Groovy: More elegant way to achieve this? - groovy

Question

I have following groovy function:
def getDependantLibs(updatedLib) {
def dependants = []
getAllLibs().each { lib ->
try {
def ref = getFromStash("/repos/${lib}/dependencies.json").find { it.name == updatedLib }
if (ref != null) {
dependants.add([ name: lib, version: ref.version ])
}
} catch (err) {}
}
return dependants
}
My question is, can I achieve this in a more elegant way (maybe with groovy Collecion functions like collect, flatten, ...)

Answer 1

Yes, you can use collectMany. E.g.:
def deps = [1,2,3,4]
println deps.collectMany{
try {
if (it&1) {
throw new RuntimeException(it.toString())
}
(0..it).collect{
[x: it]
}
}
catch (Exception e) {
println "failed: $e.message"
return []
}
}
// output:
// failed: 1
// failed: 3
// [[x:0], [x:1], [x:2], [x:0], [x:1], [x:2], [x:3], [x:4]]

Answer 2

Instead of using Collection.each(Closure closure) you can utilize Collection.collect(Closure transform) for transforming each element of the list from one format to another and Collection.findAll(Closure predicate) to filter null elements from final list. Something like this:
def getDependantLibs(updatedLib) {
return getAllLibs().collect { lib ->
try {
[lib: lib, ref: getFromStash("/repos/${lib}/dependencies.json").find { it.name == updatedLib }]
} catch (err) {
[lib: lib, ref: null]
}
}.findAll { it.ref != null }.collect { [name: it.lib, version: it.ref.version] }
}
Using Java 8 Stream API
You can always use Java 8 Stream API with Groovy. The main advantage of using Stream API in this case is that all operations on stream are lazy - they are executed when reduction function is called. It means that you can apply n-number of transformations and only one iteration will be triggered. In Groovy if you apply let's say 3 bulk collection methods, Groovy will iterate 3 times.
Below you can find an example of using Java 8 Stream API in Groovy:
def getDependantLibsWithStream(updatedLib) {
return getAllLibs().stream()
.map({ lib ->
try {
[lib: lib, ref: getFromStash("/repos/${lib}/dependencies.json").find { it.name == updatedLib }]
} catch (err) {
[lib: lib, ref: null]
}
})
.filter({ it.ref != null })
.map({ [name: it.lib, version: it.ref.version] })
.collect(Collectors.toList())
}
I hope it helps.