Special upgrade notes for Grails 1.3.x to 2.2.x

Usually there are quite extensive upgrade notes that should take you from one Grails release to another. Every now and then there are subtle changes in behaviour that may break your application without being mentioned in the notes. We are maintaining some Grails applications started years ago in the Grails 1.0.x era and a bucket full of experience upgrading between major releases.

Here are our special upgrade notes for 1.3.x to 2.2.x:

• domain constructors with default parameters lead to DuplicateMethodErrors. The easy fix is to change code like

  public MyDomain(def number = 0) {
      ...
  }
  

  to

  public MyDomain() {
      this(0)
  }
  
  public MyDomain(def number) {
      ...
  }
  

• private static classes are disallowed in controllers. So in general avoid visibility modifiers for multiple classes in one file.
• If you use Apache Shiro with the Grails Shiro Plugin for authentication, you will have to do some work for existing accounts to stay working because the default CredentialMatcher changed from SHA1 to SHA256. To get the old behaviour add the following to conf/spring/resources.groovy:

  import org.apache.shiro.authc.credential.Sha1CredentialsMatcher
  
  beans = {
      ...
      credentialMatcher(Sha1CredentialsMatcher) {
          storedCredentialsHexEncoded = true
      }
      ...
  }
  
  

• A domain class property or even a domain class with the name “environment” clashes(d) with a spring bean (GRAILS-7851) and leads to unexpected effects. Renaming the property or class is a viable workaround.
• Namespacing in tag libs is broken so that you cannot name a local variable “properties”:

      def myTag = { attrs, body ->
          String properties = 'some string'
  

  leads to a bogus error
  [groovyc] TagLib.groovy: -1: The return type of java.lang.String getProperties() in TagLib$_closure24_closure87 is incompatible with java.util.Map getProperties() in groovy.lang.Closure.Simply renaming the variable to something like props fixes the problem.

• Migrations need package statements if you organize them in subdirectories.

In addition to the changes mentioned in the official release notes solving the issues above made our application work again with the latest and greatest Grails release.