How to render null elements in List as empty in @ResponseBody?

Asked Jul 05 '17 at 14:41

Active Jul 05 '17 at 14:50

Viewed 213 times

How can I render a null element of a list as empty element in a json POST response?

@PostMapping("/")
@ResponseBody
public MyRsp test() {
    MyRsp rps = new MyRsp();
    rsp.setList(Arrays.asList("one", "two", null, "four");
    return rsp;

}

@JsonInclude(Include.NON_NULL)
public class MyRsp {
    @JsonInclude(Include.NON_NULL)
    private List<String> list;
}

Result:

{
   list: [
     "one",
     "two",
     null,
     "four"
   ]
}

I'm already using the following property:

spring.jackson.default-property-inclusion=non_null.

What else could I do?

edited Jul 05 '17 at 14:50

asked Jul 05 '17 at 14:41

membersound

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1

What is `` in JSON? – Usagi Miyamoto Jul 05 '17 at 14:43
I just ment to write: it should just render as an empty element. like: `one, two, , four`. – membersound Jul 05 '17 at 14:45
The linked question advises the use of `@JsonInclude(Include.NON_NULL)`. I tried it, but did not work. Especially the propert state above `non_null` should already handle this. And indeed it works for `XML` responses, but not for `JSON`. – membersound Jul 05 '17 at 14:49
1

Your "empty element" is invalid JSON syntax... – Usagi Miyamoto Jul 05 '17 at 14:54
https://stackoverflow.com/questions/12934045/null-values-as-empty-strings-when-using-responsebody-annotation – Mykola Yashchenko Jul 05 '17 at 14:56
@UsagiMiyamoto well how do I then represent "non existing" elements inside a collection in `json`? Or is `null` indeed the proper representation to set missing elements in a collection at a specific index. – membersound Jul 05 '17 at 15:02
https://www.w3schools.com/js/js_json_datatypes.asp – Usagi Miyamoto Jul 05 '17 at 15:06
1

This is a `List` and you want the corresponding JSON array to have an empty string in that position instead of `null`? – Sotirios Delimanolis Jul 05 '17 at 15:08
1

If a `""` is acceptable instead of `null`, [this answer](https://stackoverflow.com/a/5868683/592355) might help! – xerx593 Jul 05 '17 at 15:16
@SotiriosDelimanolis exactly. – membersound Jul 05 '17 at 16:11
have a look at https://stackoverflow.com/questions/21120999/representing-null-in-json – Shantaram Tupe Jul 06 '17 at 11:49

How to render null elements in List as empty in @ResponseBody?

0 Answers0