On Sun, Oct 14, 2018 at 12:58 PM Volkan Yazıcı <volkan.yaz...@gmail.com> wrote:
>
> God bless you Tatu! Worked like a charm!
> Given below snippet, would you mind checking one more time that I am not
> doing something stupid, please?
>
> public static void main(String[] args) throws IOException {
>
> // Create the delegate.
> ObjectMapper objectMapper = new ObjectMapper();
> JsonFactory jsonFactory = new JsonFactory(objectMapper);
> ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
> JsonGenerator jsonGenerator = jsonFactory.createGenerator(outputStream);
> NullExcludingTokenFilter tokenFilter = new NullExcludingTokenFilter();
> FilteringGeneratorDelegate generatorDelegate = new
> FilteringGeneratorDelegate(jsonGenerator, tokenFilter, true, true);
>
> // Start the object.
> generatorDelegate.writeStartObject();
>
> // Write a non-empty field.
> generatorDelegate.writeStringField("foo", "bar");
>
> // Write a null-valued field.
> generatorDelegate.writeFieldName("baz");
> generatorDelegate.writeNull();
>
> // Write {"x": {"y": []}}.
> generatorDelegate.writeFieldName("x");
> generatorDelegate.writeStartObject();
> generatorDelegate.writeFieldName("y");
> generatorDelegate.writeStartArray();
> generatorDelegate.writeEndArray();
> generatorDelegate.writeEndObject();
>
> // End the object.
> generatorDelegate.writeEndObject();
>
> // Generate the JSON.
> jsonGenerator.flush();
> String json = outputStream.toString("UTF-8");
> System.out.println(json);
>
> }
>
> private static class NullExcludingTokenFilter extends TokenFilter {
>
> @Override
> public boolean includeNull() {
> return false;
> }
>
> }
Ah! I had forgotten there actually already was this quite specific
filtering option!!! :-D
Yes, that looks legit, thank you for sharing.
-+ Tatu +-
>
>
>
>
> On Saturday, October 13, 2018 at 11:21:02 PM UTC+2, Tatu Saloranta wrote:
>>
>> On Sat, Oct 13, 2018 at 1:22 PM Volkan Yazıcı <volkan...@gmail.com> wrote>
>>
>> > While using `JsonGenerator`, how can I exclude empty/null/blank object
>> > fields?
>> >
>> > (I have asked the very same question on SO as well, but could not get any
>> > answer yet. Hence the cross-post.)
>>
>> By not writing them.
>>
>> That is, generator writes exactly what you ask it to. It is possible
>> to implement a `JsonGeneratorDelegate`
>> that could block calls, and in fact `FilteringGeneratorDelegate` does
>> this to allow structural exclusion/inclusion.
>>
>> -+ Tatu +-
>
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