I have a Java-written Web API wherein I have web controllers handling HTTP requests. I'm trying to implement a RESTful architecture with HATEOAS, using Spring Boot. When adding HATEOAS links in methods I can easily add links for GET/DELETE requests, but I'm having trouble with POST/PUT/PATCH requests, mostly because those require me to supply a body of the thing I want to post, usually in JSON format. I've been googling for a while and I can't find out how to do it.
Here's how I'm adding links to GET / DELETE operations.
/**
* Shows all the Rooms present in the database.
*
* #return OK status and a list of Room Minimal DTO.
*/
#GetMapping(path = "/", produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<Object> getRooms() {
List<RoomDTOMinimal> roomDTOList = roomRepository.getAllDTOWebInformation();
for (RoomDTOMinimal r : roomDTOList) {
if (userService.getUsernameFromToken().equals("ADMIN")) {
Link roomSensors = linkTo(methodOn(RoomsWebController.class).getSensors(r.getName())).withRel("Get Room" +
"Sensors");
Link deleteRoom = linkTo(methodOn(RoomsWebController.class).deleteRoom(r)).withRel("Delete this Room");
r.add(roomSensors);
r.add(deleteRoom);
} else if (userService.getUsernameFromToken().equals("REGULAR_USER")) {
Link roomTemp = linkTo(methodOn(RoomsWebController.class).getCurrentRoomTemperature(r.getName())).
withRel("Get Room Temperature");
r.add(roomTemp);
}
}
return new ResponseEntity<>(roomDTOList, HttpStatus.OK);
}
I want to add a Link to an "editRoom" request, something like:
Link editRoom = linkTo(methodOn(RoomsWebController.class).configureRoom(r.getName(), WHAT GOES HERE???).withSelfRel();
But configureRoom takes in the roomName and a roomDTO in its signature. RoomDTO is a #RequestBody, so I can't give it to the Link. How should I add the link to the objects in a way that then allows me to call on that method?
I'd like to have something like:
ROOM | Delete | Edit
On the client side, where if I click DELETE the room is deleted, and if I click Edit the client side expands, with text boxes, allowing me to insert the required parameters to edit the room. I have the client-side code implemented for the Edit function, with appropriate front-end; but I can't link to it on the server-side without already providing data that should come later, from the user input. What's the best way to do this?
I've since solved it after talking with a team lead. Apparently it's acceptable to either pass null or an empty DTO object as a parameter in the scenario above; the HATEOAS implementation cares specifically about those parameters that are of the path, and roughly speaking ignores the others. Those can then be replaced as needed on the client-side upon a user performing an action / inserting input.
Related
I've created my first Play Framework Website with Java using the official documentation. It has a single page where I display a list of items that can be filtered or modified.
I have a Controller class with a method:
public CompletionStage<Result> feedpostslist(String domain, String date, String state, int page, int resnum, String search) {
return feedRepository.getArticleList(domain, date, state, page, resnum, search).thenApplyAsync(articles -> {
FeedArticle[] list = new FeedArticle[articles.size()];
articles.toArray(list);
return ok(views.html.feedpostslist.render(list));
}, ec.current());
}
This method does a query to the DB (through feedRepository) and then display the result using the view feedpostslist.
Everything is fine but now I need to get other data from the DB to be used in the same web page (so multiple queries). How do I do this in Play Framework? I don't understand what is the best way to do that.
Should I do multiple DB request inside the method showed before (through feedRepository) and then pass all these informations to my view? I don't want to do a mess or even something too heavy to handle.
If the second query doesn't depend on the first one you can run them in parallel using combineAsync. This is a good example on how to do that:
https://github.com/playframework/play-samples/blob/2.8.x/play-java-ebean-example/app/controllers/HomeController.java#L85
If the second query depends on results on the first then there's nothing you can do but to wait for the first one to complete and run the second one.
Sometimes I will want to pass in an identifier to my website through the url, but I don't want to display this to the user. Is there a simple way to take in a request param but not display it to the user when loading the page?
This is a general idea of how my code is set up currently
#GetMapping("/somePage")
public ModelAndView get(#RequestHeader HttpHeaders headers,
#RequestParam(value = "someId", required = false) String someId) {
I know I could theoretically do this on the javascript side, but that seems to require the page to reload or mess with the history.
Generally this is bad practice - if it's passed in the URL, it'll be visible in the user's browser history. POST is probably the best practice here.
But to answer your actual question:
Put your custom value into a header and redirect?
Something along these lines (untested)
headers.set("X-Custom-Header1", someId);
headers.set("Location", "/newEndpoint");
return new ResponseEntity<>(headers, HttpStatus.FOUND);
I'm using the following approach to return a Facebook user's music preferences:
//FIXME: Fetch results in a single operation
val likes = facebook.likeOperations().music
val artists = ArrayList<Artist>()
for (musicLiked in likes)
{
val musicProfile = facebook.fetchObject(musicLiked.id, Page::class.java, "id", "name", "genre");
artists.add(Artist(name = musicProfile.name, genre = musicProfile.genre))
}
The above approach won't scale, since we have an additional network operation for each artist the user likes.
I tried:
I tried using facebook.likeOperations.music however this doesn't fetch genre.
Question:
I would like to use facebook.fetchObject with a query that returns a PagedList. How to do this?
(No need to post example code in Kotlin if you prefer or are more familiar with Java - I'll be happy with information in any language).
Facebook api uses "fields" parameter in requests to return custom fields for objects. This parameter can be also used for liked music rest request.
me/music?fields=id,genre,name
above link will return all liked music with id, genre and name of the artist/group. Unfortunately FacebookTemplate does not have method which will apply for your needs. The method Facebook.likeOperations() returns instance of the LikeTemplate class which has constant PAGE_FIELDS with value
private static final String PAGE_FIELDS = "id,name,category,description,location,website,picture,phone,affiliation,company_overview,likes,checkins";
In above constant you do not have genre field. So you have two ways:
You can simply use facebook rest api with some rest library
You can override FacebookTemplate and return your own implementation of LikeTemplate as result of the likeOperations() method. You implementation of the LikeTemplate class should have different value in mentioned constant (added genre field at the end of the string)
Maybe some one will be more helpful but in my knowledge you do not have other options.
Thanks to advice given in #burovmarley's answer, I inspected the source and came up with:
val music = facebook.fetchConnections(userPage.id, "music", Page::class.java,
PagingParameters(25, 0, null, null).toMap(), "id,name,,genre")
for (musicLiked in music)
{
println("likes: ${musicLiked.name}, genre: ${musicLiked.genre}")
}
This allows using Spring Social Facebook as an unmodified dependency, and without issuing a pull request, which seem to be fairly slow in processing through the queue at the present time.
Good evening,
I have a form on a JSP page that's connected to a servlet, that form has some dynamic parts using JavaScript like adding a row to a table or adding a text field based on the selected option on a select element, Actually my problem is that I have some validations on the servlet-side, so when I go to servlet to check the (National ID) for example if there's any problem or any violations to my validation I force to get back to the form using :
if (dbm.MatchIdNumber(Candidate.getRegNumber(), Candidate.getNationalID()) == false) {
out.println("<script>\n"
+ " alert('Your National Id does not match your Registration Number');\n"
+ "</script>");
out.println("<script>\n"
+ " window.history.go(-1);\n"
+ "</script>");
}
What happens is when I get back to the form I lose all the JavaScript changes, Which's very important.
I've been reading for a while that using ajax might be the optimal solution for me, but here is my questions:
Is there a way to call a java method from JavaScript or JQuery before getting to servlet without using ajax !?!
Is there a way to get back from the servlet to the jsp page with the ability to keep all the JavaScript Chages !?
If not !!, How to use ajax in my case ?!
Thank you so much
No. JavaScript runs on the user's browser and your Java code runs on your webserver, so basically the only way to communicate between the two is via HTTP requests.
If you don't want to use AJAX, you could provide all of the relevant info when you submit the form to the server for validation. You could pass all the info you need to re-generate the form as it was, like which new fields are there and such
First, you'll need to add a new webservice to your Java webapp which performs validation. To achieve this, you could either add additional logic to your servlet (so that it looks for a request parameter like "doValidation=1" and performs validation if it's there) or write a different servlet that handles validation itself. You'll need to decide the format it should expect the form data in and how it should return the validation information.
On your frontend page, you'll need to modify the behavior of the form so that, when you need to do validation, it performs a request to this webservice and passes along the form data. I would probably do this with jQuery and do something like jQuery.ajax(...) and pass the contents of the form as a JSON object.
When your validation servlet returns data from the ajax call, you'll need to update the form based on the data it provides. If I was doing it, I would probably just have the servlet return a JSON object like {errorMessage:"..."} and I would use jQuery to add an element to the form containing the text of the validation error when it occurs. If the servlet returns an empty string or JSON object or something, I would consider it a validation success.
i'm somewhat new to jinput and java in general and was wondering, what's the easiest way to set up multiple xbox 360 controllers (particularly 4) with jinput? currently, i'm currently going off of theuzo007's tutorial on jinput with controllers, and have a basic working controller setup going on. it would be fantastic if i could set what controller moves certain entities around. (i'm using my friend's homemade library, just so you know.)
screenshot -
http://imgur.com/a/1Ocu5
top one is the main block of code, last one is the header (sorry for putting them in the wrong order, imgur does that sometimes!)
if anyone could help me out, that would be great, thanks!
edit: if there's no possible way to do it, if anyone could try to reccomend a new library to me, that would be cool.
There is a possible way
That tutorial is pretty good. Furthermore, I think you can do the 4 controllers stuff by copy-pasting some code inside the zip theuzo007 provides you and a bit more. By the way, that page that you liked says that there is a better version of that tutorial where you can download an also better version of his code -> theuzo007's JInput tutorial V2
Once you download the code you can see that in JoystickTest.java there is a method called searchForControllers() that you can put (With the corresponding private ArrayList<Controller> foundControllers; as field) in a class called ControllerChecker or some cooler name. Make them all static and you will get something like this:
public class ControllerChecker {
private static ArrayList<Controller> foundControllers = null;
/**
* Just used for checking all available controllers.
*/
private static void searchForControllers() {
Controller[] controllers = ControllerEnvironment.getDefaultEnvironment().getControllers();
for(int i = 0; i < controllers.length; i++){
Controller controller = controllers[i];
if (
controller.getType() == Controller.Type.STICK ||
controller.getType() == Controller.Type.GAMEPAD ||
controller.getType() == Controller.Type.WHEEL ||
controller.getType() == Controller.Type.FINGERSTICK
)
{
// Add new controller to the list of all controllers.
foundControllers.add(controller);
// Add new controller to the list on the window.
window.addControllerName(controller.getName() + " - " + controller.getType().toString() + " type");
}
}
}
/**
* Returns null if there is no controller available. Otherwise, it retrieves the last controller in the list by removing it.
*/
public static Controller getController() {
if(foundControllers == null) {
foundControllers = new ArrayList<Controller>();
searchForControllers();
}
return foundControllers.size() == 0 ? null : foundControllers.remove(foundControllers.size() - 1);
}
}
You would use the static method getController() to make the players have a different controller, checking if the returned controller is null, meaning that there is no available controller. Also you can change my code and check for controllers everytime you ask for one, but you have to check if the controller is already in use.
I hope this helps you in your purpose. This solution just checks for all available controllers and returns then in the last order it found them (maybe using a Stack is more efficient). But probably you will want more functionality like being able to tell the program to select a specific controller by pressing a button, maybe in a screen that says "Please, connect your controller and press any key/button". This can be achieve easily if you understand theuzo007's code (the JoystickTest.java has a lot of useful lines!).
Also you can make some mechanism to detect unpluged controllers and just by plugging in them again the system recognize it. Maybe there is some controller id, I haven't found it yet.
Finally, there is more code here.