CODEWITHSUNDEEP
javaspringrestspring-bootjax-rs
kros365
kros365

Reputation: 105

Spring hateoas jaxrslinkbuilder adds null fields

I am trying to add HATEOAS links to my Controller results. Link creation:

       Link link = JaxRsLinkBuilder.linkTo(MainRestService.class)
                    .slash(this::getVersion)
                    .slash(LinkMappingConstants.TAXPAYERS)
                    .slash(taxPayerId)
                    .slash(LinkMappingConstants.ESTIMATIONS)
                    .slash(estimationId)
                    .withSelfRel();

The link itself is created fine, but there are superfluous entries in the resulting JSON:

"links": [
        {
          "rel": "self",
          "href": "http://localhost:8080/blablabla",
          "hreflang": null,
          "media": null,
          "title": null,
          "type": null,
          "deprecation": null,
          "template": {
            "variables": [

            ],
            "variableNames": [

            ]
          }
        }
      ]

How can i get this format? (without use property spring.jackson.default-property-inclusion=NON_NULL)

"links": [
        {
          "rel": "self",
          "href": "http://localhost:8080/blablabla"
        }
      ]

Thanks.

Upvotes: 1

Views: 484

Answers (1)

MarkRobbo
MarkRobbo

Reputation: 1015

As you mention, if you want NON_NULL property inclusion on the whole JSON and not just links you can use spring.jackson.default-property-inclusion=NON_NULL. This won't fix the empty template fields however.

If you want to have NON_NULL property inclusion on just the Link object using Jackson for serialization you can achieve this by using a Jackson MixIn for the Link object with the @JsonInclude(Include.NON_NULL) annotation.

As an example:

@JsonInclude(Include.NON_NULL)
abstract class LinkMixIn {
}

mapper.addMixIn(Link.class, LinkMixIn.class);

To hide the template fields you can either add @JsonIgnore if you never want the template section to be serialized, or try NON_DEFAULT property inclusion on the above answer which creates a new instance of the object and compares it to what is to be serialized to determine if it should be included.

E.g. something like the following would not serialize the result of getTemplate at all

@JsonInclude(Include.NON_NULL)
abstract class LinkMixIn {
    @JsonIgnore abstract Template getTemplate();
}

Upvotes: 1

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