Exclude some field from object while return

Question

I have object that have attributes id, name, description.

In some case i want to return whole object but in some i want to return only id, suppose when I insert new record it should only return id that is newly generated.

public class DTO { private Integer id; private String name; private String description; // getter-setter }

controller:

@RequestMapping(value = "/{cname}/met", method = RequestMethod.POST) @ResponseBody public DTO addMet(@PathVariable String cname, @RequestBody DTO met) { return service.addMet(met); // service return whole DTO object that is newly added with new Id }

I want to return only id as response, so any help or guidance on it that how to do so ?

Thank you.

I didn't understand it. The method addMet cannot return Integer instead of DTO? — Marcelo Keiti
– Marcelo Keiti, Commented Feb 25, 2015 at 2:10
@MarceloKeiti : I want to return response as Json like {id:'1'}, if i ll return it as integer it will just give me id in response. — Java Curious ღ
– Java Curious ღ, Commented Feb 25, 2015 at 2:11
Ok, so return a String and format the DTO instance using some framework like Gson. — Marcelo Keiti
– Marcelo Keiti, Commented Feb 25, 2015 at 2:13

Elliott Frisch · Accepted Answer · 2015-02-25 02:10:39Z

Unless I'm missing something, you could change the return type of the method and return the id with something like

public Integer addMet(@PathVariable String cname, @RequestBody DTO met) { return service.addMet(met).getId(); }

It might be a good idea to log the full return (assuming you have overridden toString())

public Integer addMet(@PathVariable String cname, @RequestBody DTO met) { LOG.debug("Adding: %s", met); DTO r = service.addMet(met); LOG.debug("Result: %s", r); return r.getId(); }

As for your custom class, you could write an inner class like

static class Identity { public Identity(int id) { this.id = id; } private final int id; public int getId() { return id; } public String toString() { return String.format("id: %d", id); } }

and return that

public Identity addMet(@PathVariable String cname, @RequestBody DTO met) { LOG.debug("Adding: %s", met); DTO r = service.addMet(met); LOG.debug("Result: %s", r); return new Identity(r.getId()); }

I want to return response as Json like {id:'1'}, if i ll return it as integer it will just give me id in response.

happyHelper · Accepted Answer · 2015-02-25 02:14:14Z

0

Did you try the JsonIgnore annotation. http://jackson.codehaus.org/1.0.1/javadoc/org/codehaus/jackson/annotate/JsonIgnore.html

answered Feb 25, 2015 at 2:14

happyHelper

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2 Comments

Java Curious ღ Over a year ago

Yes I know this already. But in some situation I want to return whole object and in some I want to just return Id. So it should be kind of dynamic.

happyHelper Over a year ago

maybe this will help then, stackoverflow.com/questions/8179986/… The blog pointed out even has a nice example, I had used it some time back when I was learning.

fps · Accepted Answer · 2015-02-25 04:39:52Z

In your controller, set the fields you want to exclude to null.

Also configure Spring's underlying Jackson ObjectMapper instance to not serialize null fields:

@Configuration public class ServiceContext extends WebMvcConfigurationSupport { @Override public void configureMessageConverters(List<HttpMessageConverter<?>> converters) { MappingJackson2HttpMessageConverter converter = this.getConverter(); converters.add(converter); } @Bean public MappingJackson2HttpMessageConverter getConverter() { MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter(); ObjectMapper mapper = this.getObjectMapper(); converter.setObjectMapper(mapper); return converter; } @Bean public ObjectMapper getObjectMapper() { JsonFactory factory = new JsonFactory(); ObjectMapper mapper = new ObjectMapper(factory); mapper.setSerializationInclusion(Include.NON_NULL); // don't serialize nulls mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES); return factory; } }

iamiddy · Accepted Answer · 2015-02-25 05:04:27Z

You need to use the @JsonView

JSON Views

It can sometimes be useful to filter contextually objects serialized to the HTTP response body. In order to provide such capabilities, Spring MVC now has builtin support for Jackson’s Serialization Views.

Here is a well explained example

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