应该如何配置Slick在会话之间持久化表？ [英] How should one configure Slick to persist tables between sessions?

问题描述

我在设置Slick 2.0.2时遇到了一些问题。在一个会话中执行的任何配置在下一个会话中丢失。例如，在第一个会话中，我创建表并添加三个人：

I have experienced some issues while setting up Slick 2.0.2. Any configuration that I do in one session is lost in the next. For example, in the first session, I create the table and add three people:

// H2 in-memory database
lazy val db = Database.forURL("jdbc:h2:mem:contacts", driver="org.h2.Driver")

// Contacts table
lazy val contacts = TableQuery[ContactsSchema]

// Initial session
db withSession { implicit session =>
  contacts.ddl.create

  // Inserts sample data
  contacts += Person("John", "123 Main street", 29)
  contacts += Person("Greg", "Neither here nor there", 40)
  contacts += Person("Michael", "Continental U.S.", 34)

  // Successfully retrieves data
  contacts foreach { person =>
    println(person)
  }
}

到这一点。输出重复我添加的三个人。当我开始一个新的会话，我开始遇到问题。

All is well up to this point. The output repeats the three people whom I added. When I start a new session, I start to experience issues.

// New session in which the previous data is lost
db withSession { implicit session =>
  contacts foreach { person =>
    println(person)
  }
}

创建一个 org.h2.jdbc.JdbcSQLException：表CONTACTS未找到异常。如果我编辑如下

The above block creates a org.h2.jdbc.JdbcSQLException: Table "CONTACTS" not found exception. If I edit as follows

db withSession { implicit session =>
  contacts.ddl.create
  contacts foreach { person =>
    println(person)
  }
}

数据已删除。

我看到 Slick的Scalatra指南使用类似于我的配置。我究竟做错了什么？如何让数据在会话之间保持？

I see that the Scalatra guide to Slick uses a similar configuration to mine. What am I doing wrong? How should I get the data to persist between sessions? Does the fact that I am using an in-memory database have anything to do with it?

推荐答案

有两个选择。

创建会话并保持打开。这可以通过调用堆栈或db.createSession上的withSession范围来实现。

Either create a session and keep it open. That can be done with a withSession scope lower on the call stack or db.createSession.

或者添加; DB_CLOSE_DELAY = -1 到数据库url。

Or add ;DB_CLOSE_DELAY=-1 to the database url. That keeps the db alive as long as the vm runs.

请参阅 http://www.h2database.com/html/features.html#in_memory_databases

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