Jackson unrecognized field exception but field is in JSON

Question

I am using Spring Integration to consume a message with a JSON Payload.

In my spring context I have

<integration:channel id="jsonToMyMessageConverterChannel"/>
<integration:json-to-object-transformer 
    type="com.acme.messaging.message.MyMessage"
    input-channel="jsonToMyMessageConverterChannel"
    output-channel="myMessageUpdateChannel"/>

My message related objects are:

MyMessage.java

@JsonIgnoreProperties(ignoreUnknown=true)
public class MyMessage {

    @JsonProperty
    private String timestamp;

    @JsonProperty("msgs")
    private List<Message> messages;

    // Getters and Setters...
}

Message.java

@JsonIgnoreProperties(ignoreUnknown=true)
public class Message {

    @JsonProperty
    private Integer msgId;

    @JsonProperty("msgText")
    private String text;

    // Getters and Setters...
}

When the json transformer attempts to convert the message to an object it fails with

Caused by: org.codehaus.jackson.map.exc.UnrecognizedPropertyException: Unrecognized field "msgs" (Class com.acme.messaging.message.MyMessage), not marked as ignorable

The JSON payload definitely has msgs which is an array that has objects which represent the Message.java class.

Can any one suggest reasons why the exception occurs given that the JSON has the field that is being complained about and the class itself is also annotated to ignore unknown fields?

Update After some debugging it looks like the @JsonProperty("msgs") annotations aren't being use, for some reason.

Solution

This works fine for me...

@Test
public void test() throws Exception {
    MyMessages mm = new MyMessages();
    MyMessage m = new MyMessage();
    m.setMsgId(1);
    m.setText("foo");
    mm.setMessages(Arrays.asList(m));
    mm.setTimestamp("123");
    @SuppressWarnings("deprecation")
    ObjectToJsonTransformer otjt = new ObjectToJsonTransformer(new ObjectMapper());
    Message<?> message = new GenericMessage<MyMessages>(mm);
    message = otjt.transform(message);
    System.out.println(message);
    @SuppressWarnings("deprecation")
    JsonToObjectTransformer<MyMessages> jtot = new JsonToObjectTransformer<MyMessages>(MyMessages.class, new ObjectMapper());
    message = jtot.transform(message);
    mm = (MyMessages) message.getPayload();
    System.out.println(mm.getTimestamp());
    System.out.println(mm.getMessages().get(0).getText());
}

(I changed your classnames slightly to avoid colliding with Message<?>)

Resulting in...

[Payload={"timestamp":"123","msgs":[{"msgId":1,"msgText":"foo"}]}][Headers={timestamp=1373997151738, id=f2425f36-a500-4aee-93a4-e7e0240ce0f1, content-type=application/json}]
123
foo

Do you have both jackson 1.x (codehaus) and 2.x (fasterxml) on the classpath, and using Spring Integration 3.0.0?

If they're both on the classpath, SI will use Jackson 2.x, by default, (which won't understand 1.x annotations).

Or, I guess - are you using Jackson2 (fasterxml) annotations? Spring Integration 2.x uses Jackson 1 (codehaus).

EDIT:

In order to support both versions of Jackson, you can annotate the class with both annotations...

    @JsonProperty("msgs")
    @com.fasterxml.jackson.annotation.JsonProperty("msgs")
    public List<MyMessage> messages;

Comments

[C0deAttack]

I am using Spring Integration 2.2.3, Fasterxml Jackson (core|databind|annotations) 2.2.1 and Codehaus Jackson (mapper-asl|core-asl) 1.7.4. The @JsonProperty annotation is imported from jackson-annotations-2.2.1. So your last comment might be the reason, I will investigate.

[C0deAttack]

You comment at the bottom led me to the solution. I didn't know that Spring Integration 2.x used Codehaus Jackson (1.9.x). I had imported the Fastxml Jackson classes instead. Thanks!

[Gary Russell]

I edited the answer indicating you can add both sets of annotations.