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POFailing Polymorphic de-serialization in Jackson with Scala module when polymorphic types are within a Seq()
 

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  1. POFailing Polymorphic de-serialization in Jackson with Scala module when polymorphic types are within a Seq()
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    <p>Given this simple example the third test "de-serialize" fails with the message.</p> <pre><code>Can not construct instance of com.egc.ost.pricing.contracts.response.A, problem: abstract types either need to be mapped to concrete types, have custom deserializer, or be instantiated with additional type information at [Source: java.io.StringReader@1f03691; line: 2, column: 29] com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of com.egc.ost.pricing.contracts.response.A, problem: abstract types either need to be mapped to concrete types, have custom deserializer, or be instantiated with additional type information at [Source: java.io.StringReader@1f03691; line: 2, column: 29] </code></pre> <p>Even though the second test "de-serialize_a" proves that Jackson can resolve the correct polymorphic types.</p> <p>I am using Jackson version and scala module </p> <pre><code> &lt;dependency&gt; &lt;groupId&gt;com.fasterxml.jackson.module&lt;/groupId&gt; &lt;artifactId&gt;jackson-module-scala_2.10&lt;/artifactId&gt; &lt;version&gt;2.2.2&lt;/version&gt; &lt;/dependency&gt; &lt;dependency&gt; &lt;groupId&gt;com.fasterxml.jackson.datatype&lt;/groupId&gt; &lt;artifactId&gt;jackson-datatype-joda&lt;/artifactId&gt; &lt;version&gt;2.2.2&lt;/version&gt; &lt;/dependency&gt; </code></pre> <p>Code:</p> <pre><code>@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.EXTERNAL_PROPERTY, property = "type") @JsonSubTypes(Array( new Type(value = classOf[B], name = "B"), new Type(value = classOf[C], name = "C"))) trait A{} case class B(value : Double) extends A case class C(value : String) extends A case class Owner( results: Seq[(String, A)]) class ATest extends FlatSpec with ShouldMatchers { behavior of "A" it should "serialise" in { val owner : Owner = Owner(Seq(("ExampleB",B(1.0)),("ExampleC",C("One")))) val serialize: String = JsonMarshall.serialize(owner) println(serialize) } it should "de-serialize_a" in { val a: A = JsonMarshall.deserialize[A]("""{ | "type" : "C", | "value" : "One" | }""".stripMargin) println(a) } val json = """{ | "results" : [ [ "ExampleB", { | "type" : "B", | "value" : 1.0 | } ], [ "ExampleC", { | "type" : "C", | "value" : "One" | } ] ] |}""".stripMargin it should "de-serialize" in { val owner: Owner = JsonMarshall.deserialize[Owner](json) println(owner) } } </code></pre>
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    1. COinterestingly if I replace the Seq[(String,A)] with a Map[String,a] and change the json to { "results" : { "ExampleB" : { "type" : "B", "value" : 1.0 },"ExampleC" : { "type" : "C", "value" : "One" }} } it does de-serialize, but... on serialization it drops the type information. It looks like a bug to me.
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