Question

I’m developing a REST api which needs to support optional filtering of properties based on a request parameter (based on Spring MVC 3.0.x and Jackson).

What I’m looking into implementing is getting a string parameter (in the format of “fieldName1,fieldName2…”), filtering out property names which aren’t allowed, filtering out property names which don’t exist and adding mandatory properties.

Once I have the final string I want to use the jackson @JSONFilter to seralize only the desired properties like this:

SimpleBeanPropertyFilter someFilter = 
    SimpleBeanPropertyFilter.filterOutAllExcept(builtString);
filterProvider = 
    new SimpleFilterProvider().addFilter("someGenericName",someFilter);
String pojoIntoJsonParse =
    objectMapper.writer(filterProvider).writeValueAsString(pojo);

My questions are:

1. Do I have to use the ModelAndView mechanism (since I’m manipulating the objectMapper on a per request basis) or can I do notify spring of my desired filter somehow and still have it do the heavy lifting?

2. Is this solution feasible performance wise as I think I’ll have to reconstruct the filterProvider and the filter for each request.

3. What are the optimizations (if any) jackson tries to perform with respect to filter caching?

4. Are there any alternative paths I should try to look into with respect to the above problem?

Answer 1

I don’t know enough about Spring to know about ModelAndView part, but I know enough about Jackson to say that the performance is unlikely to be problematic for Jackson filtering.
One reason why filtering approaches are not trivially simple is because they try to balance usability with performance — and as such, both JSON Views and Filters have very low overhead.