Parsing nested collection in scala - json

Question

I have a collection structure as shown below. I need to build the statement based on k,v pairs in the map. The level of nesting is not known prior and code needs to parse it dynamically.
Structure:
case class Step(id: Option[String], stepId: Option[String], parameters: Option[Map[String, Any]])
val sample = Step(id = Some("a1"), Some("case"), Some(
Map(
"CONDITIONAL" -> List(
Map("comparison" -> List(
Map("comparision" -> List(
Map("comparision" -> List(
Map("comparator" -> List(
Map(
"EVAL" -> "c11",
"OPERATION" -> "equals to",
"WHEN" -> List("A")),
Map(
"eval" -> "c12",
"operation" -> "in",
"when" -> List("B")),
Map(
"eval" -> "c13",
"operation" -> "starts with",
"when" -> List("C")
)),
"operator" -> "OR"
),
Map("comparator" -> List(
Map(
"EVAL" -> "c21",
"OPERATION" -> "equals to",
"WHEN" -> List("A")),
Map(
"eval" -> "c22",
"operation" -> "in",
"when" -> List("B")
)),
"operator" -> "OR"
)),
"operator" -> "AND"
),
Map("comparator" -> List(
Map(
"EVAL" -> "c31",
"OPERATION" -> "equals to",
"WHEN" -> List("A")),
Map(
"EVAL" -> "c32",
"OPERATION" -> "in",
"WHEN" -> List("B")),
Map(
"EVAL" -> "c33",
"OPERATION" -> "starts with",
"WHEN" -> List("C")
)),
"operator" -> "OR"
)),
"operator" -> "OR"
)),
"THEN" -> "result"
)),
"ELSE" -> "default"
))
)
val stepsLower = sample.parameters.get.map(p => p._1.toLowerCase -> p._2)
val comparisons = stepsLower("conditional").asInstanceOf[List[Map[String, Any]]]
Now I need to parse data under the conditional (in comparisons) by evaluating the structure.
The result should be ((c11 OR c12 OR c13 ) AND (c21 OR c22)) OR (c31 OR c32 OR c33 OR c34)

Answer 1

Here is the code snippet that should work for all your use cases.
case class Step(id: Option[String], stepId: Option[String], parameters: Option[Map[String, Any]])
val sample1 = Step(id = Some("a1"), Some("case"), Some(Map(
"CONDITIONAL" -> List(
Map("comparison" -> List(
Map("comparison" -> List(
Map("comparison" -> List(
Map("comparator" -> List(
Map(
"eval" -> "c11",
"operation" -> "equals to",
"when" -> List("A")),
Map(
"eval" -> "c12",
"operation" -> "in",
"when" -> List("B")),
Map(
"eval" -> "c13",
"operation" -> "starts with",
"when" -> List("C")
)),
"operator" -> "OR"
),
Map("comparator" -> List(
Map(
"eval" -> "c21",
"operation" -> "equals to",
"when" -> List("A")),
Map(
"eval" -> "c22",
"operation" -> "in",
"when" -> List("B")
)),
"operator" -> "OR"
)),
"operator" -> "AND"
),
Map("comparator" -> List(
Map(
"eval" -> "c31",
"operation" -> "equals to",
"when" -> List("A")),
Map(
"eval" -> "c32",
"operation" -> "in",
"when" -> List("B")),
Map(
"eval" -> "c33",
"operation" -> "starts with",
"when" -> List("C")
)),
"operator" -> "OR"
)),
"operator" -> "OR"
)),
"then" -> "result"
)),
"else" -> "default"
))
)
val sample2 = Step(id = Some("a1"), Some("case"), Some(
Map(
"conditional" -> List(
Map("comparison" -> List(
Map("comparison" -> List(
Map("comparator" -> List(
Map(
"eval" -> "c11",
"operation" -> "equals to",
"when" -> List("A")),
Map(
"eval" -> "c12",
"operation" -> "in",
"when" -> List("B", "b"))),
"operator" -> "AND"),
Map("comparator" -> List(
Map("eval" -> "c21",
"operation" -> "equals to",
"when" -> List("A")),
Map("eval" -> "c31",
"operation" -> "equals to",
"when" -> List("A"))),
"operator" -> "OR")),
"operator" -> "OR")),
"then" -> "something"
),
Map("comparison" -> List(
Map("comparison" -> List(
Map("comparator" -> List(
Map(
"eval" -> "c111",
"operation" -> "equals to",
"when" -> List("A")),
Map(
"eval" -> "c121",
"operation" -> "in",
"when" -> List("B", "b"))
),
"operator" -> "AND"),
Map("comparator" -> List(
Map(
"eval" -> "c212",
"operation" -> "equals to",
"when" -> List("A")),
Map(
"eval" -> "c313",
"operation" -> "equals to",
"when" -> List("A"))
),
"operator" -> "OR")),
"operator" -> "AND")),
"then" -> "somethingelse")
),
"else" -> "default"
)
))
def constructCase(c: List[Map[String, Any]], parentOp: Option[String] = None, parentThen: Option[String] = None): String = {
val result = c.map { x =>
val currentOp: Option[String] = x.get("operator").asInstanceOf[Option[String]]
val currentThen: Option[String] = x.get("then").asInstanceOf[Option[String]]
if (x contains "comparator") {
"(" + x("comparator").asInstanceOf[List[Map[String, Any]]].map(x => s"${x("eval")} ${x("operation")} ${x("when").asInstanceOf[List[String]].mkString(",")}").mkString(" " + currentOp.getOrElse("") + " ") + ")"
} else {
val tmp = constructCase(x("comparison").asInstanceOf[List[Map[String, Any]]], currentOp, currentThen)
if (tmp contains "WHEN") tmp else "(" + tmp + ")"
}
}.mkString(if (parentOp.isDefined) s" ${parentOp.get} " else "")
if (parentThen.isDefined) s"WHEN $result THEN ${parentThen.get}\n" else result.trim
}
val samples = Set(sample1, sample2)
samples.foreach { sample =>
val stepsLower = sample.parameters.get.map(p => p._1.toLowerCase -> p._2)
val comparisons = stepsLower("conditional").asInstanceOf[List[Map[String, Any]]]
println("CASE \n" + constructCase(comparisons) + s"\nELSE ${stepsLower("else")}")
println("")
}
Here is the result
CASE
WHEN (((c11 equals to A OR c12 in B OR c13 starts with C) AND (c21 equals to A OR c22 in B)) OR (c31 equals to A OR c32 in B OR c33 starts with C)) THEN result
ELSE default
CASE
WHEN ((c11 equals to A AND c12 in B,b) OR (c21 equals to A OR c31 equals to A)) THEN something
WHEN ((c111 equals to A AND c121 in B,b) AND (c212 equals to A OR c313 equals to A)) THEN somethingelse
ELSE default
Let me know if it doesn't work for any of your use case.