Thursday, March 14, 2013

cdk and grails, why don't they get along...

so apperently the cdk depends on some xml libaries, which causes us all kind of error messages like this in grails:

| Loading Grails 2.1.0
| Configuring classpath
| Error Error executing script Help: loader constraint violation: when resolving overridden method "$RootHandler.setDocumentLocator(Lorg/xml/sax/Locator;)V" the class loader (instance of org/codehaus/groovy/grails/cli/support/GrailsRootLoader) of the current class, org/apache/tools/ant/helper/ProjectHelper2$RootHandler, and its superclass loader (instance of ), have different Class objects for the type org/xml/sax/Locator used in the signature (Use --stacktrace to see the full trace)

IDEA hook: Grails not found!
| Error java.lang.NullPointerException
| Error  at org.jetbrains.groovy.grails.rt.Agent$
| Error  at

which are rather annoying since all the mailing list say, to just run the dependency report to see what causes this problem. Great idea exact that grails crashes before it can generate the report...

So after a while of searching and goggling and shouting random words at my imac, I found an ugly solution which works rather well for now.
Basically make your BuildConfig.groovy file look like this and it should fix your current issues...
    dependencies {
        runtime 'postgresql:postgresql:8.2-504.jdbc3'


        compile('org.openscience.cdk:cdk-fingerprint:1.4.16') {
            transitive = false
        compile('org.openscience.cdk:cdk-inchi:1.4.16') {
            transitive = false
        compile('org.openscience.cdk:cdk-smarts:1.4.16')  {
            transitive = false
        compile('org.openscience.cdk:cdk-extra:1.4.16')  {
            transitive = false
        compile('org.openscience.cdk:cdk-dict:1.4.16')  {
            transitive = false
        compile('jama:jama:1.0.2')  {
            transitive = false
Maybe this help someone, who has the same issues with old XML-Apis and Xerces and so

Monday, March 11, 2013

Lift - getting access to a database

Since I recently started to play more and more with lift. I discovered that it's not always as easy as you think it is and once you find a solution it was easy indeed.

For example I want to connect to my database server, but have no desire to actually use any form of OR mapping.

So after googleing a bit and woundering how todo this. It's all rather simple.

In your Boot.scala file

def boot {
    // where to search snippet

    // Build SiteMap

    //rest based stuff

     * connection url for lift
    val vendor = new StandardDBVendor("org.postgresql.Driver","jdbc:postgresql://****/****",Full("username"),Full("password")) with ProtoDBVendor{
      override def maxPoolSize = 100
      override def doNotExpandBeyond = 200
    DB.defineConnectionManager(DefaultConnectionIdentifier, vendor)


This basically defines what to connect to and a connection pool with a max of 100 connections.

To actually access this connection and todo something with it, well this is remarkable easy.

          DB.performQuery("select * from data")