I am serializing `i` which would be "abc" : ["item1", "item2", item3"].
`i` is object here and I have defined in same serializer how to serialize
"this" object
do you want the example checked into github for quick run?
On Thursday, December 20, 2018 at 1:44:45 PM UTC-8, Tatu Saloranta wrote:
>
> On Thu, Dec 20, 2018 at 1:28 PM matt Smith <matt.smi...@gmail.com
> <javascript:>> wrote:
> >
> > I added as comments beside each line in the else block below. that is
> what I expect it to work. is my expectation in any of those lines?
>
> Almost right, with one incorrect one:
>
> >
> > if (items.isEmpty()) {
> > jgen.writeStartObject();
> > jgen.writeFieldName(id);
> > jgen.writeStartArray();
> > jgen.writeEndArray();
> > jgen.writeEndObject();
> > }
> > else {
> > jgen.writeStartObject(); // '{'
> > Object item = items.get(0);
> > jgen.writeFieldName(id);
> //"combined"
> > if (item instanceof ItemRow){
> > for (Object i : items) {
> > jgen.writeStartObject(); // "{"
> > jgen.writeObject(i); //
> "abc" :["item1","item2", "item2"]
>
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^'
>
>
> "abc" is not output -- you are asking for value `i` to be serialized as a
> value.
> Not as property-name/value pair.
> So if you expect "abc" in there, you need to call `writeFieldName("abc")`
>
> -+ Tatu +-
>
> > jgen.writeEndObject(); // "}"
> >
> >
> >
> > On Thursday, December 20, 2018 at 11:32:55 AM UTC-8, matt Smith wrote:
> >>
> >> here is the class that I want to serialize.
> >>
> >>
> >> public class ItemRow<T> {
> >>
> >> private String id;
> >> private List<T> items;
> >> }
> >>
> >>
> >> There are two variations that are allowed.
> >>
> >> `ItemRow<String>, ItemRow<ItemRow>`.
> >>
> >> In the latter case, it will be nested.
> >>
> >> eg:
> >>
> >>
> >> ItemRow item1 = new ItemRow("abc", Arrays.asList("item1", "item2",
> "item3"));
> >> String result = mapper.writeValueAsString(item1);
> >> System.out.println(result);
> >>
> >>
> >>
> >> should give
> >>
> >>
> >> {"abc":["item1","item2","item3"]}
> >>
> >>
> >>
> >> Now, the latter case
> >>
> >>
> >> ItemRow item2 = new ItemRow("cde", Arrays.asList("item4, item5"));
> >> ItemRow item = new ItemRow("combined", Arrays.asList(item1,item2));
> >> result = mapper.writeValueAsString(item);
> >> System.out.println(result);
> >>
> >>
> >> should give
> >>
> >>
> >> {
> >> "combined": {
> >> "abc": ["item1", "item2", "item3"],
> >> "cde": ["item4", "item5"]
> >> }
> >> }
> >>
> >>
> >> But I get exception while serializing the latter. The first one works
> as expected. so I believe the recursive serialization is failing, but I am
> unable to find out why
> >>
> >> Here is exception
> >>
> >>
> >> com.fasterxml.jackson.core.JsonGenerationException: Can not start an
> object, expecting field name (context: Object)
> >>
> >> at
> com.fasterxml.jackson.core.JsonGenerator._reportError(JsonGenerator.java:1961)
>
>
> >> at
> com.fasterxml.jackson.core.json.JsonGeneratorImpl._reportCantWriteValueExpectName(JsonGeneratorImpl.java:244)
>
>
> >> at
> com.fasterxml.jackson.core.json.WriterBasedJsonGenerator._verifyValueWrite(WriterBasedJsonGenerator.java:866)
>
>
> >> at
> com.fasterxml.jackson.core.json.WriterBasedJsonGenerator.writeStartObject(WriterBasedJsonGenerator.java:279)
>
>
> >> at hello.ItemRowSerializer.serialize(ItemRow.java:58)
> >> at hello.ItemRowSerializer.serialize(ItemRow.java:42)
> >> at
> com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:480)
>
>
> >> at
> com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:319)
>
>
> >> at
> com.fasterxml.jackson.databind.ObjectMapper.writeValue(ObjectMapper.java:2655)
>
>
> >> at
> com.fasterxml.jackson.core.base.GeneratorBase.writeObject(GeneratorBase.java:381)
>
>
> >> at hello.ItemRowSerializer.serialize(ItemRow.java:67)
> >> at hello.ItemRowSerializer.serialize(ItemRow.java:42)
> >>
> >>
> >> Serializer implementation
> >>
> >>
> >> class ItemRowSerializer extends JsonSerializer<ItemRow> {
> >>
> >> @Override
> >> public void serialize(ItemRow itemRow, JsonGenerator jgen,
> SerializerProvider serializerProvider) throws IOException {
> >>
> >> String id = itemRow.getId();
> >> List<Object> items = itemRow.getItems();
> >>
> >> if (items.isEmpty()) {
> >> jgen.writeStartObject();
> >> jgen.writeFieldName(id);
> >> jgen.writeStartArray();
> >> jgen.writeEndArray();
> >> jgen.writeEndObject();
> >> }
> >> else {
> >> jgen.writeStartObject();
> >> Object item = items.get(0);
> >> jgen.writeFieldName(id);
> >> if (item instanceof ItemRow){
> >> for (Object i : items) {
> >> //ItemRow temp = (ItemRow) i;
> >> //jgen.writeObjectField(temp.getId(), temp);
> >> //jgen.writeObjectField(id, i);
> >> jgen.writeStartObject();
> >> jgen.writeObject(i);
> >> jgen.writeEndObject();
> >> }
> >> }
> >> else {
> >> //jgen.writeFieldName(id);
> >> jgen.writeStartArray();
> >> for (Object arg : items) {
> >> jgen.writeString(arg.toString());
> >> }
> >> jgen.writeEndArray();
> >> }
> >> }
> >> jgen.writeEndObject();
> >> }
> >> }
> >>
> >>
> >>
> >>
> >>
> >>
> >>
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