Jackson object mapper includes escape sequence in responses

Question

When I use object mapper, it inluces \r\n in the responses.Help me how to resolve it. I am having train POJO and it has String name and String Value. I set name as "Sydney" and Value as "SYD".It reruns

{\ \ \"name \" : \"Sydney\",\ \ \"Value \" : \"SYD\",\ \ \"isEnable\" : false,\ \ \"isCurrent\" : false\ \ }"

raw value in browser

"{\r\n  \"name\" : \"Sydney\",\r\n  \"name\" : \"SYD\",\r\n  \"isEnable\" : false,\r\n  \"isCurrent\" : false\r\n}"

below is my code Train

public class Train {

    public Train() {
    }


    private String name;
    private String value; 
    private String Code;
    private String countryName;
    private String state;
    private String stateName;
    private boolean isEnable;
    private boolean isCurrent;

    //*getters and setters/*/
    }

Controller calss

public ResponseEntity<String> getDetails(   )       
            throws IOException {
        ResponseEntity<String> responseEntity = null;

        try(StringWriter writer = new StringWriter()) {
            ObjectMapper mapper = new ObjectMapper();           
            Train train = new Train();
          // set name and value to the train object//

             if(train != null)
             {
                mapper.setSerializationInclusion(Inclusion.NON_NULL);
                mapper.setSerializationInclusion(Inclusion.NON_EMPTY);

             mapper.writerWithDefaultPrettyPrinter().writeValue(writer,
                    train);         
            responseEntity = new ResponseEntity<>(writer.toString(),
                    HttpStatus.OK);
             }
             }
          catch()
             {}              
             return responseEntity;
             }

Configuration:

@Override
    public void configureMessageConverters(
            List<HttpMessageConverter<?>> converters) {
        converters.add(extendedJsonConvertor());
        super.configureMessageConverters(converters);
    }

    @Bean
    public MappingJackson2HttpMessageConverter extendedJsonConvertor() {
        MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter = new MappingJackson2HttpMessageConverter();

        mappingJackson2HttpMessageConverter
                .setObjectMapper(getNullAndEmptyFilteredObjectMapper());
        return mappingJackson2HttpMessageConverter;
    }

    @Bean
    public ObjectMapper getNullAndEmptyFilteredObjectMapper() {
        ObjectMapper objectMapper = new ObjectMapper();     
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);
        objectMapper.configure(
                DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        return objectMapper;
    }

When I debug the above code I came to know mapper include those \r\n in the response.Help me how to remove those slashes.

Solution 1

The problem is the line below.

mapper.writerWithDefaultPrettyPrinter().writeValue(writer,train);  

Try replacing it with

mapper.writeValue(writer,train);

Why do you create a new object mapper when you are configuring, MappingJackson2HttpMessageConverter?
You can autowire the object mapper or return the actual object and let spring convert it to json

Solution 2

That's a "simple" double encoding issue i believe. You set a string in the response entity which is again writen as a json response.

If you want to rely on the spring view rendering (mappingjackson2httpmessageconverter) you have to create a response entity for "Train". (Or return a train instance directly from your controller method)

Or you use the way you implemented it and you have to ensure that rendering a string for a json response will not use the jackson message converter, but is left untouched by spring.

Comments

[Haim Raman]

make sure you are using MappingJackson2HttpMessageConverter. what is your spring version

[Haim Raman]

make sure you are actually using this code (place a breakpoint). maybe it's overriding in some place. Try forcing the disable mapper.disable(SerializationFeature.INDENT_OUTPUT);

[Rithik_Star]

@Hamin I defined mapper in configuration class but I am creating instance of mapper through ObjectMapper mapper = new ObjectMapper(); .Will it cuase this issue

[Rithik_Star]

I tried autowiring the object mapper but it return context initialization failed .bcas I am calling those object mapper in configure message converters in configuration class so I am unable to autowired the mapper

[Rithik_Star]

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