Check if a JSON is empty using Circe

Question

Does circe provide any function to check if an io.circe.Json object is empty?

The Json documentation doesn't report anything about it, while the JsonObject documentation talks about an isEmpty function, but I verified that

 {}.asJson.asObject.isEmpty // false

so it doesn't work as I expected.

Answer 1

It does not work in a way you expected, because Json.asObject returns Some in case if underlying JSON is object, because apart of that it also can either String, Number, Null or Array, hence "{}".asObject (not really correct just for sake of example) - returns Some(JsonObject()) and you receive false because Some.isEmpty=false. What you want is :

import io.circe._, io.circe.parser._
val emptyJsonObject = parse("{}").toOption.get //Unsafe operation for sake of answer example - DO NOT do it in production code.
println(emptyJsonObject.asObject) // prints `Some(object[])`
println(emptyJsonObject.asObject.exists(_.nonEmpty)) //prints `false`

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