[Ramadda-users] Connecting to multiple database types

[Scott W. <sco...@un...>]

Hi Ramadda users,

We've been running into some trouble trying to create links to a MySQL database using the 'Database Table' type. From what I can tell Ramadda will only set up the JDBC driver when connecting to its main database, not for external tables. Since our Ramadda DB is using Postgres, only the Postgres driver is loaded and we get an error when setting up the Database Table:

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

The patch below changes the DB manager to load the driver both for the main database and external connections. Initial testing shows that this works, however I'm not familiar enough with server-side Java to know if loading the driver for every external connection would have a performance impact.

Is there a better way to handle connecting to multiple database types?

Cheers, Scott

--

Index: src/org/ramadda/repository/database/DatabaseManager.java
===================================================================
--- src/org/ramadda/repository/database/DatabaseManager.java	(revision 5793)
+++ src/org/ramadda/repository/database/DatabaseManager.java	(working copy)
@@ -362,7 +362,22 @@
              "Could not determine database type:" + jdbc);
      }
  
+    /**
+     * Load the JDBC driver for `dbType`
+     */
+    private void loadDriver(String dbType) {
+        String propertyName = PROP_DB_DRIVER.replace("${db}", dbType);
+        String className = (String) getRepository().getProperty(propertyName);
  
+        try {
+            Class.forName(className);
+        }
+        catch (ClassNotFoundException e) {
+            System.err.println("Could not find JDBC driver for "+dbType);
+        }
+    }
+
+
      /**
       * _more_
       *
@@ -378,14 +393,8 @@
                                            String userName, String password)
              throws Exception {
          String dbType = getDbType(connectionUrl);
-        String driverClassPropertyName = PROP_DB_DRIVER.replace("${db}",
-                                             dbType);
-        //      System.err.println("JDBC Property:" + driverClassPropertyName);
-        String driverClassName =
-            (String) getRepository().getProperty(driverClassPropertyName);
+        loadDriver(dbType);
  
-        Misc.findClass(driverClassName);
-
          BasicDataSource ds = new BasicDataSource();
  
  
@@ -404,7 +413,6 @@
          //        System.err.println("DatabaseManager.makeDataSource: url="  + connectionUrl);
          //        System.err.println("JDBC driver class:" + driverClassName + " db type:" + dbType);
  
-        ds.setDriverClassName(driverClassName);
          ds.setUsername(userName);
          ds.setPassword(password);
          ds.setUrl(connectionURL);
@@ -437,6 +445,10 @@
      public Connection getExternalConnection(String prefix) throws Exception {
          String connectionURL = getRepository().getProperty(prefix + ".url",
                                     (String) null);
+
+        String dbType = getDbType(connectionURL);
+        loadDriver(dbType);
+
          String user = getRepository().getProperty(prefix + ".user",
                            (String) null);
          String password = getRepository().getProperty(prefix + ".password",


-- 
Scott Wales, Computational Modelling Systems
ARC Centre of Excellence For Climate Systems Science
School of Earth Sciences, The University of Melbourne, Australia 3010
sco...@un... / P +61 3 8344 6907 / M 0450 012 907