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Write custom document to Cosmos DB with Java API

I have a Cosmos DB and want to write different kind of documents to it. The structure of the documents is dynamic and can change.
I tried the following. Let's say I have the following class:
class CosmosDbItem implements Serializable {
private final String _id;
private final String _payload;
public CosmosDbItem(String id, String payload) {
_id = id;
_payload = payload;
}
public String getId() {
return _id;
}
public String getPayload() {
return _payload;
}
}
I can create then the document with some JSON as follows:
CosmosContainer _container = ...
CosmosDbItem dataToWrite = new CosmosDbItem("what-ever-id-18357", "{\"name\":\"Jane Doe\", \"age\":42}")
item = _cosmosContainer.createItem(dataToWrite, partitionKey, cosmosItemRequestOptions);
This results in a document like that:
{
"id": "what-ever-id-18357",
"payload": "{\"name\":\"Jane Doe\", \"age\":42}",
"_rid": "aaaaaaDaaAAAAAAAAAA==",
"_self": "dbs/aaaaAA==/colls/aaaaAaaaDI=/docs/aaaaapaaaaaAAAAAAAAAA==/",
"_etag": "\"6e00c443-0000-0700-0000-5f8499a70000\"",
"_attachments": "attachments/",
"_ts": 1602525607
}
Is there a way in generating the payload as real JSON object in that document? What do I need to change in my CosmosDbItem class? Like this:
{
"id": "what-ever-id-18357",
"payload": {
"name":"Jane Doe",
"age":42
},
"_rid": "aaaaaaDaaAAAAAAAAAA==",
"_self": "dbs/aaaaAA==/colls/aaaaAaaaDI=/docs/aaaaapaaaaaAAAAAAAAAA==/",
"_etag": "\"6e00c443-0000-0700-0000-5f8499a70000\"",
"_attachments": "attachments/",
"_ts": 1602525607
}

Here is my solution that I ended up. Actually it is pretty simple once I got behind it. Instead of using CosmosDbItem I use a simple HashMap<String, Object>.
public void writeData() {
...
Map<String, Object> stringObjectMap = buildDocumentMap("the-id-", "{\"key\":\"vale\"}");
_cosmosContainer.createItem(stringObjectMap, partitionKey, cosmosItemRequestOptions);
...
}
public Map<String, Object> buildDocumentMap(String id, String jsonToUse) {
JSONObject jsonObject = new JSONObject(jsonToUse);
jsonObject.put("id", id);
return jsonObject.toMap();
}
This can produce the following document:
{
"key": "value",
"id": "the-id-",
"_rid": "eaaaaaaaaaaaAAAAAAAAAA==",
"_self": "dbs/eaaaAA==/colls/eaaaaaaaaaM=/docs/eaaaaaaaaaaaaaAAAAAAAA==/",
"_etag": "\"3b0063ea-0000-0700-0000-5f804b3d0000\"",
"_attachments": "attachments/",
"_ts": 1602243389
}
One remark: it is important to set the id key in the HashMap. Otherwise one will get the error
"The input content is invalid because the required properties - 'id; ' - are missing"

Parse JSON response with numbers as Object

I have this JSON response, from a remote server and i really hope i can get help.
{
"data": {
"6111": {
"prereq": "0",
"mast": "The Master Tree"
},
"6112": {
"prereq": "1",
"mast": "Another Master Tree"
}
}
}
I use GSON to parse JSON, using the #SerializedName and #Exposeto obtain the value into a custom Model. But i do not understand how to get past the
"6111"
"6112"
I have checked other questions via the gson tag, to no avail.

try this
Iterator<String> iter = json.keys();
while (iter.hasNext()) {
String key = iter.next();
try {
Object value = json.get(key);
} catch (JSONException e) {
// Something went wrong!
}
}
///////////////////update////////////////////
JSONObject issueObj = new JSONObject(jsonContent);
Iterator iterator = issueObj.keys();
while(iterator.hasNext()){
String key = (String)iterator.next();
JSONObject issue = issueObj.getJSONObject(key);
// get id from issue
String _pubKey = issue.optString("id");
}

If you're using Gson, any time you have an object with keys you don't know ahead of time, you can just use Map instead of a custom object.
In this case, each element of the Map will be some "known" data structure, so you would use Map<String, MyObject>.
Your top-level class:
public class MyResponse {
#SerializedName("data")
#Expose
private Map<String, MyObject> data;
...
}
And your map's value class:
public class MyObject {
#SerializedName("prereq")
#Expose
private String prereq;
#SerializedName("mast")
#Expose
private String mast;
...
}
In the specific case of the json text you posted, you would then be able to use these objects like this:
response.getData().get("6111").getMast();
But you can also do anything you could normally do with a Map:
Map<String, MyObject> data = response.getData();
for (String key: data.keySet() {
...
}
for (MyObject obj : data.values()) {
...
}

return any exception in json in rest api

Is there any simple methods to return exception in JSON using Rest api?
I've already googled this question, but all solutions i see, was about throwing exceptions during some calculations. But what if income parameters are wrong? I mean what if there is sone string instead of int input parameter?
I created some DTO class for input data:
#XmlRootElement
public class RequestDTO implements Serializable{
private static final long serialVersionUID = 1L;
#XmlElement(name = "request_id")
private String requestId;
#XmlElement(name = "site")
private List<String> sitesIds;
#XmlElement(name = "date_begin")
#JsonSerialize(using = DateSerializer.class)
#JsonDeserialize(using = DateDeserializer.class)
private Date dateBegin;
#XmlElement(name = "date_end")
#JsonSerialize(using = JsonDateSerializer.class)
#JsonDeserialize(using = JsonDateDeserializer.class)
private Date dateEnd;
#XmlElement(name = "volume")
private double volume;
// there is getters and setters
}
If i sent something like 'qwerty' instead of 'volume' field in my json request i'l see error message like Runtime. Is it possible to handle it in someway? I mean to return error in json with such structure?
public class ExceptionDTO {
private String shortExceptionMessage;
private String stackTrace;
public ExceptionDTO(String shotExceptionMessage, String stackTrace){
this.shortExceptionMessage = shotExceptionMessage;
this.stackTrace = stackTrace;
}
public String getShortExceptionMessage() {
return shortExceptionMessage;
}
public String getStackTrace() {
return stackTrace;
}
}
UPD1:
#Provider
#Singleton
public class ExceptionMapperProvider implements ExceptionMapper<Exception>{
#Override
public Response toResponse(final Exception e) {
StringBuilder trace = new StringBuilder();
IntStream.range(0, e.getStackTrace().length)
.forEach(i -> trace.append(e.getStackTrace()[i]).append('\n'));
ExceptionDTO exceptionMessage = new ExceptionDTO(
e.toString(),
trace.toString()
);
return Response.status(500).entity(exceptionMessage).build();
}
}

As it's not really clear if you are interested on checking if field or value of the payload is correct, here are a few ways to work with both.
If you want to check if the value for a field is correct (ie volume field value should be greater than zero etc), check out bean validation. This makes use of annotations on the fields you want to verify.
// for example
#Min(value = 0, message = "invalid message")
private double range;
To use your ExceptionDTO as error response whenever one of those validation fails, you can do so by creating an ExceptionMapper<ConstraintViolationException>. check it here for more details.
If you are checking for the invalid field (ie client sends ragne fields instead of range), have a look at the stack trace on what exception is being thrown. Then register an exception mapper with your ExceptionDTO as body.
For example, if UnrecognizedPropertyException is thrown then you can add:
#Provider
public class UnrecognizedPropertyExceptionMapper implements ExceptionMapper<UnrecognizedPropertyException> {
#Override
public Response toResponse(UnrecognizedPropertyException e) {
ExceptionDTO myDTO = // build response
return Response.status(BAD_REQUEST).entity(myDTO).build();
}
}

If you want to validate input parameters in the request, you should return status code 400 (Bad Request) along with the error details. You can simply send json
{ "error": { "message": "string received for parameter x, where as int expected" } with the response status code 400.
`

I did a bit of research and determined that the best way to encode a Java exception in JSON is to use a convention developed by Oasis that looks like this:
{
"error": {
"code": "400",
"message": "main error message here",
"target": "approx what the error came from",
"details": [
{
"code": "23-098a",
"message": "Disk drive has frozen up again. It needs to be replaced",
"target": "not sure what the target is"
}
],
"innererror": {
"trace": [ ... ],
"context": [ ... ]
}
}
}
details is a list that should have an entry for each nested cause exception in the chain.
innererror.trace should include the stack trace if you wish, as a list of string values.
The response status code should be 400 unless you have a good reason for making it something else, and the code in the structure should match whatever you sent.
Write one method to convert a Java exception to this format, and you are done. Use it consistently and your JS code will be able to handle and display the exception values.
More of the details of the other approaches evaluated and dismissed are covered in this blog post on JSON REST API – Exception Handling
https://agiletribe.purplehillsbooks.com/2015/09/16/json-rest-api-exception-handling/
Here is the java method to convert an exception to this format:
public static JSONObject convertToJSON(Exception e, String context) throws Exception {
JSONObject responseBody = new JSONObject();
JSONObject errorTag = new JSONObject();
responseBody.put("error", errorTag);
errorTag.put("code", 400);
errorTag.put("target", context);
JSONArray detailList = new JSONArray();
errorTag.put("details", detailList);
String lastMessage = "";
Throwable runner = e;
while (runner!=null) {
String className = runner.getClass().getName();
String msg = runner.toString();
runner = runner.getCause();
JSONObject detailObj = new JSONObject();
detailObj.put("message",msg);
int dotPos = className.lastIndexOf(".");
if (dotPos>0) {
className = className.substring(dotPos+1);
}
detailObj.put("code",className);
System.out.println(" ERR: "+msg);
detailList.put(detailObj);
}
JSONObject innerError = new JSONObject();
errorTag.put("innerError", innerError);
JSONArray stackList = new JSONArray();
runner = e;
while (runner != null) {
for (StackTraceElement ste : runner.getStackTrace()) {
String line = ste.getFileName() + ":" + ste.getMethodName() + ":" + ste.getLineNumber();
stackList.put(line);
}
stackList.put("----------------");
runner = runner.getCause();
}
errorTag.put("stack", stackList);
return responseBody;
}

Jackson double serialized json string to Java object

I have a Json string which has a string message field.
String:
{ "Type" : "Text",
"Subject" : "data received",
"Message" :"{\\"language\\":\\"US\\",\\"data\\":\\"signature\\"}"
}
I want to convert it into the following structure:
Notification.java
public class Notification {
String type;
String subject;
Message message;
}
Message.java
public class Message {
String language;
String data;
}
Is there a way in which I can directly convert the string to a Java object of the above structure? I want to avoid deserializing twice.

You can create a custom Deserializer to deserialize the Message text into Message object and annotate the Message class with #JsonDeserialize:
#JsonDeserialize(using = MessageDeserializer.class)
public class Message {
String language;
String data;
}
public class MessageDeserializer extends JsonDeserializer<Message> {
public MessageDeserializer() {
super();
}
#Override
public Message deserialize(
final JsonParser jsonParser, final DeserializationContext deserializationContext) throws
IOException, JsonProcessingException {
final String messageText = jsonParser.getText();
// parse messageText into Message object
}
}

I am not sure my solution is acceptable since it does require additional explicit call to ObjectMapper to perform deserialization of the string value of Message.
However, this is it is done during the buildup of Notification object and does not require a String message property.
You need to add a ctor with String argument to Message class, where you can deserialize the String into Map and extract the instance propertieds:
public Message(String str) {
try {
#SuppressWarnings("unchecked")
Map<String, Object> map =
(Map<String, Object>)new ObjectMapper().readValue(str, Map.class);
language = map.containsKey("language") ? map.get("language").toString() : null ;
data = map.containsKey("data") ? map.get("data").toString() : null ;
} catch (Exception e) {
e.printStackTrace();
}
}
the new ctor will be called by Jackson when you deserialize a Notification object:
Notification n = (Notification)new ObjectMapper().readValue(reader, Notification.class);

You can convert json string into key-value pairs in Map.You will have to do twice as the Message value is again a json string.Use org.json for JSONObject
Map<String, String> map = new HashMap<String, String>();
JSONObject j = new JSONObject(str);
Iterator<String> keys = j.keys();
while( keys.hasNext() ){
String key = (String)keys.next();
String val = j.getString(key);
map.put(key, val);}
Then retrieve the values by iterating over the keys and pass the values into the class constructor
Then map.get(key) can be used to retrieve the values and will be passed into constructors of the classes.

The org.json library is easy to use:
//Create Json object to parse string
// str is input string
JSONObject obj = new JSONObject(str);
//Create Message
Message mess = new Message();
JSONObject obj2 = new JSONObject(obj.getString("Message"));
mess.data = obj2.getString("data");
mess.language = obj2.getString("language");
//Create Notification
Notification noti = new Notification();
noti.message = mess;
noti.subject = obj.getString("Subject");
noti.type = obj.getString("Type");

Gson decode json

I am using PHP to generate Json that was grabbed from a database query. The result looks like this:
[
{
"title":"Title 1",
"description":"This is description 1",
"add_date":"2013-07-17 10:07:53"
},{
"title":"Title 2",
"description":"This is description 2",
"add_date":"2013-07-17 10:07:53"
}
]
I am using Gson to parse the data, like this:
public class Search{
public Search(String text){
try{
// Snipped (gets the data from the website)
Gson json = new Gson();
Map<String, Event> events = json.fromJson(resultstring, new TypeToken<Map<String, Event>>(){}.getType());
System.out.print(events.get("description"));
}catch(IOException ex){
Logger.getLogger(Search.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
class Event {
private String description;
}
here is the message I am getting while trying to run the code:
Exception in thread "AWT-EventQueue-0" com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 3
How would I loop through each one to get the value of description, or title or both?

Several corrections on what you are doing and you should be good to go:
class Event {
private String description;
private String title;
#SerializedName("add_date") private String addDate;
public getDescription() {
return description;
}
}
public Search(String text){
try{
// Snipped (gets the data from the website)
Gson json = new Gson();
Event[] events = json.fromJson(resultstring, Event[].class);
System.out.print(events[0].getDescription());
}catch(IOException ex){
Logger.getLogger(Search.class.getName()).log(Level.SEVERE, null, ex);
}
}
I have corrected your bean class and changed the type of what you convert to (array of Event, because this is what you actually are getting from the PHP service);