Solution for array.length in JAVA

[backtrackshubham]

HI Team, thanks for creating a wonderful library, kudos to everyone in the team,

I am facing a problem, so I am using json-logic-java and on the online playground the following rule works fine,

data  => {arr: [1,2,3,4]}

rule => "{\"*\": [{\"var\": \"arr.length\"}, 5]}";

// output as 20

But when I am trying to use the same I java code it throws some error, like number format

// Below code fails
   JsonLogic jsonLogic = new JsonLogic();

// Set up some JSON and some data.
    String expression = "{\"*\": [{\"var\": \"arr.length\"}, 5]}";
    Map<String, Object> data = new HashMap<>();
    data.put("x", 10);
    data.put("arr", asList(1, 2, 3, 4, 5));

// Evaluate the result.
    double result = (double) jsonLogic.apply(expression, data);
    assert result == 20.0;
  }

I have made a workaround for this following the docs but I was wondering if there is a cleaner way to achieve the same, below is the work around

    JsonLogic jsonLogic = new JsonLogic();

// Set up some JSON and some data.
    String expression = "{\"*\": [{\"var\": \"arrLength\"}, 5]}";
    Map<String, Object> data = new HashMap<>();
    data.put("x", 10);
    data.put("arr", asList(1, 2, 3, 4, 5));
    List<Map<String, Object>> selectedItems = (List<Map<String, Object>>) data.get("arr");
   // Putting the value for size
    data.put("arrLength", selectedItems.size());

// Evaluate the result.
    double result = (double) jsonLogic.apply(expression, data);
    assert result == 25.0;
  }

[verhas]

JsonLogic can calculate the length of an array. You do not need to pass this value as a separate field:

Data:

{ "a" : [1,2,3,4,5] }

Rule:

{"reduce":[
    {"var":"a"},
    {"+":[1, {"var":"accumulator"}]},
    0
]}

[paninavika39]

try $.size()

[hekaifei]

@backtrackshubham
I also encountered the same problem and found that the author himself didn't implement it either. The page was hardcoded