Using Spring Boot 1.4.4.RELEASE, have saved a RequestBody to MongoDB as below:
{
"startTime" : NumberLong("1483542955570"),
"startDate" : ISODate("2017-01-04T15:15:55.570Z"),
"endTime" : NumberLong("1483542955570"),
"endDate" : ISODate("2017-01-04T15:15:55.570Z")
}
While mapping this back to a Java POJO, I am trying the below code.
public <T> T getPOJOFromMongoDocument(Document resourceDocument, Class<T> clazz) {
String serialize = JSON.serialize(resourceDocument);
return objectMapper.readValue(serialize,
clazz);
}
serialize has the date fields returned as following
"startDate" : { "$date" : "2017-01-04T15:15:55.570Z"}
Due to $date, Jackson ObjectMapper returns the below exception during parsing:
java.lang.RuntimeException: Error parsing mongoDoc to Pojo : errorMessage : {Can not deserialize instance of java.util.Date out of START_OBJECT token at [Source: {
"startTime": 1483542955570,
"startDate": {
"$date": "2017-01-04T15:15:55.570Z"
},
"endTime": 1483542955570,
"endDate": {
"$date": "2017-01-04T15:15:55.570Z"
}}; line: 1, column: 381] (through reference chain: com.gofynd.engine.mongo.models.RuleWithDataVO["validity"]->com.gofynd.engine.mongo.models.ValidityVO["startDate"])}
Is there way to solve this without using an ODM?
When deserializing to Date Jackson expects a String like "2017-01-04T15:15:55.570Z". Instead, it sees the start of another object (the { char) inside the JSON hence the exception.
Consider specifying your Pojo class and another MongoDate class similar to this:
class MongoDate {
@JsonProperty("$date")
Date date;
}
class Pojo {
long startTime;
long endTime;
MongoDate startDate;
MongoDate endDate;
}
Alternatively if you can't / don't want to add a MongoDate class you can introduce a custom deserializer for Date fields. In that case Pojo:
class Pojo {
long startTime;
long endTime;
@JsonDeserialize(using = MongoDateConverter.class)
Date startDate;
@JsonDeserialize(using = MongoDateConverter.class)
Date endDate;
}
And the deserializer would look like this:
class MongoDateConverter extends JsonDeserializer<Date> {
private static final SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
@Override
public Date deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException {
JsonNode node = jp.readValueAsTree();
try {
return formatter.parse(node.get("$date").asText());
} catch (ParseException e) {
return null;
}
}
}
I went back and tried a similar approach of using a deserializer.
Here's the code:
public class MongoDateDeserializer extends JsonDeserializer<Date> {
@Override
public Date deserialize(JsonParser jsonParser, DeserializationContext deserializationContext)
throws IOException {
ObjectCodec oc = jsonParser.getCodec();
JsonNode node = oc.readTree(jsonParser);
String dateValue = node.get("$date")
.asText();
DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
Date date = null;
try {
date = df.parse(dateValue);
} catch (ParseException e) {
e.printStackTrace();
}
return date;
}}
Changes in VO are are as below:
@JsonDeserialize(using = MongoDateDeserializer.class)
private Date startDate;
@JsonDeserialize(using = MongoDateDeserializer.class)
private Date endDate;
This has worked successfully. However, would be better if MongoDB's JSON.serialize does the job of returning a normalized json. Hopefully in future.