Question

i have the following code for handling default values when a lookup returns null

def user = User.find('admin') 
    return user?.address?user:null 

this works as expected

however when using the Elvis operator like:

def user = User.find('admin') 
    return user?.address?:null 

i get an exception thrown:

org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object 'true'         with class 'java.lang.Boolean' to class 'com.code.User' 

I was expecting Elvis to behave exactly like the ternary operator….?

thanks!

Answer 1

This returns user if the user is not null and user.address evaluates to true:

return user?.address?user:null 

This returns user.address if the user is not null and user.address evaluates to true

return user?.address?:null 

I assume user.address is a boolean? So the second one is trying to return a boolean probably from a method you say returns a User in the definition