[spec] introduce null-save JsonObjectBuilder.add and JsonGenerator.write methods

[struberg]

I'm missing a set of methods in both JsonGenerator and JsonObjectBuilder to fluently deal with null values. E.g. if you look at JsonObjectBuilder.add [1] then you'll notice that it throws a NullPointerException if the value is null.

This is sometimes a bit inconvenient. Especially if one wants to represent some information from a DTO or entity into JSON. Note that JSON-B is out or scope for my use case. Such a code has to check every single attribute and either use addNull (resp writeNull) or skip the whole attribute if the value is null. This destroys the fluentness of the whole API. Also note that some methods like JsonGenerator#write(String, String) [2] are not defined to throw a NullPointerException in case the value is null. But with others like write(String, int) the NPE already happens during auto-boxing.

I'd rather prefer to have JsonGenerator#write* and JsonObjectBuilder#add* consistently throw NPE, but have an additional set of methods with optionalAdd(String key, Integer value, boolean skipIfNull)

That way we would end up with something like:

jsonObjectBuilder
    .add("id", person.getId())  // mandatory
    .optionalAdd("name", person.getName(), true)
    .optionalAdd("age", person.getAge(), true)
    .build();

And similar methods for JsonGenerator#optionalWrite(...)

[1] https://javaee.github.io/javaee-spec/javadocs/javax/json/JsonObjectBuilder.html#add-java.lang.String-java.lang.String- [2] https://javaee.github.io/javaee-spec/javadocs/javax/json/stream/JsonGenerator.html#write-java.lang.String-java.lang.String-

[struberg]

PS: yes, this would add complexity to our interfaces. I know it's not perfect, so I'm happy if someone comes up with a better solution!

[keijack]

I agree with @struberg , it's not convenient to use sometimes. If optionalAdd may add complexity to the interface, what if provide a configuration, and let the implementation to do the job.

Map<String, ?> conf = new HashMap<>();
conf.put(JsonBuilderFactory.IGNORE_ADDING_IF_NULL, true);
JsonBuilderFactory fac = Json.createBuilderFactory(conf);
fac.createObjectBuilder()
        .add("name", person.getName())
        .add("age", person.getAge())
        .build();

[jbescos]

• [ ] TCK