Retrieving an item from DynamoDB based on id and transforming the item

Question

I'm having a bit of trouble with transforming my item to a "Student" with Jackson ObjectMapper. I've gotten the method to actually get the right item based on the id-parameter sent from the front. So this is the method that works, but doesn't return anything, because I just wanted to test if it works.

AwsService:

public void getStudent(String id){

    Table t = db.getTable(studentTableName);

    GetItemSpec gio = new GetItemSpec()
            .withPrimaryKey("id", id);

    Item item = t.getItem(gio);
    System.out.println("Student: "+item); // <--- Gives the correct item!

}

But now I need it to return a "Student", so instead of void, it should return a Student:

public Student getStudent(String id){

    Table t = db.getTable(studentTableName);

    GetItemSpec gio = new GetItemSpec()
            .withPrimaryKey("id", id);

    Item item = t.getItem(gio);

    //Problem starts here, unsure of how to do. As is, getS() is underlined as error
    Student student = mapper.readValue(item.get("payload").getS(), Student.class);

    return student;
}

Just as a reference I'll add my working method for retrieving all students. So as you can see, I tried to use the same mapper.readValue as in the method for retrieving all students:

public List<Student> getStudents() {

    final List<Student> students = new ArrayList<Student>();

    ScanRequest scanRequest = new ScanRequest()
            .withTableName(studentTableName);

    ScanResult result = client.scan(scanRequest);
    try {
        for (Map<String, AttributeValue> item : result.getItems()) {
            Student student = mapper.readValue(item.get("payload").getS(), Student.class);
            students.add(student);
        }
    } catch (Exception e) {
        throw new RuntimeException(e);
    }

    return students;
}

Answer 1

I figured it out. Here is the correct method for me:

public Student getStudent(String id) throws JsonParseException, JsonMappingException, IOException  {

    Table t = db.getTable(studentTableName);

    GetItemSpec gio = new GetItemSpec()
            .withPrimaryKey("id", id);

    Item item = t.getItem(gio);

    Student student = mapper.readValue(StringEscapeUtils.unescapeJson(item.getJSON("payload").substring(1)), Student.class);

    return student;

}