How to change method name and argument list at Runtime Dynamically
Posted By : Ankush Kocher | 18-Nov-2014
In this blog we will see how to call a method and change the method name dynamically or can invoke a method even if we don't know the method name until it is invoked.
Consider, we have a domain class user which has fields username and we want to fetch an object from database, accordingly what we have name or id of user .
Domain class
class User{
String username
static constraints = {
username nullable: true
}
}
and in Controller......
class UserController{
def action(){
def mathodName = ""
if(params.value.getClass() = "String"){
mathodName = "findByUsername"
}
else{
mathodName = "get"
}
def user = User.${mathodName}(value)
[user:user]
}
}
So,we can change method name at runTime
and we can also "spread" the arguments in a method call, when we have a list of arguments :
e.g.
def maximum(int i1, int i2) {
Math.max(i1, i2)
}
def numbers = [1, 2]
maximum( *numbers ) == 2
This also works in combination of the invocation with a GString:
someObject."$methodName"(*args)
This is a simple example same can be achived by just calling method in condition but this can be more useful in some cases.
Thanks
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About Author
Ankush Kocher
Ankush is a bright web app developer with expertise in Groovy and Grails development. Ankush is also an expert AngularJS developer.