On Thu, Dec 20, 2018 at 1:51 PM matt Smith <matt.smith.11...@gmail.com> wrote:
>
> 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?
But this
"abc" : ["item1", "item2", "item3"]
is not valid JSON value. This
{ "abc" : ["item1", "item2", "item3"] }
would be.
Serializers MUST produce valid JSON values, not fragments, otherwise delegation
will not work.
Your own code can of course compose things using other patterns, but
you should then structure your code in way that matches that.
I hope this helps,
-+ Tatu +-
>
>
> 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> 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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