support nested property filters using Jackson [SPR-13622]

[spring-projects-issues]

rk opened SPR-13622 and commented

#17187 already supports filters but the underlying code does not filter nested properties because of the way Jakson and its spring integration works, there should be a custom filter to support simple nested property filtering (without any regular expressions). This is a very common use case to get only the fields clients are interested in runtime.

There are a few complex implementations already available, but these are not compatible with MappingJacksonValue as a drop in replacement, i.e., we cannot set their Filter implementations to MappingJacksonValue and expect them to work without explicitly adding JsonFilter annotation on all classes that will be filtered:
https://github.com/PressAssociation/partial-response/tree/master/filter-json-jackson
https://github.com/Antibrumm/jackson-antpathfilter
https://github.com/narusas/SpringMvcJacksonFilter

The following won't work without @JsonFilter("antPathFilter") on all classes

objectMapper.addMixIn(Object.class, AntPathFilterMixin.class);

filter = new SimpleFilterProvider()
			.addFilter("antPathFilter",
					new AntPathPropertyFilter("nestedObj", "nestedObj.nestedProperty")

jacksonValue.setFilters(filter);
		

One hack is to explicitly set the same @JsonFilter("antPathFilter") on all classes that are nested, which did not make any sense to me. What if I wanted to support multiple filters at the same time tomorrow?

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No further details from SPR-13622

[spring-projects-issues]

rk commented

Ended up writing a workaround that uses SimplePropertyFilter per class built on the nested properties. The problem is apparently the way Jackson APIs requests a filter for the current property without any context on the current class owning that property. Will file a ticket with Jackson.

https://github.com/krishna81m/jackson-nested-prop-filter

[spring-projects-issues]

Sébastien Deleuze commented

I also feel that this should be improved as Jackson level rather than at Spring level.
Could you please post here the link of the Jackson issue when it will be created?

[spring-projects-issues]

rk commented

Related ticket: FasterXML/jackson-core#230

[spring-projects-issues]

Sébastien Deleuze commented

This issue has been discussed on Jackson side.