Play mapping returns empty string instead of key for RepeatedMappings type

[KeivanAbdi]

Play Version

2.9.0-M7 (also tested on 2.8.20 and it exists there too)

API

Scala 2.13.11

Operating System

macOS 13.5.1

JDK

openjdk 17.0.8.1 2023-08-24

There is a bug in the Play mapping. Consider this as a sample mapping:

tuple(
    "a1" -> single("a2" -> nonEmptyText),
    "a3" -> list(text),
    "a4" -> number
)

We should be able to read the keys from this mapping. But instead of a3 we get an empty string.

This is a sample method for traversing the mappings and getting their keys:

def mappingFieldAddresses(mapping: Mapping[_]): Seq[String] = {

    var vector: Vector[String] = Vector.empty

    def processMapping(mapping: Mapping[_], depth: Int = 0): Unit = {
      if (mapping.mappings.size == 1) {
        vector = vector.appended(mapping.key)
      }
      if (depth == 0 || mapping.mappings.size == 1) {
        mapping.mappings.tail.foreach(processMapping(_, depth + 1))
      }
    }

    processMapping(mapping)

    vector
  }

To reproduce the bug, follow these steps:

• Call mappingFieldAddresses with the sample mapping as an argument
• Observe the returned sequence of strings

The expected behavior is:

• The returned sequence should contain the keys of the mapping, such as Vector("a1.a2", "a3", "a4")

The actual behavior is:

• The sequence contains an empty string instead of a3, such as Vector("a1.a2", "", "a4")

I have a solution that fixes this bug and passes all the tests. But I'm not sure if it is making any unpredicted new issues. I will create a pull request soon and reference this issue. Please let me know if you have any feedback or suggestions on my solution. I appreciate your help and cooperation.