Getting issue while parsing json using jackson - json

Question

i am using jackson to parse data i am using following code to parse json
public Map<String, Object> savePreference(#RequestBody Map map) throws IOException{
List preferenceDetails = (List) map.get("data");
int preferenceIndex = 0;
while(preferenceIndex < preferenceDetails.size()){
final ObjectMapper mapper = new ObjectMapper();
System.out.println(preferenceDetails.get(preferenceIndex));
mapper.readValue(preferenceDetails.get(preferenceIndex).toString(), Preference.class);
preferenceIndex++;
}
return null;
}
i am sending json from client side like this
{"data":[
{
"preferenceType":"Travelling"
},
{
"preferenceType":"Shopping"
}
]
}
but above code throws exception when i called
mapper.readValue(preferenceDetails.get(preferenceIndex).toString(), Preference.class);
exception is
com.fasterxml.jackson.core.JsonParseException: Unexpected character ('p' (code 112)): was expecting double-quote to start field name
i am printing preference details in while loop
{preferenceType=Travelling}

Answer 1

You do not need to parse line by line. Using objects directly will be much more easier. Here is a test case which demonstrates how to parse your json to a object directly.
import com.fasterxml.jackson.databind.ObjectMapper;
import org.junit.Assert;
import org.junit.Test;
import java.util.Collection;
public class JacksonTest {
#Test
public void testName() throws Exception {
final String test = "{\"data\":[\n" +
" {\n" +
" \"preferenceType\":\"Travelling\"\n" +
" },\n" +
" {\n" +
" \"preferenceType\":\"Shopping\"\n" +
" }\n" +
" ]\n" +
"}";
final ObjectMapper objectMapper = new ObjectMapper();
final Data data = objectMapper.readValue(test, Data.class);
Assert.assertNotNull(data);
Assert.assertEquals(2, data.getData().size());
}
static class Data {
private Collection<PreferenceType> data;
public Collection<PreferenceType> getData() {
return data;
}
public void setData(Collection<PreferenceType> data) {
this.data = data;
}
}
static class PreferenceType {
private String preferenceType;
public String getPreferenceType() {
return preferenceType;
}
public void setPreferenceType(String preferenceType) {
this.preferenceType = preferenceType;
}
}
}
After that you can build your own map how ever you want. But your framework may be able to handle this kind of request. You do not need to parse it manually. You should try getting Data object directly, instead of getting your body as Map.
Update
Try something like this. But first define Data class properly ( at least not as an inner class).
public Map<String, Object> savePreference(#RequestBody Data data) throws IOException{
...
}
Update 2
And also your map already has your object PreferenceDetail. It may already handle the json and map it as object. Please debug and check if your map.get("data") returns List<PreferenceDetail> or not. If it returns List there is no more work is needed to parse json using jackson. You can simply do something like this.
public Map<String, Object> savePreference(#RequestBody Map map) throws IOException{
List<PreferenceDetail> preferenceDetails = (List) map.get("data");
for (PreferenceDetail preferenceDetail : preferenceDetails) {
System.out.println(preferenceDetail.getPreferenceType());
}
return null;
}

Answer 2

I solved my problem by using jackson object mapper.
public Map<String, Object> savePreference(#RequestBody Map map) throws IOException{
log.debug("saving preferences");
if(preferenceService.getPreferencesByUser() != null && preferenceService.getPreferencesByUser().size() != 0)
return ResponseHandler.generateResponse(configProp.getProperty("user.preference.exist"), HttpStatus.ACCEPTED, true, null);
final ObjectMapper mapper = new ObjectMapper();
List preferenceDetails = (List) map.get("data");
int preferenceIndex = 0;
while(preferenceIndex < preferenceDetails.size()){
preferenceService.savePreference(mapper.readValue(mapper.writeValueAsString(preferenceDetails.get(preferenceIndex)), Preference.class));
preferenceIndex++;
}
return ResponseHandler.generateResponse(configProp.getProperty("preference.added"), HttpStatus.ACCEPTED, true, null);
}