#24: Fixed JSON mapper bug. (#25)

Fixes #24

Author: morazow

.github/workflows/ci-build.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        scala: [ 2.12.14, 2.13.6 ]
+        scala: [ 2.12.15, 2.13.6 ]
 
     steps:
       - name: Checkout the Repository

build.sbt

@@ -10,7 +10,7 @@ lazy val orgSettings = Seq(
 
 lazy val buildSettings = Seq(
   scalaVersion := "2.13.6",
-  crossScalaVersions := Seq("2.12.14", "2.13.6")
+  crossScalaVersions := Seq("2.12.15", "2.13.6")
 )
 
 lazy val root =

doc/changes/changelog.md

@@ -1,5 +1,6 @@
 # Releases
 
+* [0.3.1](changes_0.3.1.md)
 * [0.3.0](changes_0.3.0.md)
 * [0.2.0](changes_0.2.0.md)
 * [0.1.0](changes_0.1.0.md)

doc/changes/changes_0.3.1.md

@@ -0,0 +1,20 @@
+# Import Export UDF Common Scala 0.3.1, released 2021-10-14
+
+Code name: Fixed JSON Mapper
+
+## Summary
+
+This release fixes parsing bugs in JSON mapper functionality.
+
+## Bug Fixes
+
+* #24: Fixed JSON mapper issues
+
+## Dependency Updates
+
+### Runtime Dependency Updates
+
+### Test Dependency Updates
+
+### Plugin Updates
+

project/Dependencies.scala

@@ -31,6 +31,7 @@ object Dependencies {
       exclude ("org.scala-lang", "scala-reflect"),
     "org.apache.avro" % "avro" % AvroVersion
       exclude ("org.slf4j", "slf4j-api")
+      exclude ("org.apache.commons", "commons-compress")
       excludeAll (
         ExclusionRule(organization = "com.fasterxml.jackson.core"),
         ExclusionRule(organization = "com.fasterxml.jackson.module")

src/main/scala/com/exasol/common/json/JsonMapper.scala

@@ -1,20 +1,67 @@
 package com.exasol.common.json
 
-import com.fasterxml.jackson.core.`type`.TypeReference
+import com.fasterxml.jackson.core.JsonParser
+import com.fasterxml.jackson.databind.MapperFeature
+import com.fasterxml.jackson.databind.SerializationFeature
 import com.fasterxml.jackson.databind.json.{JsonMapper => BaseJsonMapper}
-import com.fasterxml.jackson.module.scala.DefaultScalaModule
+import com.fasterxml.jackson.module.scala.ClassTagExtensions
 
+/**
+ * JSON parsing helper object class.
+ */
 object JsonMapper {
 
-  private[this] val mapper = BaseJsonMapper
-    .builder()
-    .addModule(DefaultScalaModule)
-    .build()
+  private[this] class ScalaJsonMapper(jsonMapper: BaseJsonMapper)
+      extends BaseJsonMapper(jsonMapper)
+      with ClassTagExtensions
 
+  private[this] val mapper = {
+    val builder = BaseJsonMapper
+      .builder()
+      .findAndAddModules()
+      .enable(MapperFeature.ACCEPT_CASE_INSENSITIVE_ENUMS)
+      .enable(JsonParser.Feature.ALLOW_COMMENTS)
+      .defaultMergeable(true)
+    new ScalaJsonMapper(builder.build())
+  }
+
+  /**
+   * Parses given value type into a JSON string.
+   *
+   * For parsing into pretty indented JSON use {@link toPrettyJson}.
+   *
+   * @param value a provided value type
+   * @return JSON string
+   */
   def toJson[T](value: T): String =
     mapper.writeValueAsString(value)
 
+  /**
+   * Parses given value into pretty JSON format.
+   *
+   * @param value a provided value type
+   * @return pretty JSON string
+   */
+  def toPrettyJson[T](value: T): String =
+    mapper.writer(SerializationFeature.INDENT_OUTPUT).writeValueAsString(value)
+
+  /**
+   * Parses JSON string into a type.
+   *
+   * @param jsonString a JSON string
+   * @return parsed value
+   */
+  def fromJson[T: Manifest](jsonString: String): T =
+    mapper.readValue[T](jsonString)
+
+  /**
+   * Parses JSON string into a type.
+   *
+   * @param jsonString a JSON string
+   * @return parsed value
+   */
+  @deprecated("Use fromJson method instead.", "0.3.1")
   def parseJson[T: Manifest](jsonString: String): T =
-    mapper.readValue[T](jsonString, new TypeReference[T]() {})
+    fromJson(jsonString)
 
 }

src/test/scala/com/exasol/common/json/JsonMapperTest.scala

@@ -1,14 +1,39 @@
 package com.exasol.common.json
 
+import java.util.LinkedHashMap
+
+import com.fasterxml.jackson.databind.JsonNode
+
 import org.scalatest.funsuite.AnyFunSuite
 
 class JsonMapperTest extends AnyFunSuite {
 
-  test("parse to and from json to internal data type") {
+  test("parses to/from JSON to internal Scala data type") {
     val jsonStr = """{"name":"John","age":30,"skills":["a","b","c"]}"""
-    val map = JsonMapper.parseJson[Map[String, Any]](jsonStr)
+    val map = JsonMapper.fromJson[Map[String, Any]](jsonStr)
     assert(map.get("skills") === Option(Seq("a", "b", "c")))
     assert(JsonMapper.toJson(map) === jsonStr)
   }
 
+  test("parses to/from JSON to JsonNode") {
+    val jsonStr =
+      """|{
+         |  "number" : 1,
+         |  "record" : {
+         |    "field1" : "value1",
+         |    "field2" : 23
+         |  }
+         |}""".stripMargin
+    val jsonNode = JsonMapper.fromJson[JsonNode](jsonStr)
+    assert(JsonMapper.toPrettyJson(jsonNode) === jsonStr)
+  }
+
+  test("parses to/from JSON to Java LinkedHashMap") {
+    val jsonStr = """{"name":"John","age":"ten"}"""
+    val expected = new LinkedHashMap[String, String](java.util.Map.of("name", "John", "age", "ten"))
+    val parsedMap = JsonMapper.fromJson[LinkedHashMap[String, String]](jsonStr)
+    assert(parsedMap === expected)
+    assert(JsonMapper.toJson(parsedMap) === jsonStr)
+  }
+
 }