nothing

    insert $ BlogPost "My fr1st p0st" johnId
    insert $ BlogPost "One more for good measure" johnId

    oneJohnPost <- selectList [BlogPostAuthorId ==. johnId] [LimitTo 1]
    liftIO $ print (oneJohnPost :: [Entity BlogPost])

    john <- get johnId
    liftIO $ print (john :: Maybe Person)

    delete janeId
    deleteWhere [BlogPostAuthorId ==. johnId]

以下是我的yesod和persistent包的版本：

perry$ ghc-pkg list| grep -i -e yesod -e persist
    persistent-1.2.0.1
    persistent-sqlite-1.2.0
    persistent-template-1.2.0.1
    yesod-1.2.1
    yesod-auth-1.2.0.1
    yesod-core-1.2.2
    yesod-form-1.3.0
    yesod-persistent-1.2.1
    yesod-platform-1.2.1
    yesod-routes-1.2.0.1
    yesod-static-1.2.0
    yesod-test-1.2.0

Answer 1

根据some older documentation，persist已被弃用。它似乎已在版本1.2.0中删除。

persist :: QuasiQuoter

不推荐使用：请改用persistUpperCase。

Yesod书中的第一个持久性示例将无法编译 - 无法找到持久性

1 个答案: