I am parsing the following external XML with Jackson.
<SomeRootObject>
<Events>
<Event>
<EventID>248739296</EventID>
...
<Event>1709</Event>
...
I defined a POJO for “Event”.
@JacksonXmlRootElement(localName = "Event")
public class MyEvent {
@JsonProperty("EventID")
public String eventID;
...
@JsonProperty("Event")
public int event;
...
As you can see one of the fields in this POJO is also mapped as “Event”. And so Jackson complains that it can’t create an int from an event:
com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of int out of START_OBJECT token
at [Source: java.io.StringReader@12417468; line: 1, column: 280] (through reference chain: be.parkd.api.tnt.ram.model.RamEvents[“Event”]->java.util.ArrayList[0]->be.parkd.api.tnt.ram.model.RamEvent[“Event”]).
Can this case be handled with Jackson?
One dirty fix I have in mind is to preprocess the XML to change the underlying Event but I would prefer a cleaner solution.
Variant 1
The following example reads a list of <Event>
elements wrapped in an <Events>
element. The <Event>
itself contains another nested <Event>
element. This seems to be not a problem for Jackson.
Note: I used TypeReference<List<Event>>() {}
as a serialization rule.
@Test
public void test1() throws JsonParseException, JsonMappingException, IOException {
ObjectMapper mapper = new XmlMapper();
List<Event> event=mapper.readValue("<Events><Event><EventID>248739296</EventID><Event>1709</Event></Event><Event><EventID>248739297</EventID><Event>1710</Event></Event></Events>", new TypeReference<List<Event>>() {
});
System.out.println(toString(event));
}
public String toString(Object obj) {
try {
StringWriter w = new StringWriter();
new ObjectMapper().configure(SerializationFeature.INDENT_OUTPUT, true).writeValue(w, obj);
return w.toString();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
With Event.java
@JacksonXmlRootElement(localName = "Event")
public class Event {
@JsonProperty("EventID")
private String eventID;
@JsonProperty("Event")
private int event;
public String getEventID() {
return eventID;
}
public void setEventID(String eventID) {
this.eventID = eventID;
}
public int getEvent() {
return event;
}
public void setEvent(int event) {
this.event = event;
}
}
Prints
[ {
"EventID" : "248739296",
"Event" : 1709
}, {
"EventID" : "248739297",
"Event" : 1710
} ]
So, it works!
Variant 2
@Test
public void test2() throws JsonParseException, JsonMappingException, IOException {
ObjectMapper mapper = new XmlMapper();
SomeRootObject object=mapper.readValue("<SomeRootObject><Events><Event><EventID>248739296</EventID><Event>1709</Event></Event><Event><EventID>248739297</EventID><Event>1710</Event></Event></Events></SomeRootObject>", SomeRootObject.class);
System.out.println(toString(object));
}
With SomeRootObject.class
@JacksonXmlRootElement(localName = "SomeRootObject")
public class SomeRootObject {
@JsonProperty("Events")
List<Event> events;
public SomeRootObject() {
}
public List<Event> getEvents() {
return events;
}
public void setEvents(List<Event> events) {
this.events = events;
}
}
Prints
{
"Events" : [ {
"EventID" : "248739296",
"Event" : 1709
}, {
"EventID" : "248739297",
"Event" : 1710
} ]
}
Works too!
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