带有 MySQL 的 Slick 2.0 的“Hello World”示例答案

【问题标题】："Hello World" example for Slick 2.0 with MySQL带有 MySQL 的 Slick 2.0 的“Hello World”示例
【发布时间】：2014-05-02 19:24:41
【问题描述】：

是否有示例说明如何使用 Scala 的 Slick 2.0.1 库连接到 MySQL 数据库？我无法通过谷歌搜索找到最新的示例...

最近，我一直在考虑将我使用 PHP 开发的 Web 应用程序的代码移植到 Scala 中。我一直在寻找一种编程语言，它具有（i）一个拥有大量用户的 Web 应用程序框架，（ii）提供编译时错误检查，（iii）很好的测试工具等等......一些使用 Scala 和 Play 框架开发 Web 应用程序的案例研究（例如， huffpost 和 cousera），它开始对我很有吸引力，我决定试一试。

由于上一个项目的所有数据都保存在 MySQL 数据库中，因此我正在研究 Scala 为我的程序提供的连接 MySQL 的功能。我遇到了 Slick。我遵循 Typesafe Activator 中的 Hello-Slick example，它指导我如何使用内存数据库（即 h2），我喜欢它的语法和抽象级别。现在，我想将 Slick 与 MySQL 一起使用。我尝试更改导入语句

import scala.slick.driver.H2Driver.simple._

到

import scala.slick.driver.MySQLDriver.simple._

在上述示例中的HelloSlick.scala 和Tables.scala 中（请参阅下面代码的完整副本）。但是，我在编译时收到以下错误消息：

/Users/kotaro/Documents/Scala/hello-slick/src/test/scala/TablesSuite.scala

值 ddl 不是 scala.slick.lifted.TableQuery[Suppliers] 的成员

def createSchema() = (suppliers.ddl ++ coffees.ddl).create
                              ^

有人知道这是什么原因吗？根据这篇文章（slick exception when trying to connect to MySql），尽管我收到的错误消息不同，但我可能会缺少添加一些依赖项。如果有一个很好的例子可以让我掌握如何将 Slick 与 MySQL 一起使用，那也会有很大帮助。

我在 XAMPP 1.7.3 中使用 Scala 2.10.3、MySQL 以及 OS X 10.8 和 JRE 1.6。

非常感谢您提前提供的帮助！

以下是代码的完整副本。

HelloSlick.scala

import scala.slick.driver.MySQLDriver.simple._
//import scala.slick.driver.H2Driver.simple._

// The main application
object HelloSlick extends App {

  // The query interface for the Suppliers table
  val suppliers: TableQuery[Suppliers] = TableQuery[Suppliers]

  // the query interface for the Coffees table
  val coffees: TableQuery[Coffees] = TableQuery[Coffees]

  // Create a connection (called a "session") to an in-memory H2 database
  Database.forURL("jdbc:mysql://localhost:3306/test", driver="com.mysql.jdbc.Driver", user="root", password="").withSession { implicit session =>

  // Create the schema by combining the DDLs for the Suppliers and Coffees tables using the query interfaces
    (suppliers.ddl ++ coffees.ddl).create


    /* Create / Insert */

    // Insert some suppliers
    suppliers += (101, "Acme, Inc.", "99 Market Street", "Groundsville", "CA", "95199")
    suppliers += (49, "Superior Coffee", "1 Party Place", "Mendocino", "CA", "95460")
    suppliers += (150, "The High Ground", "100 Coffee Lane", "Meadows", "CA", "93966")

    // Insert some coffees (using JDBC's batch insert feature)
    val coffeesInsertResult: Option[Int] = coffees ++= Seq (
      ("Colombian",         101, 7.99, 0, 0),
      ("French_Roast",       49, 8.99, 0, 0),
      ("Espresso",          150, 9.99, 0, 0),
      ("Colombian_Decaf",   101, 8.99, 0, 0),
      ("French_Roast_Decaf", 49, 9.99, 0, 0)
    )

    val allSuppliers: List[(Int, String, String, String, String, String)] = suppliers.list

    // Print the number of rows inserted
    coffeesInsertResult foreach (numRows => println(s"Inserted $numRows rows into the Coffees table"))


    /* Read / Query / Select */

    // Print the SQL for the Coffees query
    println("Generated SQL for base Coffees query:\n" + coffees.selectStatement)

    // Query the Coffees table using a foreach and print each row
    coffees foreach { case (name, supID, price, sales, total) =>
      println("  " + name + "\t" + supID + "\t" + price + "\t" + sales + "\t" + total)
    }


    /* Filtering / Where */

    // Construct a query where the price of Coffees is > 9.0
    val filterQuery: Query[Coffees, (String, Int, Double, Int, Int)] = coffees.filter(_.price > 9.0)

    println("Generated SQL for filter query:\n" + filterQuery.selectStatement)

    // Execute the query
    println(filterQuery.list)


    /* Update */

    // Construct an update query with the sales column being the one to update
    val updateQuery: Query[Column[Int], Int] = coffees.map(_.sales)

    // Print the SQL for the Coffees update query
    println("Generated SQL for Coffees update:\n" + updateQuery.updateStatement)

    // Perform the update
    val numUpdatedRows = updateQuery.update(1)

    println(s"Updated $numUpdatedRows rows")


    /* Delete */

    // Construct a delete query that deletes coffees with a price less than 8.0
    val deleteQuery: Query[Coffees,(String, Int, Double, Int, Int)] = coffees.filter(_.price < 8.0)

    // Print the SQL for the Coffees delete query
    println("Generated SQL for Coffees delete:\n" + deleteQuery.deleteStatement)

    // Perform the delete
    val numDeletedRows = deleteQuery.delete

    println(s"Deleted $numDeletedRows rows")


    /* Selecting Specific Columns */

    // Construct a new coffees query that just selects the name
    val justNameQuery: Query[Column[String], String] = coffees.map(_.name)

    println("Generated SQL for query returning just the name:\n" + justNameQuery.selectStatement)

    // Execute the query
    println(justNameQuery.list)


    /* Sorting / Order By */

    val sortByPriceQuery: Query[Coffees, (String, Int, Double, Int, Int)] = coffees.sortBy(_.price)

    println("Generated SQL for query sorted by price:\n" + sortByPriceQuery.selectStatement)

    // Execute the query
    println(sortByPriceQuery.list)


    /* Query Composition */

    val composedQuery: Query[Column[String], String] = coffees.sortBy(_.name).take(3).filter(_.price > 9.0).map(_.name)

    println("Generated SQL for composed query:\n" + composedQuery.selectStatement)

    // Execute the composed query
    println(composedQuery.list)


    /* Joins */

    // Join the tables using the relationship defined in the Coffees table
    val joinQuery: Query[(Column[String], Column[String]), (String, String)] = for {
      c <- coffees if c.price > 9.0
      s <- c.supplier
    } yield (c.name, s.name)

    println("Generated SQL for the join query:\n" + joinQuery.selectStatement)

    // Print the rows which contain the coffee name and the supplier name
    println(joinQuery.list)


    /* Computed Values */

    // Create a new computed column that calculates the max price
    val maxPriceColumn: Column[Option[Double]] = coffees.map(_.price).max

    println("Generated SQL for max price column:\n" + maxPriceColumn.selectStatement)

    // Execute the computed value query
    println(maxPriceColumn.run)


    /* Manual SQL / String Interpolation */

    // Required import for the sql interpolator
    import scala.slick.jdbc.StaticQuery.interpolation

    // A value to insert into the statement
    val state = "CA"

    // Construct a SQL statement manually with an interpolated value
    val plainQuery = sql"select SUP_NAME from SUPPLIERS where STATE = $state".as[String]

    println("Generated SQL for plain query:\n" + plainQuery.getStatement)

    // Execute the query
    println(plainQuery.list)

  }
}

Tables.scala

import scala.slick.driver.MySQLDriver.simple._
import scala.slick.lifted.{ProvenShape, ForeignKeyQuery}


// A Suppliers table with 6 columns: id, name, street, city, state, zip
class Suppliers(tag: Tag) extends Table[(Int, String, String, String, String, String)](tag, "SUPPLIERS") {
  def id: Column[Int] = column[Int]("SUP_ID", O.PrimaryKey) // This is the primary key column
  def name: Column[String] = column[String]("SUP_NAME")
  def street: Column[String] = column[String]("STREET")
  def city: Column[String] = column[String]("CITY")
  def state: Column[String] = column[String]("STATE")
  def zip: Column[String] = column[String]("ZIP")
  
  // Every table needs a * projection with the same type as the table's type parameter
  def * : ProvenShape[(Int, String, String, String, String, String)] = (id, name, street, city, state, zip)
}

// A Coffees table with 5 columns: name, supplier id, price, sales, total
class Coffees(tag: Tag) extends Table[(String, Int, Double, Int, Int)](tag, "COFFEES") {
  def name: Column[String] = column[String]("COF_NAME", O.PrimaryKey)
  def supID: Column[Int] = column[Int]("SUP_ID")
  def price: Column[Double] = column[Double]("PRICE")
  def sales: Column[Int] = column[Int]("SALES")
  def total: Column[Int] = column[Int]("TOTAL")
  
  def * : ProvenShape[(String, Int, Double, Int, Int)] = (name, supID, price, sales, total)
  
  // A reified foreign key relation that can be navigated to create a join
  def supplier: ForeignKeyQuery[Suppliers, (Int, String, String, String, String, String)] = 
    foreignKey("SUP_FK", supID, TableQuery[Suppliers])(_.id)
}

【问题讨论】：

标签： mysql scala slick

【解决方案1】：

您可能忽略了错误消息是指“TableSuite.scala”

/Users/kotaro/Documents/Scala/hello-slick/src/test/scala/TablesSuite.scala

value ddl is not a member of scala.slick.lifted.TableQuery[Suppliers]

def createSchema() = (suppliers.ddl ++ coffees.ddl).create

您还需要在其中更改导入。

【讨论】：