I'm trying to mix-in a class in my Groovy/Grails app, and I'm using the syntax defined in the docs, but I keep getting an error.
I have a domain class that looks like this:
class Person {
mixin(ImagesMixin)
// ...
}
It compiles fine, but for some reason it won't work. The file containing ImagesMixin is located in my /src/groovy/
directory.
I've tried it using Groovy versions 1.5.7 and 1.6-RC1 without any luck. Does anyone know what I'm doing wrong?
stacktrace:
2008-12-30 17:58:25.258::WARN: Failed startup of context org.mortbay.jetty.webapp.WebAppContext@562791{/FinalTransmission,/home/kuccello/Development/workspaces/lifeforce/FinalTransmission/web-app}
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'pluginManager' defined in ServletContext resource [/WEB-INF/applicationContext.xml]: Invocation of init method failed; nested exception is java.lang.ExceptionInInitializerError
at java.security.AccessController.doPrivileged(Native Method)
at RunApp_groovy$_run_closure2_closure7.doCall(RunApp_groovy:67)
at RunApp_groovy$_run_closure2_closure7.doCall(RunApp_groovy)
at Init_groovy$_run_closure6.doCall(Init_groovy:131)
at RunApp_groovy$_run_closure2.doCall(RunApp_groovy:66)
at RunApp_groovy$_run_closure2.doCall(RunApp_groovy)
at RunApp_groovy$_run_closure1.doCall(RunApp_groovy:57)
at RunApp_groovy$_run_closure1.doCall(RunApp_groovy)
at gant.Gant.dispatch(Gant.groovy:271)
at gant.Gant.this$2$dispatch(Gant.groovy)
at gant.Gant.invokeMethod(Gant.groovy)
at gant.Gant.processTargets(Gant.groovy:436)
at gant.Gant.processArgs(Gant.groovy:372)
Caused by: java.lang.ExceptionInInitializerError
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:169)
at Episode.class$(Episode.groovy)
at Episode.<clinit>(Episode.groovy)
... 13 more
Caused by: groovy.lang.MissingMethodException: No signature of method: static Person.mixin() is applicable for argument types: (java.lang.Class) values: {class ImagesMixin}
at Broadcast.<clinit>(MyClass.groovy:17)
... 17 more
2008-12-30 17:58:25.259::WARN: Nested in org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'pluginManager' defined in ServletContext resource [/WEB-INF/applicationContext.xml]: Invocation of init method failed; nested exception is java.lang.ExceptionInInitializerError:
groovy.lang.MissingMethodException: No signature of method: Person.mixin() is applicable for argument types: (java.lang.Class) values: {class ImagesMixin}
at Broadcast.<clinit>(Person.groovy:17)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:169)
at Episode.class$(BelongsToMyClass.groovy)
at Episode.<clinit>(BelongsToMyClass.groovy)
at java.security.AccessController.doPrivileged(Native Method)
at RunApp_groovy$_run_closure2_closure7.doCall(RunApp_groovy:67)
at RunApp_groovy$_run_closure2_closure7.doCall(RunApp_groovy)
at Init_groovy$_run_closure6.doCall(Init_groovy:131)
at RunApp_groovy$_run_closure2.doCall(RunApp_groovy:66)
at RunApp_groovy$_run_closure2.doCall(RunApp_groovy)
at RunApp_groovy$_run_closure1.doCall(RunApp_groovy:57)
at RunApp_groovy$_run_closure1.doCall(RunApp_groovy)
at gant.Gant.dispatch(Gant.groovy:271)
at gant.Gant.this$2$dispatch(Gant.groovy)
at gant.Gant.invokeMethod(Gant.groovy)
at gant.Gant.processTargets(Gant.groovy:436)
at gant.Gant.processArgs(Gant.groovy:372)
2008-12-30 17:58:25.271::INFO: Started [email protected]:8080
Since Groovy 1.6 you can either apply a mixin at compile-time to a class using an annotation
@Mixin(ImagesMixin)
class Person {
}
Or you can apply the mixin at runtime like this:
def myMixin = ImagesMixin
Person.mixin myMixin
The latter approach is more dynamic as the class to mixin can be determined at runtime. Further information about Groovy mixins is available here.
In my experience, a lot of meta-programming of domain classes simply doesn't work. I don't exactly know why, but suspect it's due to the fact these classes are already very heavily meta-programmed by the Grails runtime. In general my approach is
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With