Scala內存數據庫SQLite沒有這樣的表

使用Scala 2.10.2和Slick 2.1.0，我正在爲SQLite數據庫編寫一個包裝器。對於測試，我希望能夠創建一個內存數據庫，使用我的表填充它，插入一些數據，然後運行測試查詢。玩具相當於我的數據庫在下面的工作代碼段概述：Scala內存數據庫SQLite沒有這樣的表

import org.sqlite.JDBC 
import scala.slick.driver.SQLiteDriver.simple._ 

object MyDB 
{ 
    def testMemory() : Unit = MyDB.withMemoryTestDatabase(test) 

    def testFile() : Unit = MyDB.withFileTestDatabase(test) 

    val test : (MyDB) => Unit = 
    { 
     (mydb) => mydb.database.withSession{ implicit session => { 
      mydb.metadata.map(m => (m.key, m.value)).insert(("foo", "bar")) 
      assert(mydb.metadata("foo") == "bar") 
     } } 
    } 

    def withMemoryTestDatabase(testFunction : (MyDB) => Unit) : Unit = 
    { 
     val backend = new MyDB(Database.forURL("jdbc:sqlite::memory:", driver = "org.sqlite.JDBC")) 

     runTest(backend, testFunction) 
    } 

    def withFileTestDatabase(testFunction : (MyDB) => Unit) : Unit = 
    { 
     val backend = new MyDB(Database.forURL("jdbc:sqlite:test.sqlite", driver = "org.sqlite.JDBC")) 

     runTest(backend, testFunction) 

     val dbPath = new java.io.File("test.sqlite") 
     dbPath.delete 
    } 

    def runTest(backend : MyDB, testFunction : (MyDB) => Unit) : Unit = 
    { 
     backend.database.withSession{ implicit session => backend.metadata.ddl.create } 

     testFunction(backend) 
    } 
} 

class MyDB(val database : slick.driver.SQLiteDriver.backend.DatabaseDef) 
{ 
    class Metadata(tag : Tag) extends Table[(String,String)](tag, "Metadata") 
    { 
     def key = column[String]("key") 
     def value = column[String]("value") 

     def * = (key, value) 
    } 

    object metadata extends TableQuery(new Metadata(_)) 
    { 
     def apply(key : String) : String = database.withSession { implicit session => this.map(m => (m.key, m.value)).run.toMap.apply(key) } 
    }  
}

我現在遇到的問題是，與該代碼，MyDB.testFile()運行完美。但是，MyDB.testMemory()失敗，說元數據表不存在。完整的錯誤和追溯在這裏：

scala> MyDB.testFile 

scala> MyDB.testMemory 
java.sql.SQLException: [SQLITE_ERROR] SQL error or missing database (no such table: Metadata) 
    at org.sqlite.DB.newSQLException(DB.java:383) 
    at org.sqlite.DB.newSQLException(DB.java:387) 
    at org.sqlite.DB.throwex(DB.java:374) 
    at org.sqlite.NativeDB.prepare(Native Method) 
    at org.sqlite.DB.prepare(DB.java:123) 
    at org.sqlite.PrepStmt.<init>(PrepStmt.java:42) 
    at org.sqlite.Conn.prepareStatement(Conn.java:404) 
    at org.sqlite.Conn.prepareStatement(Conn.java:399) 
    at scala.slick.jdbc.JdbcBackend$SessionDef$class.prepareStatement(JdbcBackend.scala:152) 
    at scala.slick.jdbc.JdbcBackend$BaseSession.prepareStatement(JdbcBackend.scala:389) 
    at scala.slick.jdbc.JdbcBackend$SessionDef$class.withPreparedStatement(JdbcBackend.scala:190) 
    at scala.slick.jdbc.JdbcBackend$BaseSession.withPreparedStatement(JdbcBackend.scala:389) 
    at scala.slick.driver.JdbcInsertInvokerComponent$BaseInsertInvoker.preparedInsert(JdbcInsertInvokerComponent.scala:170) 
    at scala.slick.driver.JdbcInsertInvokerComponent$BaseInsertInvoker.internalInsert(JdbcInsertInvokerComponent.scala:180) 
    at scala.slick.driver.JdbcInsertInvokerComponent$BaseInsertInvoker.insert(JdbcInsertInvokerComponent.scala:175) 
    at MyDB$$anonfun$testMemory$1$$anonfun$apply$1.apply(MyDb.scala:9) 
    at MyDB$$anonfun$testMemory$1$$anonfun$apply$1.apply(MyDb.scala:8) 
    at scala.slick.backend.DatabaseComponent$DatabaseDef$class.withSession(DatabaseComponent.scala:34) 
    at scala.slick.jdbc.JdbcBackend$DatabaseFactoryDef$$anon$4.withSession(JdbcBackend.scala:61) 
    at MyDB$$anonfun$testMemory$1.apply(MyDb.scala:8) 
    at MyDB$$anonfun$testMemory$1.apply(MyDb.scala:8) 
    at MyDB$.withMemoryTestDatabase(MyDb.scala:28) 
    at MyDB$.testMemory(MyDb.scala:8) 
    at .<init>(<console>:8) 
    at .<clinit>(<console>) 
    at .<init>(<console>:7) 
    at .<clinit>(<console>) 
    at $print(<console>) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:606) 
    at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:734) 
    at scala.tools.nsc.interpreter.IMain$Request.loadAndRun(IMain.scala:983) 
    at scala.tools.nsc.interpreter.IMain.loadAndRunReq$1(IMain.scala:573) 
    at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:604) 
    at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:568) 
    at scala.tools.nsc.interpreter.ILoop.reallyInterpret$1(ILoop.scala:745) 
    at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:790) 
    at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:702) 
    at scala.tools.nsc.interpreter.ILoop.processLine$1(ILoop.scala:566) 
    at scala.tools.nsc.interpreter.ILoop.innerLoop$1(ILoop.scala:573) 
    at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:576) 
    at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply$mcZ$sp(ILoop.scala:867) 
    at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822) 
    at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822) 
    at scala.tools.nsc.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:135) 
    at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:822) 
    at scala.tools.nsc.interpreter.ILoop.main(ILoop.scala:889) 
    at xsbt.ConsoleInterface.run(ConsoleInterface.scala:69) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:606) 
    at sbt.compiler.AnalyzingCompiler.call(AnalyzingCompiler.scala:102) 
    at sbt.compiler.AnalyzingCompiler.console(AnalyzingCompiler.scala:77) 
    at sbt.Console.sbt$Console$$console0$1(Console.scala:23) 
    at sbt.Console$$anonfun$apply$2$$anonfun$apply$1.apply$mcV$sp(Console.scala:24) 
    at sbt.TrapExit$.sbt$TrapExit$$executeMain$1(TrapExit.scala:33) 
    at sbt.TrapExit$$anon$1.run(TrapExit.scala:42)

任何人都可以告訴我我哪裏會出錯嗎？

N.B. JDBC構造函數的參數:memory:似乎工作;它當然不會創建一個:memory:文件。

來源

2014-09-24 paulmdavies

我不確定，但是如果你與db建立多個連接，那麼數據不會持久。請參閱此處：http://www.sqlite.org/inmemorydb.html。您可能需要在jdbc uri的末尾添加咒語'？cache = shared'。 – 2014-09-24 16:21:15

聽起來似乎是合理的，但是一個名爲'jdbc：sqlite :: memory：？cache = shared'的URL創建一個名爲'：memory：？cache = shared'的文件，所以這不太合適。 – paulmdavies 2014-09-24 16:31:00

如果您使用的是用於sqlite jdbc的xerial庫，這可能有所幫助：https://groups.google.com/forum/#!topic/xerial/gGeqCw3KzvU – 2014-09-24 17:03:18

儘量保持連接打開（這有助於在H2，只有猜測的SQLite）：

def runTest(backend : MyDB, testFunction : (MyDB) => Unit) : Unit = 
{ 
    backend.database.withSession{ implicit session => 
     backend.metadata.ddl.create 
     testFunction(backend) 
    } 
}

來源

2014-09-24 23:39:05 cvogt

我修改了我的代碼，像這樣工作（我打算首先這樣做）。然後，我將'session'明確地傳遞給'testFunction'，並在測試函數中的每個數據庫調用中明確使用它。但是，這仍然行不通。調試打印確認創建並且測試正在使用相同的會話。我很茫然！ – paulmdavies 2014-09-25 08:49:55

可能會設置一個示例github項目來顯示效果 – cvogt 2014-10-02 23:09:54

這裏試試這個選項：How should one configure Slick to persist tables between sessions?

TLDR版本：添加「; DB_CLOSE_DELAY = -1」到你的數據庫網址的末尾。

來源

2014-12-19 10:14:41

Scala內存數據庫SQLite沒有這樣的表

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