How to use MySQL JDBC driver in an SBT Scala project?

Question

When I run my project for the first time during an SBT session, it throws the following exception when trying to access to a MySQL database:

java.lang.NoClassDefFoundError: scala/Ordered

When I run it again (and any time after it, during the same SBT session), it throws a different one:

java.sql.SQLException: No suitable driver found for jdbc:mysql://localhost/...

When I was using NetBeans, the same code was working Ok. Now, As I use SBT for building and Kate to edit and manage my project manually, I get these runtime errors.

MySQL JDBC driver (downloaded right from MySQL.com) JAR is in project's lib directory and all the other libraries I've put there work ok.

Here is the code:

import java.sql._ ... // read val dbc : Connection = DriverManager.getConnection("jdbc:mysql://localhost/...") val st : Statement = dbc.createStatement val rs : ResultSet = st.executeQuery("SELECT ...") if(rs.first) result = rs.getDouble("field") dbc.close ... // write val dbc : Connection = DriverManager.getConnection("jdbc:mysql://localhost/...") val st : Statement = dbc.createStatement st.execute("UPDATE ...") dbc.close 

I've seen a question that looks pretty related, but still no answer.

Answer 1

In the SBT project class there should be a line:

 // Declare MySQL connector Dependency   val mysql = "mysql" % "mysql-connector-java" % "5.1.12" 

This will import the JDBC driver JAR file for MySQL.

Did you load the driver? If you use this Util class to fetch the connections, the driver will be loaded exactly one time:

// Util Class object DaoUtil {   import java.sql.{DriverManager, Connection}    private var driverLoaded = false    private def loadDriver()  {     try{       Class.forName("com.mysql.jdbc.Driver").newInstance       driverLoaded = true     }catch{       case e: Exception  => {         println("ERROR: Driver not available: " + e.getMessage)         throw e       }     }   }    def getConnection(dbc: DbConnection): Connection =  {     // Only load driver first time     this.synchronized {       if(! driverLoaded) loadDriver()     }      // Get the connection     try{       DriverManager.getConnection(dbc.getConnectionString)     }catch{       case e: Exception  => {         println("ERROR: No connection: " + e.getMessage)         throw e       }     }   } } 

The code is taken from a simple SBT - MySQL tutorial I wrote some time ago. If you want to download the complete tutorial, see http://github.com/ollekullberg/SimpleOrder

Answer 2

In the project/plugins.sbt file add a line

libraryDependencies += "mysql" % "mysql-connector-java" % "5.1.12" 

Then if your in the sbt shell, restart it.