I'm trying to convert xml into json using jackson-2.5.1
and jackson-dataformat-xml-2.5.1
The xml structure is received from web server and unknown, therefore I can't have java class to represent the object, and I'm trying to convert directly into TreeNode
using ObjectMapper.readTree
.
My problem is jackson failing to parse lists. It is takes only the last item of the list.
code:
String xml = "<root><name>john</name><list><item>val1</item>val2<item>val3</item></list></root>";
XmlMapper xmlMapper = new XmlMapper();
JsonNode jsonResult = xmlMapper.readTree(xml);
The json result:
{"name":"john","list":{"item":"val3"}}
If I enable failure on duplicate keys xmlMapper.enable(DeserializationFeature.FAIL_ON_READING_DUP_TREE_KEY)
, exception is thrown:com.fasterxml.jackson.databind.JsonMappingException: Duplicate field 'item' for ObjectNode: not allowed when FAIL_ON_READING_DUP_TREE_KEY enabled
Is there any feature which fixes this problem? Is there a way for me to write custom deserializer which in event of duplicate keys turn them into array?
I use this approach:
size==1
.Here is my code:
@Test
public void xmlToJson() {
String xml = "<root><name>john</name><list><item>val1</item>val2<item>val3</item></list></root>";
Map<String, Object> jsonResult = readXmlToMap(xml);
String jsonString = toString(jsonResult);
System.out.println(jsonString);
}
private Map<String, Object> readXmlToMap(String xml) {
try {
ObjectMapper xmlMapper = new XmlMapper();
xmlMapper.registerModule(new SimpleModule().addDeserializer(Object.class, new UntypedObjectDeserializer() {
@SuppressWarnings({ "unchecked", "rawtypes" })
@Override
protected Map<String, Object> mapObject(JsonParser jp, DeserializationContext ctxt) throws IOException {
JsonToken t = jp.getCurrentToken();
Multimap<String, Object> result = ArrayListMultimap.create();
if (t == JsonToken.START_OBJECT) {
t = jp.nextToken();
}
if (t == JsonToken.END_OBJECT) {
return (Map) result.asMap();
}
do {
String fieldName = jp.getCurrentName();
jp.nextToken();
result.put(fieldName, deserialize(jp, ctxt));
} while (jp.nextToken() != JsonToken.END_OBJECT);
return (Map) result.asMap();
}
}));
return (Map) xmlMapper.readValue(xml, Object.class);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
static public String toString(Object obj) {
try {
ObjectMapper jsonMapper = new ObjectMapper().configure(SerializationFeature.INDENT_OUTPUT, true)
.configure(SerializationFeature.WRITE_SINGLE_ELEM_ARRAYS_UNWRAPPED, true);
StringWriter w = new StringWriter();
jsonMapper.writeValue(w, obj);
return w.toString();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
It prints
{
"list" : {
"item" : [ "val1", "val3" ]
},
"name" : "john"
}
Altogether it is a variante of this approach, which comes out without guava multimap: https://github.com/DinoChiesa/deserialize-xml-arrays-jackson
Same approach is used here: Jackson: XML to Map with List deserialization
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