Groovy Map Issue with Variable Properties and String INterpolation

Question

I have been navigating map structures fine for a long time now. Yet, for some reason, the root of this problem escapes me. I've tried bracket notation as well, no luck.

Why doesn't the final output (null) return "[serverinfo:[listenPort:19001]]"

If I replace the two instances of ' "$instanceName" ' with simply ' services ', it works.

String instanceName = "Services"
Map serverNode = [
    instances:[
        "$instanceName":[
            serverinfo:[
                listenPort:19001
            ]
        ]
    ]
]

println "$instanceName"
println serverNode.instances
println serverNode.instances."$instanceName"

//output 
Services
[Services:[serverinfo:[listenPort:19001]]]
null

Jérémie B · Accepted Answer · 2016-02-19 15:22:19Z

3

The type of "$instanceName" is GStringImpl, not String. It's a common mistake (and hard to find!)

def serverNode = [
    instances:[
        ("$instanceName" as String):[
            serverinfo:[
                listenPort:19001
            ]
        ]
    ]
]

as stated by @tim_yates in comment, if your interpolated string is as simple as in this example (ie ,"${property}"), then you can use the (property) syntax : Groovy put the value of the property as a key, not the word "property"

edited Feb 19, 2016 at 15:22

answered Feb 19, 2016 at 14:32

Jérémie B

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4 Comments

tim_yates Over a year ago

Or (instanceName):[

Jérémie B Over a year ago

yes you're right, and it's much better than my answer :-) I was answering more strictly as this question about gstring in map (but the result is..ugly)

tim_yates Over a year ago

Completely agree, and they do mention interpolation, so I'm guessing their actual code is more complex ;-)

solvingJ Over a year ago

Thank you so much, this significantly improved my ability to work with maps, and answered a particularly frustrating little detail.

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