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Can not store list of objects as single column JSON

I'm trying to store a whole array of object into one field on my oracle database, I'm referring to the solution on this question, but it kept giving me Can not set java.lang.String field xxx.demo.Models.Sensors.amplitudos to xxx.demo.Models.Sensors error, I have checked the JSON body and the entity class, but I cannot find the mistake.
Here is my code.
entity
#Entity
#Table(name = "SENSOR")
public class Sensor implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
#Column(name = "TIMERECEIVED")
private Timestamp timereceived;
#Column(name = "SENSORS")
private Sensors[] sensors;
#Column(name = "LOC")
private String location;
public Sensor() {
}
public Sensor(Timestamp timereceived, Sensors[] sensors, String location) {
this.timereceived = timereceived;
this.sensors = sensors;
this.location = location;
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public Timestamp getTimereceived() {
return timereceived;
}
public void setTimereceived(Timestamp timereceived) {
this.timereceived = timereceived;
}
public Sensors[] getSensors() {
return sensors;
}
public void setSensors(Sensors[] sensors) {
this.sensors = sensors;
}
public String getLocation() {
return location;
}
public void setLocation(String location) {
this.location = location;
}
}
Sensors class
#Embeddable
public class Sensors {
private String amplitudos;
private Double displacement;
private String frequencies;
private Integer sensorId;
public Sensors() {
}
public Sensors(String amplitudos, Double displacement, String frequencies, Integer sensorId) {
this.amplitudos = amplitudos;
this.displacement = displacement;
this.frequencies = frequencies;
this.sensorId = sensorId;
}
public String getAmplitudos() {
return amplitudos;
}
public void setAmplitudos(String amplitudos) {
this.amplitudos = amplitudos;
}
public Double getDisplacement() {
return displacement;
}
public void setDisplacement(Double displacement) {
this.displacement = displacement;
}
public String getFrequencies() {
return frequencies;
}
public void setFrequencies(String frequencies) {
this.frequencies = frequencies;
}
public Integer getSensorId() {
return sensorId;
}
public void setSensorId(Integer sensorId) {
this.sensorId = sensorId;
}
}
my JSON body
{
"timereceived": "2022-11-29T12:04:42.166",
"sensors": [
{
"amplitudos": "a1#a2#a3#a4",
"displacement": 0.002,
"frequencies": "f1#f2#f3#f4",
"sensorid": 1
},
{
"amplitudos": "a1#a2#a3#a4",
"displacement": 0.002,
"frequencies": "f1#f2#f3#f4",
"sensorid": 2
},
{
"amplitudos": "a1#a2#a3#a4",
"displacement": 0.002,
"frequencies": "f1#f2#f3#f4",
"sensorid": 3
},
{
"amplitudos": "a1#a2#a3#a4",
"displacement": 0.002,
"frequencies": "f1#f2#f3#f4",
"sensorid": 4
}
],
"location": "lokasi"
}
my controller
#PostMapping("/sendData")
public ResponseEntity sendData(#RequestBody Sensor sensor) {
Sensor newSensor = sensorRepository.save(sensor);
System.out.println(newSensor);
return ResponseEntity.ok("Sensor received");
}
I have tried checking every possible solution and the problem is not fixed, my expectation is the data stored into 1 column for the sensors field in the JSON body.

The problem is with the JPA mapping, not with the Controller, I think.
You're using #Embeddable, which normally result in a set of columns in your main table. If it's a collection of #Embeddable objects, you could map it to a separate table with foreign keys, using #ElementCollection.
However, you want to store the collection of sensors as a single JSON string in a single column in your main table. For that, you do not need the #Embeddable annotation. You need to write a custom convertor to convert the collection of sensors to JSON.
public class SensorsConverter implements AttributeConverter<List<Sensors>, String> {
private final ObjectMapper objectMapper = new ObjectMapper();
#Override
public String convertToDatabaseColumn(List<Sensors> sensors) {
return objectMapper.writeValueAsString(sensors);
}
#Override
public List<Sensors> convertToEntityAttribute(String sensorsJSON) {
return objectMapper.readValue(sensorsJSON, new TypeReference<List<Sensors>>() {});
}
}
Then you can use it in your entity class:
#Column(name = "SENSORS")
#Convert(converter = SensorsConverter.class)
private List<Sensors> sensors;

Using AsyncTask in Activity fails

I have an application in which I wanted to store a list of items and I figured a database would do. I found out about the new Room API and tried using it, though I'm having some trouble getting it working. I have a background service which is supposed to write entries to the database. I read that using the singleton pattern was recomended, but I can't seem to get it working. When I try to retrieve all entries in my MainActivity, the list I get back is always empty, indicating that I wasn't able to save them from the start.
Singleton db class
#Database(entities = {TemperatureReading.class}, version = 1)
public abstract class DatabaseSingleton extends RoomDatabase {
private static DatabaseSingleton INSTANCE;
public abstract TemperatureReadingDao temperatureReadingDao();
public static DatabaseSingleton getAppDatabase(Context context) {
if (INSTANCE == null) {
INSTANCE =
Room.databaseBuilder(context.getApplicationContext(), DatabaseSingleton.class, "fireTempDatabase")
.build();
}
return INSTANCE;
}
public static void destroyInstance() {
INSTANCE = null;
}
}
Entity
#Entity
public class TemperatureReading {
#PrimaryKey(autoGenerate = true)
private int uid;
#ColumnInfo(name = "dateTime")
private long dateTime;
#ColumnInfo(name = "location")
private String readingLocation;
#ColumnInfo(name = "value")
private float value;
public long getDateTime() {
return dateTime;
}
public void setDateTime(long dateTime) {
this.dateTime = dateTime;
}
public String getReadingLocation() {
return readingLocation;
}
public void setReadingLocation(String readingLocation) {
this.readingLocation = readingLocation;
}
public float getValue() {
return value;
}
public void setValue(float value) {
this.value = value;
}
public int getUid() {
return uid;
}
public void setUid(int uid) {
this.uid = uid;
}
}
EntityDAO
#Dao
public interface TemperatureReadingDao {
#Query("SELECT * FROM temperatureReading")
List<TemperatureReading> getAll();
#Query("SELECT * FROM temperatureReading ORDER BY uid desc limit 1")
TemperatureReading getLatest();
#Insert
void insertAll(TemperatureReading... temperatureReading);
#Update
void update(TemperatureReading... temperatureReading);
#Delete
void delete(TemperatureReading temperatureReading);
}
Background service which saves to db
private void saveTempDatabase(float tmpMessageAsFloat, long tmpMessageDateTime) {
Log.d(TAG, "saveTempDatabase");
TemperatureReading tr = new TemperatureReading();
tr.setDateTime(tmpMessageDateTime);
tr.setReadingLocation("XXX"); //TODO
tr.setValue(tmpMessageAsFloat);
DatabaseSingleton.getAppDatabase(getApplicationContext()).temperatureReadingDao().insertAll(tr);
}
MainActivity were db is read from, uses Async task so it doesn't block UI
private void updateTemperature() {
Log.d(TAG, "updateTemperature");
new AsyncTask<Void, Void, Integer>() {
#Override
protected Integer doInBackground(Void... params) {
List<TemperatureReading> tr = DatabaseSingleton.getAppDatabase(MainActivity.this).temperatureReadingDao().getAll(); //List is always empty, no matter how many times I have called the saveTempDatabase() method in the service class.
return 0;
}
#Override
protected void onPostExecute(Integer agentsCount) {
}
}.execute();
}
Maybe it has to do with the context somehow?
EDIT:
Just tried adding .allowMainThreadQueries() when building the database and now it works. So for some reason my Async task isn't working?

Your AsyncTask seems to be wrong. You should return the list you would like to handle in doInBackground and then expect it in onPostExecute. Why do you always return 0?

DynamoDB mapping List of Enum

Mapping an enum class in to DynamoDB object is really simple by using Custom Marshall. But how to map a List of Enum?
Enum class
public enum Transport {
SMS,EMAIL,ALL;
}
DynamoDB mapper
public class Campaign{
private List<Transport> transport;
#DynamoDBAttribute(attributeName = "transport")
public List<Transport> getTransport() {
return transport;
}
public void setTransport(List<Transport> transport) {
this.transport = transport;
}
}

DynamoDBMarshaller is deprecated.
Use DynamoDBTypeConverter instead.
Example:
Enum class
public static enum ValidationFailure {
FRAUD, GENERAL_ERROR
}
DynamoDBTable class
#DynamoDBTable(tableName = "receipt")
public class Receipt {
private Long id;
private List<ValidationFailure> validation;
#DynamoDBHashKey(attributeName = "id")
public Long getId() {
return id;
}
#DynamoDBTypeConverted(converter = ValidationConverter.class)
public List<ValidationFailure> getValidation() {
return validation;
}
public void setId(Long id) {
this.id = id;
}
public void setValidation(List<ValidationFailure> validation) {
this.validation = validation;
}
}
Convertor:
public class ValidationConverter implements DynamoDBTypeConverter<List<String>, List<ValidationFailure>> {
#Override
public List<String> convert(List<ValidationFailure> object) {
List<String> result = new ArrayList<String>();
if (object != null) {
object.stream().forEach(e -> result.add(e.name()));
}
return result;
}
#Override
public List<ValidationFailure> unconvert(List<String> object) {
List<ValidationFailure> result = new ArrayList<ValidationFailure>();
if (object != null) {
object.stream().forEach(e -> result.add(ValidationFailure.valueOf(e)));
}
return result;
}
}

It's working for me, I have used the Set
#DynamoDBTyped(DynamoDBMapperFieldModel.DynamoDBAttributeType.SS)
var roles: MutableSet<Employee.Role>? = null
I think the same approach would work for List with DynamoDBAttributeType.L

I found the answer myself. I create a custom marshall like below.
public class TransportMarshaller implements DynamoDBMarshaller<List<Transport>> {
#Override
public String marshall(List<Transport> transports) {
List<String>transportMap=new ArrayList<>();
for(Transport transport:transports){
transportMap.add(transport.name());
}
return transportMap.toString().replaceAll("\\[|\\]", "");//Save as comma separate value for the purpose of easiness to unmarshall
}
#Override
public List<Transport> unmarshall(Class<List<Transport>> aClass, String s) {
List<String>map= Arrays.asList(s.split("\\s*,\\s*")); //split from comma and parse to List
List<Transport>transports=new ArrayList<>();
for (String st:map){
transports.add(Transport.valueOf(st));
}
return transports;
}
}

How i can design these with abstract class

When i want to add item to favorite .. i write this code my program and access everywhere: Favorite.add(itemid);
When i want to add item to message i write this code my program and access everywhere: Message.add(itemid);
Two class have some methods. So how i can design this useful?
For example;
AbstractData.addFavorite(itemid);
AbstractData.addMessage(itemid);
or
AbstractData<Fav>.add(itemid);
AbstractData<SMS>.add(itemid);
or
Your opinion?
Thank for help and sory for my little english...
Favorite.class
public class Favorite {
static SparseArray<Fav> LIST = new SparseArray<>();
public static boolean add(int ID){
if(!check(ID)){
LIST.put(ID, new Fav(ID, DateFormat.getDateTimeInstance().format(new Date())));
return true;
}
return false;
}
public static void remove(int ID){
if(LIST.indexOfKey(ID) >= 0 )
LIST.remove(ID);
}
public static boolean check(int ID){return LIST.get(ID) != null;}
public static Fav get(int ID){return LIST.get(ID);}
public static void saveALL(){
AsyncTask.execute(new Runnable() {
#Override
public void run() {
Fav favorite;
for (int i = 0; i < LISTE.size(); i++) {
favorite = get(LISTE.keyAt(i));
if (favorite != null)
//Saving data to xml
}
}
});
Log.d("DONE", "Favorite LIST Saving");
}
}
Fav.class
public class Fav implements IModel{
private int ID;
private String DATE;
public Fav(int ID, String DATE) {
this.ID = ID;
this.DATE = DATE;
}
public int getID() {
return ID;
}
public void setID(int ID) {
this.ID = ID;
}
public String getDate() {
return DATE;
}
public void setDate(String DATE) {
this.DATE = DATE;
}
}
Message.class
public class Message{
static SparseArray<SMS> LIST = new SparseArray<>();
public static boolean add(int ID){
if(!check(ID)){
LIST.put(ID, new SMS(ID, DateFormat.getDateTimeInstance().format(new Date())));
return true;
}
return false;
}
public static void remove(int ID){
if(LIST.indexOfKey(ID) >= 0 )
LIST.remove(ID);
}
public static boolean check(int ID){return LIST.get(ID) != null;}
public static SMS get(int ID){return LIST.get(ID);}
public static void saveALL(){
AsyncTask.execute(new Runnable() {
#Override
public void run() {
SMS message;
for (int i = 0; i < LISTE.size(); i++) {
message = get(LISTE.keyAt(i));
if (message != null)
//Saving data to xml
}
}
});
Log.d("DONE", "Message LIST Saving");
}
}
SMS.class
public class SMS implements IModel{
private int ID;
private String DATE;
public SMS(int ID, String DATE) {
this.ID = ID;
this.DATE = DATE;
}
public int getID() {
return ID;
}
public void setID(int ID) {
this.ID = ID;
}
public String getDate() {
return DATE;
}
public void setDate(String DATE) {
this.DATE = DATE;
}
}
IModel.class
public interface IModel {
int getID();
void setID(int ID);
String getDate();
void setDate(String DATE);
}

In my opinion...
Don't over-design your models.
Don't make your add and remove methods static, it will eventually leave you with headaches. You want your constructor to initialize your object.
Either use a Singleton Pattern to get a single instance of your manager object, or
Keep your manager class as a local variable in your Application class, make an access method for it, initialize it in onCreate().
Personally I've started to ditch the getter/setter pattern in favour of public fields, particularly if they're final like in enums. I know this is supposed to be ugly but... I don't care as long as it's convenient =)
So...
public class MyApplication extends Application
{
private static MyApplication instance;
private FavouritesManager favouritesManager;
public static getMyApplicationInstance ()
{
return instance;
}
public void onCreate ()
{
instance = this;
favouritesManager = new FavouritesManager(this); // You may want it to have a Context...
}
}
public class FavouritesManager
{
private Map<Integer,Favourites> favorites;
public FavouritesManager ()
{
load();
}
public void add ( Favourite favourite )
{
favourites.put(favourite.id, favourite);
}
public boolean contains ( int favouriteId )
{
favourites.contaisKey(favouriteId);
}
private void load ()
{
favourites = new HashMap<>();
// Maybe deserialize json from SharedPreferenecs?
}
public List<Favorite> getAll ()
{
// Return all Favourites, sorted by their SortOrder.
}
public Favorite create ( String name )
{
// Maybe a factory method that generates an unused id and returns a new Favourite instance?
}
}
public Favourite
{
public final int id;
public final Date createDate;
public String name;
public int sortOrder;
public Favorite ( int id, String name, int sortOrder )
{
this.id = id;
this.createDate = Date();
this.name = name;
this.sortOrder = sortOrder;
}
}
public class MyActivity extend Activity
{
protected void onCreate ( Bundle savedInstanceState )
{
FavouritesManager favmanager = MyApplication.getMyApplicationInstance().getFavoritesManager();
}
{
}

Make your classes Message and SMS implement the same interface IModel. Then, when you implement your methods (e.g. add()) and want them to accept both Message and SMS objects, use the base interface in your method signature:
public class AbstractData {
public static void add(final IModel data) { // <- Use interface here!
// ...
}
}
Now you can add objects this way:
Message msg = new Message();
AbstractData.add(msg);
SMS sms = new SMS();
AbstractData.add(sms);

Update specific item in arraylist

I want to update specific item in arraylist.
This is Conversation class:
class Conversation
{
String sender,to,name,bio,picture;
Integer id,time,unread;
public Conversation() {
}
public Conversation (int id,String sender,String to,String name,String bio,String picture,int time,int unread) {
this.sender=sender;
this.to=to;
this.id=id;
this.name=name;
this.bio=bio;
this.picture=picture;
this.time=time;
this.unread=unread;
}
public void setSender(String sender) {
this.sender=sender;
}
public void setTo(String to) {
this.to=to;
}
public void setId(int id) {
this.id=id;
}
public void setTime(int time) {
this.time=time;
}
public void setUnread(int unread) {
this.unread=unread;
}
public void setName(String name) {
this.name=name;
}
public void setBio(String bio) {
this.bio=bio;
}
public void setPicture(String picture) {
this.picture=picture;
}
public String getSender() {
return this.sender;
}
public String getTo() {
return this.to;
}
public int getId() {
return this.id;
}
public int getTime() {
return this.time;
}
public int getUnread() {
return this.unread;
}
public String getName() {
return this.name;
}
public String getBio() {
return this.bio;
}
public String getPicture() {
return this.picture;
}
}
I am adding items from database to this list with following lines:
public List<Conversation> getAllConversations() {
List<Conversation> conversationsList=new ArrayList<Conversation>();
String selectQuery = "SELECT * FROM " + TABLE_CONVERSATIONS+" order by id desc";
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
do {
Conversation Conversation = new Conversation();
Conversation.setId(Integer.parseInt(cursor.getString(0)));
Conversation.setSender(cursor.getString(1));
Conversation.setTo(cursor.getString(2));
Conversation.setName(cursor.getString(3));
Conversation.setBio(cursor.getString(4));
Conversation.setPicture(cursor.getString(5));
Conversation.setTime(Integer.parseInt(cursor.getString(6)));
Conversation.setUnread(Integer.parseInt(cursor.getString(7)));
conversationsList.add(Conversation);
} while (cursor.moveToNext());
}
return conversationsList;
}
I want to use setUnread method for specific item but how ? I know I can change like this:
conversationsList.get(location).setUnread(1);
But I don't know the location.I need to get the item with another parameter.e.g can I get the item by sender value ?
I need something like this:
conversationsList.getByUsername("username").setUnread(1);

An ArrayList can only be accessed by using a zero-based index. If you want to acces the elements by using another key (id or username) you need to use a Map or SparseArray (if you use a numeric key).
Since you wanted to lookup elements by "username", I'll use a map in the following example:
public Map<String, Conversation> getAllConversations() {
final Map<String, Conversation> conversations = new HashMap<>();
Cursor cursor = ...;
while (cursor.moveToNext()) {
Conversation conversation = new Conversation();
...
conversations.put(conversation.getSender(), conversation);
}
cursor.close(); // don't forget to close your cursors!
return conversations;
}
Then you can look up conversations like this:
conversations.get("John Doe").setUnread(1);
Note: You can use conversation.setTime(cursor.getInt(6)); instead of conversation.setTime(Integer.parseInt(cursor.getString(6)));. The SQLite database does not really care whether you store a string or an integer.