Exception accessing Spring managed bean from Groovy closure - spring

Question

I have a simple Spring Boot application with 2 bean classes, a main class and a configuration class. Whenever I try to access the Spring managed Bank bean from a Groovy closure, I get an exception:
Exception in thread "main" java.lang.IllegalStateException: Failed to execute CommandLineRunner
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callGroovyObjectGetProperty(AbstractCallSite.java:304)
at org.springframework.boot.SpringApplication.runCommandLineRunners(SpringApplication.java:675)
at com.example.closures.ClosuresApplication$_run_closure1.doCall(ClosuresApplication.groovy:22)
at org.springframework.boot.SpringApplication.afterRefresh(SpringApplication.java:690)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:321)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:957)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:946)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.springframework.boot.SpringApplication$run.call(Unknown Source)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:45)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:324)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:110)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:130)
at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:292)
at com.example.closures.ClosuresApplication.main(ClosuresApplication.groovy:27)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1016)
Caused by: groovy.lang.MissingPropertyException: No such property: bank for class: com.example.closures.ClosuresApplication$$EnhancerBySpringCGLIB$$44735576
at groovy.lang.Closure.call(Closure.java:423)
at groovy.lang.Closure.call(Closure.java:439)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.each(DefaultGroovyMethods.java:2027)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:51)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.each(DefaultGroovyMethods.java:2012)
at org.codehaus.groovy.runtime.callsite.PogoGetPropertySite.getProperty(PogoGetPropertySite.java:49)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.each(DefaultGroovyMethods.java:2053)
at org.codehaus.groovy.runtime.dgm$162.invoke(Unknown Source)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callGroovyObjectGetProperty(AbstractCallSite.java:304)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoMetaMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:271)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:53)
at com.example.closures.ClosuresApplication$_run_closure1.doCall(ClosuresApplication.groovy:22)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:45)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:110)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:122)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.example.closures.ClosuresApplication.run(ClosuresApplication.groovy:21)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at org.springframework.boot.SpringApplication.runCommandLineRunners(SpringApplication.java:672)
... 9 common frames omitted
Bank.groovy
#Component
final class Bank {
final String name = 'MyBank'
final AutomatedTellerMachine insideAtm
final AutomatedTellerMachine outsideAtm
#Autowired
Bank(#Qualifier('insideAtm') final AutomatedTellerMachine insideAtm, #Qualifier('outsideAtm') final AutomatedTellerMachine outsideAtm) {
this.insideAtm = insideAtm
this.outsideAtm = outsideAtm
}
String getName() {
return name
}
AutomatedTellerMachine getInsideAtm() {
return insideAtm
}
AutomatedTellerMachine getOutsideAtm() {
return outsideAtm
}
}
AutomatedTellerMachine.groovy
final class AutomatedTellerMachine {
final String name
AutomatedTellerMachine(final String name) {
this.name = name
}
String getName() {
return name
}
}
AppConfig.groovy
#Configuration
class AppConfig {
#Bean(name = 'insideAtm')
AutomatedTellerMachine getInsideAtm() {
new AutomatedTellerMachine('insideAtm')
}
#Bean(name = 'outsideAtm')
AutomatedTellerMachine getOutsideAtm() {
new AutomatedTellerMachine('outsideAtm')
}
}
ClosuresApplication.groovy
#SpringBootApplication
class ClosuresApplication implements CommandLineRunner {
#Autowired
private Bank bank
#Override
void run(String... args) throws Exception {
for (def i = 0; i < 10; i++) {
printf 'Bank %02d: %s%n', (i + 1), bank
}
(1..10).each {
printf 'Bank %02d: %s%n', it, bank
}
}
static void main(String[] args) {
SpringApplication.run ClosuresApplication, args
}
}
The regular for loop works just fine, but the .each {} closure from Groovy gives an exception. Any ideas?

Answer 1

I have run into this problem at odd times and found that a simple work-around can fix it - add a reference to your bank variable in the run method:
def _bank = bank
(1..10).each {
printf 'Bank %02d: %s%n', it, _bank
}
It seems to be an odd scoping issue that I have never been able to determine the real cause of.

Answer 2

Another possible solution is converting bank field to groovy property by removing 'private' modifier.
#Autowired
Bank bank
This is slightly less visually hideous (especially if you having this issue with more than one field), but it does change access level of that field.
I've encountered a number of these issues, all seemingly related to using private fields inside various closures in spring-managed beans, specifically when the beans are 'enhanced' (proxied) by spring (EnhancerBySpringCGLIB).