Question

Is it possible to selectively determine when the @JsonFilter annotation gets used at runtime?

I’m getting JsonMappingException exception (see below) when I don’t provide the filter.

Background:

I learned from a recent StackOverflow post that I can use @JsonFilter to dynamically filter the bean properties getting serialized. This works great. After adding @JsonFilter("apiFilter") to my domain class and with the addition of this code in my jax-rs service (using the CXF implementation), I am able to dynamically filter the properties returned by my RESTful API:

// shortened for brevity
FilterProvider filters = new SimpleFilterProvider().addFilter("apiFilter", SimpleBeanPropertyFilter.filterOutAllExcept(filterProperties));

return mapper.filteredWriter(filters).writeValueAsString(user);

The problem is there are different service calls where I don’t want to apply the filter at all. In those cases I want to return the entire domain class without filtering any properties. In the case where I just try to return the domain class I’m getting an exception as follows:

Caused by: org.codehaus.jackson.map.JsonMappingException: Can not resolve BeanPropertyFilter with id 'apiFilter'; no FilterProvider configured

at org.codehaus.jackson.map.ser.BeanSerializer.findFilter(BeanSerializer.java:252)
at org.codehaus.jackson.map.ser.BeanSerializer.serializeFieldsFiltered(BeanSerializer.java:216)
at org.codehaus.jackson.map.ser.BeanSerializer.serialize(BeanSerializer.java:140)

Answer 1

I think you could trick the filtered writer defining an empty serialize filter for the cases where you want all the properties seralized:

FilterProvider filters = new SimpleFilterProvider().addFilter("apiFilter", SimpleBeanPropertyFilter.serializeAllExcept(emptySet));

This way, when the engine looks for the “apiFilter” filter defined at the @JsonFilter anotation, it finds it, but it will not have any effect (as will serialize all the properties).

EDIT
Also, you can call the factory method writer() instead of filteredWriter():

ObjectWriter writer=null;
if(aplyFilter) {
    FilterProvider filters = new SimpleFilterProvider().addFilter("apiFilter", SimpleBeanPropertyFilter.filterOutAllExcept(filterProperties));
    writer=mapper.filteredWriter(filters);
} else {
   writer=mapper.writer();
}

return writer.writeValueAsString(user);

I think this last solution is way cleaner, and indeed better.