CODEWITHSUNDEEP
jsongrailsgroovy
Mickey Ristroph
Mickey Ristroph

Reputation: 601

Types of dynamic types in Groovy

Main question: What operators, properties, etc. can be used to determine the type of variables in Groovy?

Background:

I have an arbitrarily deeply-nested dictionary data structure. It is the result of calling request.JSON in a Grails controller. I would first like to verify certain keys are in the dictionary, with the appropriate types. The way I would like to implement this is by creating a prototypical data structure and defining a method to compare data structures. Something like:

def prototype = [ username: "JennyJeans",
                   message: [ subject: "Hello World!",
                                 body: "Will write soon."
                            ]
                 ]

Of course, the content of the Strings here doesn't matter. Then, in my actions, I validate like this:

if(similarDataStructure(prototype, request.JSON)) {
// XXX
} else {
 // report error
}

So, what does the similarDataStructure method do? In pseudocode:

def similarDataStructure(a, b) {
  if(type(a) != type(b)) return false

  if(type(a) == dictionary) {
    for key in a:
      if(!similarDataStructure(a[key], b[key])) return false
  }

  return true
}

If you can think of a better way to do deep validation, let me know.

Upvotes: 1

Views: 1370

Answers (1)

chanwit
chanwit

Reputation: 3214

To obtain types, you can use a.class, b.class and compare them: if(a.class == b.class) { }

To check if it's a dictionary, you can call: a instanceof Map.

However, try the following code in Groovy console to see it yourself ;-)

def src = [ username: "JennyJeans",
           message: [ subject: "Hello World!",
                      body: "Will write soon."]
         ]

def p1 = [ username: "JennyJeans",
           message: [ subject: "Hello World!",
                      body: "Will write soon."]
         ]

def p2 = [ username: "JennyJeans",
           message: [ subject: "Hello World!",
                      body: "Will read soon."]
         ]

println src == p1
println src == p2

Upvotes: 1

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