Here is update to my original post. ignore the above though for most part
they are the same.
copying and pasting from SO is having formatting issues. so I have to
delete couple of my posts above..
I want to serialize/deserialize Record object that has recursive
references. The POJO itself cannot be modified since it is part of legacy
code.
public class Record<T> {
private TypeEnum typeEnum;
private List<T> args;
public Record(TypeEnum typeEnum, List<T> args) {
this.typeEnum = typeEnum;
this.args = args;
}
public TypeEnum getTypeEnum() {
return typeEnum;
}
public void setTypeEnum(TypeEnum typeEnum) {
this.typeEnum = typeEnum;
}
public List<T> getArgs() {
return args;
}
public void setArgs(List<T> args) {
this.args = args;
}
}
enum TypeEnum {
STR("str"),
FOO("foo"),
REC("rec");
private String name;
TypeEnum(String name) {
this.name=name;
}
}
class RecordSerializer extends JsonSerializer<Record> {
@Override
public void serialize(Record record, JsonGenerator jgen,
SerializerProvider serializerProvider) throws IOException {
jgen.writeStartObject();
switch (record.getTypeEnum()) {
case STR:
jgen.writeFieldName(record.getTypeEnum().name());
jgen.writeStartArray();
for (Object arg : record.getArgs()) {
jgen.writeString(arg.toString());
}
jgen.writeEndArray();
break;
case FOO:
jgen.writeFieldName(record.getTypeEnum().name());
jgen.writeStartArray();
for (Object arg : record.getArgs()) {
jgen.writeString(arg.toString());
}
jgen.writeEndArray();
break;
case REC:
jgen.writeFieldName(record.getTypeEnum().name());
jgen.writeStartArray(); // LINE 94
for (Object arg : record.getArgs()) {
serialize((Record) arg, jgen, serializerProvider);
}
jgen.writeEndArray(); // LINE 98
break;
}
jgen.writeEndObject();
}
class RecordDeSerializer extends JsonDeserializer<Record> {
@Override
public Record deserialize(JsonParser jp, DeserializationContext
deserializationContext) throws IOException, JsonProcessingException {
ObjectCodec oc = jp.getCodec();
JsonNode node = oc.readTree(jp);
Iterator<Map.Entry<String, JsonNode>> fields = node.fields
();
while (fields.hasNext()) {
Map.Entry<String, JsonNode> entry = fields.next();
System.out.println(entry.getKey() + "====" + entry.
getValue());
}
return new Record(TypeEnum.STR, Arrays.asList("a", "b", "c"
));
}
}
}
Here is a unit-test that I wrote
@JsonSerialize(keyUsing = RecordSerializer.class)
private Record rec;
ObjectMapper mapper = new ObjectMapper();
public void testSeriaziation() {
Record rec1 = new Record(TypeEnum.STR, Arrays.asList("sup1",
"sup2", "sup3"));
Record rec2 = new Record(TypeEnum.FOO, Arrays.asList("sup4",
"sup5"));
rec = new Record(TypeEnum.REC, Arrays.asList(rec1, rec2));
final String jsonResult = mapper.writeValueAsString(rec);
System.out.println(jsonResult);
}
The output from this test is
{
"REC": [{
"STR": ["sup1", "sup2", "sup3"]
}, {
"FOO": ["sup4", "sup5"]
}]
}
while the expected output is
{
"REC": {
"STR": ["sup1", "sup2", "sup3"],
"FOO": ["sup4", "sup5"]
}}
Notice, I want "STR" and "FOO" to be siblings in root node "REC"
I believe the way I call recursively is wrong. but I cannot figure out what
is wrong.
if I comment out the lines 94 and 98, I get
com.fasterxml.jackson.core.JsonGenerationException: Can not start an
object, expecting field name (context: Object) exception
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