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DynamoDB - how to get Primary Key (which is random id) from database to make endpoind class?

I've made method that I use to edit Item from database.
This is how my method looks:
public Product editProduct(PrimaryKey primaryKey, Product content) {
UpdateItemSpec updateItemSpec = new UpdateItemSpec().withPrimaryKey(primaryKey).withValueMap(createValueMap(content));
UpdateItemOutcome itemOutcome = databaseController.getTable(PRODUCT_TABLE).updateItem(updateItemSpec);
return convertToProduct(itemOutcome);
}
private Map<String, Object> createValueMap(Product content) {
Map<String, Object> result = new HashMap<>();
result.put("name", content.getName());
result.put("calories", content.getCalories());
result.put("fat", content.getFat());
result.put("carbo", content.getCarbo());
result.put("protein", content.getProtein());
result.put("productKinds", content.getProductKinds());
result.put("author", content.getAuthor());
result.put("media", content.getMedia());
result.put("approved", content.getApproved());
return result;
}
private Product convertToProduct(UpdateItemOutcome itemOutcome) {
Product product = new Product();
product.setName(itemOutcome.getItem().get("name").toString());
product.setCalories(itemOutcome.getItem().getInt("calories"));
product.setFat(itemOutcome.getItem().getDouble("fat"));
product.setCarbo(itemOutcome.getItem().getDouble("carbo"));
product.setProtein(itemOutcome.getItem().getDouble("protein"));
product.setProductKinds(itemOutcome.getItem().getList("productKinds"));
ObjectMapper objectMapper = new ObjectMapper();
try {
Author productAuthor = objectMapper.readValue(itemOutcome.getItem().getString("author"), Author.class);
product.setAuthor(productAuthor);
} catch (IOException e) {
e.printStackTrace();
}
try {
Media productMedia = objectMapper.readValue(itemOutcome.getItem().getString("media"), Media.class);
product.setMedia(productMedia);
} catch (IOException e) {
e.printStackTrace();
}
return product;
}
Now I want to create endpoint class for this method but I have problem, I need to get primarykey as parameter (it's looks like this for example: 2567763a-d21e-4146-8d61-9d52c2561fc0) and I don't know how to do this.
At the moment my class looks like that:
public class EditProductLambda implements RequestHandler<Map<String, Object>, ApiGatewayResponse> {
private LambdaLogger logger;
#Override
public ApiGatewayResponse handleRequest(Map<String, Object> input, Context context) {
logger = context.getLogger();
logger.log(input.toString());
try{
Product product = RequestUtil.parseRequest(input, Product.class);
//PrimaryKey primaryKey = XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
KitchenService kitchenService = new KitchenService(new DatabaseController(context, Regions.EU_CENTRAL_1), logger);
Product editedProduct = kitchenService.editProduct(primaryKey, product);
return ResponseUtil.generateResponse(HttpStatus.SC_CREATED, editedProduct);
} catch (IllegalArgumentException e){
return ResponseUtil.generateResponse(HttpStatus.SC_BAD_REQUEST, e.getMessage());
}
}
Can someone give me some advice how to do that? Or maybe my method is done wrong?

So first you have to create a trigger to Lambda function and ideal prefer here would be an API gateway. You can pass your data as query string or as a request body to API gateway.
You can use body mapping template in the integration request section of API gateway and get request body/query string. Construct a new json at body mapping template, which will have data from request body/query string. As we are adding body mapping template your business logic will get the json we have constructed at body mapping template.
Inside body mapping template to get query string please do ,
$input.params('querystringkey')
For example inside body mapping template (If using query string),
#set($inputRoot = $input.path('$'))
{
"primaryKey" : "$input.params('$.primaryKey')"
}
if passing data as body then,
#set($inputRoot = $input.path('$'))
{
"primaryKey" : "$input.path('$.primaryKey')"
}
Please read https://aws.amazon.com/blogs/compute/tag/mapping-templates/ for more details on body mapping template

Issue converting from JSON to POJO using Gson

I have a JSON REST endpoint response and I wanted to get the value of hotelNbr from it. How do i do it ?
{
"found": [
{
"hotelNbr": 554050442,
"hotelAddress": "119 Maven Lane, New Jersey",
}
],
"errors": []
}
I am using the below code to get it but it fails in below mentioned line:
public List<Hotel> RDS_POST_HotelDetails(String HotelName, String sUrl) throws Exception, IOException {
Gson gson = new GsonBuilder().setPrettyPrinting().create();
// Create your http client
CloseableHttpClient httpclient = HttpClientBuilder.create().build();
// Create http Put object
HttpPost ohttppost = new HttpPost(sUrl);
// Message Body
StringEntity input = new StringEntity(
"{\"hotelNbr\":[\""+HotelName+"\" ]}"
);
// Set content type for post
input.setContentType("application/json");
// attach message body to request
ohttppost.setEntity(input);
// submit request and save response
HttpResponse response = httpclient.execute(ohttppost);
// Get response body (entity and parse to string
String sEntity = EntityUtils.toString(response.getEntity());
List<Hotel> hotelobject = new ArrayList<Hotel>();
// Create a type token representing the type of objects in your json response
// I had to use the full class path of TYPE because we also have a Type class in our project
java.lang.reflect.Type cType = new TypeToken<List<Hotel>>() {
}.getType();
// Convert to Array object using gson.fromJson(<json string>,
// <type>)
hotelObject = gson.fromJson(sEntity, cType); // I am getting error here
String hotelNumber = hotelObject.get(0).getFound().get(0).getItemNbr().toString();
}
Please find the Hotel.java class below
package com.hotels.company;
import java.util.List;
import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;
public class Hotel {
#SerializedName("found")
#Expose
private List<Found> found = null;
#SerializedName("errors")
#Expose
private List<Object> errors = null;
public List<Found> getFound() {
return found;
}
public void setFound(List<Found> found) {
this.found = found;
}
public List<Object> getErrors() {
return errors;
}
public void setErrors(List<Object> errors) {
this.errors = errors;
}
}
Please find Found.java class below :
package com.hotels.company;
import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;
public class Found {
#SerializedName("hotelNbr")
#Expose
private Integer hotelNbr;
#SerializedName("hotelAddress")
#Expose
private String hotelAddress;
public Integer getHotelNbr() {
return hotelNbr;
}
public void setHotelNbr(Integer hotelNbr) {
this.hotelNbr = hotelNbr;
}
public String getHotelAddress() {
return hotelAddress;
}
public void setHotelAddress(String hotelAddress) {
this.hotelAddress = hotelAddress;
}
}
I tried finding some examples in StackOverflow questions but didn't get solution for mine. Any help will be appreciated.

The JSON you are parsing is not well formatted..
There is a comma after "hotelAddress" remove that
Correct JSON would be:
{
"found":[
{
"hotelNbr":554050442,
"hotelAddress":"119 Maven Lane, New Jersey"
}
],
"errors":[ ]
}

I found a couple of issues:
Json is not valid. Observe there is a comma at the end of "hotelAddress": "119 Maven Lane, New Jersey",. Remove it.
You are trying to deserialize the json into List<Hotel>, but the json mentioned is not a list. Either update the json or deserialise it into Hotel object instead of List.

Firebase Android: how do I access params nested in data via RemoteMessage?

via this shape:
{
"to": "000",
"priority": "high",
"data": {
"title": "A Title",
"message": "A Message",
"link": {
"url": "http://www.espn.com",
"text": "ESPN",
}
}
}
how can I access "url" and "text"?
String messageLink = remoteMessage.getData().get("link");
gets me:
{"text":"ESPN","url":"http://www.espn.com"}
but how do I drill deeper?
remoteMessage.getData().get("link").get("text");
doesnt quite work... I have also attempted JSONObject:
JSONObject json = new JSONObject(remoteMessage.getData());
JSONObject link = json.getJSONObject("link");
but this gives me try catch errors...
Any help and direction as always is greatly appreciated!

I would use gson and define a model class. The remote message gives you a Map<String, String> and their is no matching constructor for creating a json object.
Add gson to your build.xml:
compile 'com.google.code.gson:gson:2.5'
Create a notification model:
import com.google.gson.annotations.SerializedName;
public class Notification {
#SerializedName("title")
String title;
#SerializedName("message")
String message;
#SerializedName("link")
private Link link;
public String getTitle() {
return title;
}
public String getMessage() {
return message;
}
public Link getLink() {
return link;
}
public class Link {
#SerializedName("url")
String url;
#SerializedName("text")
String text;
public String getUrl() {
return url;
}
public String getText() {
return text;
}
}
}
Deserialize a notification object from the remote message.
If all your custom keys are at the top level:
Notification notification = gson.fromJson(gson.toJson(remoteMessage.getData()), Notification.class);
If your custom json data is nested in a single key for example "data" then use:
Notification notification = gson.fromJson(remoteMessage.getData().get("data"), Notification.class);
Note in this simple case the #SerializedName() annotations are unnecessary since the field names exactly match the keys in the json, but if you for example have a key name start_time but you want to name the java field startTime you would need the annotation.

As simple as that:
String linkData = remoteMessage.getData().get("link");
JSONObject linkObject = new JSONObject(linkData);
String url = linkObject.getString("url");
String text = linkObject.getString("text");
Of course, together with proper error handling.

Faced this issue when migrating from GCM to FCM.
The following is working for my use case, so perhaps it will work for you.
JsonObject jsonObject = new JsonObject(); // com.google.gson.JsonObject
JsonParser jsonParser = new JsonParser(); // com.google.gson.JsonParser
Map<String, String> map = remoteMessage.getData();
String val;
for (String key : map.keySet()) {
val = map.get(key);
try {
jsonObject.add(key, jsonParser.parse(val));
} catch (Exception e) {
jsonObject.addProperty(key, val);
}
}
// Now you can traverse jsonObject, or use to populate a custom object:
// MyObj o = new Gson().fromJson(jsonObject, MyObj.class)

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;
}

How to read JSON-c data from Youtube API using GSON in Android Apps

First, im a beginner in JSON and GSON, so please bear with me.
I want to read the data that i retrieved from this link :
https://gdata.youtube.com/feeds/api/videos?author=radityadika&v=2&alt=jsonc
So i tried to create some classes that represent the result of the link above :
Video.java
public class Video implements Serializable {
// The title of the video
#SerializedName("title")
private String title;
// A link to the video on youtube
#SerializedName("url")
private String url;
// A link to a still image of the youtube video
#SerializedName("thumbUrl")
private String thumbUrl;
#SerializedName("id")
private String id;
public Video(String id, String title, String url, String thumbUrl) {
super();
this.id = id;
this.title = title;
this.url = url;
this.thumbUrl = thumbUrl;
}
/**
* #return the title of the video
*/
public String getTitle(){
return title;
}
/**
* #return the url to this video on youtube
*/
public String getUrl() {
return url;
}
/**
* #return the thumbUrl of a still image representation of this video
*/
public String getThumbUrl() {
return thumbUrl;
}
public String getId() {
return id;
}
}
Library.java
public class Library implements Serializable{
// The username of the owner of the library
#SerializedName("user")
private String user;
// A list of videos that the user owns
private List<Video> videos;
public Library(String user, List<Video> videos) {
this.user = user;
this.videos = videos;
}
/**
* #return the user name
*/
public String getUser() {
return user;
}
/**
* #return the videos
*/
public List<Video> getVideos() {
return videos;
}
}
After that, i tried to retrieve the data using those code :
#Override
public void run() {
try {
// Get a httpclient to talk to the internet
HttpClient client = new DefaultHttpClient();
// Perform a GET request to YouTube for a JSON list of all the videos by a specific user
HttpUriRequest request = new HttpGet("https://gdata.youtube.com/feeds/api/videos?author="+username+"&v=2&alt=jsonc");
//HttpUriRequest request = new HttpGet("https://gdata.youtube.com/feeds/api/videos?title="+username+"&v=2&alt=jsonc");
// Get the response that YouTube sends back
HttpResponse response = client.execute(request);
// Convert this response into a readable string
//String jsonString = StreamUtils.convertToString(response.getEntity().getContent());
final int statusCode = response.getStatusLine().getStatusCode();
if (statusCode != HttpStatus.SC_OK) {
//Log.w(getClass().getSimpleName(), "Error " + statusCode);
}
// Create a JSON object that we can use from the String
//JSONObject json = new JSONObject(jsonString);
HttpEntity getResponseEntity = response.getEntity();
InputStream httpResponseStream = getResponseEntity.getContent();
Reader inputStreamReader = new InputStreamReader(httpResponseStream);
Gson gson = new Gson();
this.library = gson.fromJson(inputStreamReader, Library.class);
} catch (Exception e) {
Log.e("Feck", e);
}
}
However i cant retrieve the data. The this.library variable, which is an instance of Library Class always null.
Any help is appreciated, and please ask me if you need more code.
Thanks very much

OK, I can understand you do not have any idea about JSON and Gson... but have you taken at least a quick look to JSON specifications or Gson documentation?
After reading just a little while, I suggest you to use this handy online JSON Viewer to view the JSON data you're retrieving in a user-friendly way. You just need to copy the whole JSON in the Text tab and click the Viewer tab...
If you do that, you'll see the structure of your JSON, which is something like this:
{
...
"data": {
...
"items": [
{
"id": "someid",
"title": "sometitle",
...
},
...
]
}
}
Now, what you have to do is to create a Java class structure that represents the data structure of your JSON, and you are not doing it! Why did you add the attributes user and videos to your Library class? Did you think that Gson can magically understand that you want to retrieve the user and his videos? It doesn't really work like that......
In order to create the suitable class structure, start by doing something like this (in pseudo-code):
class Response
Data data;
class Data
List<Item> items;
class Item
String id;
String title;
Because as you may have realized by now, this class structure does represent your JSON data! Then just add more classes and attributes depending on what data you want to retrieve (add only those classes and attributes you need to retrieve, the rest will be automatically skipped).