support nested property filters

[krishna81m]

Problem: If there is a class say Person

class Person {
   string name;
   int age;
   Address address;

   .. getters and setters
}

How do we dynamically filter specific nested properties: name, address.state, address.zipcode reusing the same object mapper/writer.

One way is to follow the Spring integration to use property filter https://jira.spring.io/browse/SPR-12586. However, nested property filters are not supported. This is because of the way Jackson integration works. This is a very common use case to get only the fields clients are interested in runtime.

There are a few implementations already available that are slow because they lookup the jgen root context to build the nested path every time a property is checked if it can be filtered. These implementations also won't 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 work around 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?

I also ended up writing my own implementation that is fast and that uses SimplePropertyFilter per class built on the nested properties.

The problem really is the way Jackson APIs requests a filter for current property without any context on the current class owning that property.

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

[krishna81m]

Related ticket: https://jira.spring.io/browse/SPR-13622

[cowtowncoder]

This issue does not belong here as filters are implemented by jackson-databind; jackson-core only implements streaming JsonParser, and not databind level property filtering.
You may want to refile this for jackson-databind, along with bit more detail on what changes you would want to see, from perspective of how the filter association should behave.

[krishna81m]

Makes sense, closing this ticket to create one for jackson-databind

[heruan]

FasterXML/jackson-databind#1040

[manojkr001]

It has been a long time since this above question has raised. Any update on support of nested object property filters using Jackson @jsonfilter. @cowtowncoder