I am working on an xtext Project where I have to customize the Scope Provider. I need to add up some possible candidates for the scope. The first part (getServiceInputs()) works fine but for the second one (addAll(sub.GetSubRecipeParameters()) not. Debugging showed that they get removed from its original source (sub) and can therefore not be retrieved again. When simply commenting out the addAll line the SubRecipeParameters remain in sub. Really dont know how to solve that, tried already some work arounds. Anyone with an Idea?
public class AutomationServiceDslScopeProvider extends AbstractAutomationServiceDslScopeProvider {
#Override
public IScope getScope(EObject context, EReference reference) {
if (context instanceof ServiceInvocationParameter
&& reference == AutomationServiceDslPackage.Literals.LITERAL) {
ServiceInvocation serviceCall = (ServiceInvocation) invocationParameter.eContainer();
ServiceDefinition calledService = serviceCall.getService();
List<ServiceParameterDefinition> candidates= calledService.getServiceInputs();
final EObject rootContainer = EcoreUtil.getRootContainer(context);
List<SubRecipeDefinition> subs = EcoreUtil2.getAllContentsOfType(rootContainer, SubRecipeDefinition.class);
for(SubRecipeDefinition sub:subs) {
for(RecipeStep step:sub.getRecipeSteps()) {
if(step.getName()==serviceCall.getName()) {
candidates.addAll(sub.getSubRecipeParameters());
}
}
}
return Scopes.scopeFor(candidates);
Thanks for any help!!
This is normal EMF behaviour if you move elements from one EList to another one. The solution is to create a new list e.g. new ArrayList<>() and also add the inputs there
List<ServiceParameterDefinition> candidates = new ArrayList<>();
candidates.addAll(calledService.getServiceInputs());
I'm using a Grid in Vaadin 14. The grid is in multi-selection mode.
The selection handler takes a couple of seconds to complete and I'm calling setItems(...) at the end to update the items in the grid.
When the user selects another row while the previous selection handler is still running, I get an "Unknown key" error similar to the one described in https://github.com/vaadin/vaadin-grid-flow/issues/322, even though the new set of items still contains the selected item (another object instance but same according to equals()). This seems to be because the keys in the KeyMapper have already been changed due to setItems(), so the key coming from the client is not present anymore.
Is there a way to work around this, for example by disabling selection while the previous request is in progress?
UPDATE
To work around this Vaadin bug, I'm also calling setPageSize() with the exact number of items as argument. But it seems the same problem occurs even if I don't call setPageSize(), so it's probably due to setItems().
Do not change the grids items inside a SelectionListener.
You can still do all the things you wanted, but setting the items anew is not actually needed. In fact it will only create problems as you are experiencing now.
While working at this answer, I realized you will need to do your own Checkbox Column in order to be able to do actions for the one item that was just "selected", instead of removing all then add all selected ones (because much better performance). Here is how that could look.
// in my code samples, a `Foo` item can have many `Bar` items. The grid is of type Bar.
Grid.Column customSelectionColumn = grid.addComponentColumn(item -> {
Checkbox isSelected = new Checkbox();
isSelected.setValue(someParentFoo.getBars().contains(item));
isSelected.addValueChangeListener(event -> {
boolean newSelectedValue = event.getValue();
if(newSelectedValue){
someParentFoo.getBars().add(item)
} else {
someParentFoo.getBars().remove(item);
}
fooRepository.save(someParentFoo);
});
});
// make a Checkbox that selects all in the header
Checkbox toggleSelectAll = new Checkbox();
toggleSelectAll.addValueChangeListener(event -> {
if(event.getValue()){
someParentFoo.getBars().addAll(allGridItems);
} else {
someParentFoo.getBars().removeAll(allGridItems);
}
fooRepository.save(someParentFoo);
grid.getDataProvider().refreshAll(); // updates custom checkbox value of each item
});
gridHeaderRow.getCell(customSelectionColumn).setComponent(toggleSelectAll);
I solved this problem. Vaadin use data as key in HashMap. You need calc hashCode use immutable data fields. For example
public class TestData {
private int id;
private String name;
public TestData(int id) {
this.id = id;
}
#Override
public int hashCode() {
return Objects.hash(id);
}
public int getId() {
return id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
I've read several related posts and even posted and answer here but it seems like I was not able to solve the problem.
I have 3 Activities:
Act1 (main)
Act2
Act3
When going back and forth Act1->Act2 and Act2->Act1 I get no issues
When going Act2->Act3 I get no issues
When going Act3->Act2 I get occasional crashes with the following error: java.lang.IllegalStateException: trying to requery an already closed cursor android.database.sqlite.SQLiteCursor#.... This is a ListView cursor.
What I tried:
1. Adding stopManagingCursor(currentCursor);to the onPause() of Act2 so I stop managing the cursor when leaving Act2 to Act3
protected void onPause()
{
Log.i(getClass().getName() + ".onPause", "Hi!");
super.onPause();
saveState();
//Make sure you get rid of the cursor when leaving to another Activity
//Prevents: ...Unable to resume activity... trying to requery an already closed cursor
Cursor currentCursor = ((SimpleCursorAdapter)getListAdapter()).getCursor();
stopManagingCursor(currentCursor);
}
When returning back from Act3 to Act2 I do the following:
private void populateCompetitorsListView()
{
ListAdapter currentListAdapter = getListAdapter();
Cursor currentCursor = null;
Cursor tournamentStocksCursor = null;
if(currentListAdapter != null)
{
currentCursor = ((SimpleCursorAdapter)currentListAdapter).getCursor();
if(currentCursor != null)
{
//might be redundant, not sure
stopManagingCursor(currentCursor);
// Get all of the stocks from the database and create the item list
tournamentStocksCursor = mDbHelper.retrieveTrounamentStocks(mTournamentRowId);
((SimpleCursorAdapter)currentListAdapter).changeCursor(tournamentStocksCursor);
}
else
{
tournamentStocksCursor = mDbHelper.retrieveTrounamentStocks(mTournamentRowId);
}
}
else
{
tournamentStocksCursor = mDbHelper.retrieveTrounamentStocks(mTournamentRowId);
}
startManagingCursor(tournamentStocksCursor);
//Create an array to specify the fields we want to display in the list (only name)
String[] from = new String[] {StournamentConstants.TblStocks.COLUMN_NAME, StournamentConstants.TblTournamentsStocks.COLUMN_SCORE};
// and an array of the fields we want to bind those fields to (in this case just name)
int[] to = new int[]{R.id.competitor_name, R.id.competitor_score};
// Now create an array adapter and set it to display using our row
SimpleCursorAdapter tournamentStocks = new SimpleCursorAdapter(this, R.layout.competitor_row, tournamentStocksCursor, from, to);
//tournamentStocks.convertToString(tournamentStocksCursor);
setListAdapter(tournamentStocks);
}
So I make sure I invalidate the cursor and use a different one. I found out that when I go Act3->Act2 the system will sometimes use the same cursor for the List View and sometimes it will have a different one.
This is hard to debug and I was never able to catch a crashing system while debugging. I suspect this has to do with the time it takes to debug (long) and the time it takes to run the app (much shorter, no pause due to breakpoints).
In Act2 I use the following Intent and expect no result:
protected void onListItemClick(ListView l, View v, int position, long id)
{
super.onListItemClick(l, v, position, id);
Intent intent = new Intent(this, ActivityCompetitorDetails.class);
intent.putExtra(StournamentConstants.App.competitorId, id);
intent.putExtra(StournamentConstants.App.tournamentId, mTournamentRowId);
startActivity(intent);
}
Moving Act1->Act2 Act2->Act1 never gives me trouble. There I use startActivityForResult(intent, ACTIVITY_EDIT); and I am not sure - could this be the source of my trouble?
I would be grateful if anyone could shed some light on this subject. I am interested in learning some more about this subject.
Thanks,D.
I call this a 2 dimensional problem: two things were responsible for this crash:
1. I used startManagingCursor(mItemCursor); where I shouldn't have.
2. I forgot to initCursorAdapter() (for autocomplete) on onResume()
//#SuppressWarnings("deprecation")
private void initCursorAdapter()
{
mItemCursor = mDbHelper.getCompetitorsCursor("");
startManagingCursor(mItemCursor); //<= this is bad!
mCursorAdapter = new CompetitorAdapter(getApplicationContext(), mItemCursor);
initItemFilter();
}
Now it seems to work fine. I hope so...
Put this it may work for you:
#Override
protected void onRestart() {
// TODO Auto-generated method stub
super.onRestart();
orderCursor.requery();
}
This also works
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB) {
startManagingCursor(Cursor);
}
I've been working on this problem for quite a while but have not been able to solve it.
I have a listgrid with a field type icon. I would like to change the cursor to "hand" over the icon.
I've been searching the web and saw that a couple of solutions existed.
One of them is using addCellOverHandler for the list grid. But I don't understand how you can change the cursor for the specified field of the listgrid.
this.addCellOverHandler(new CellOverHandler() {
#Override
public void onCellOver(CellOverEvent event) {
// not able to get the field and setCursor()
}
});
My field in the listgrid is defined as:
ListGridField iconField = new ListGridField("icon");
iconField.setAlign(Alignment.CENTER);
iconField.setType(ListGridFieldType.ICON);
iconField.setIcon("icons/icon.gif");
Like someone pointed out on the forum, a setCursor() method exist for the listgrid, but not for the field only...
If anybody has a clue...
Thanks
After some more (a lot more...) googling, I found this:
http://forums.smartclient.com/showthread.php?t=15748
The thing is to Override the getCellStyle method in the listgrid.
Here is the code I use:
#Override
protected String getCellStyle(ListGridRecord record, int rowNum, int colNum) {
if (colNum==6){
return "EC_pointer";
}
return super.getCellStyle(record, rowNum, colNum);
}
and in my CSS file:
.EC_pointer {
cursor: pointer;
}
The major fallout is that you have to know in advance the column number of the field.
Further to my comment and adding information from here I tested the following code which works with SmartGwt2.4 under Firefox 5.0.
demandesGrid.setCanHover(true);
demandesGrid.setShowHover(false);
demandesGrid.addCellHoverHandler(new CellHoverHandler() {
#Override
public void onCellHover(CellHoverEvent event) {
if (event.getColNum() == demandesGrid.getFieldNum("icon")) {
// SC.say(demandesGrid.getChildren()[3].toString());
demandesGrid.getChildren()[3].setCursor(Cursor.POINTER);
} else {
demandesGrid.getChildren()[3].setCursor(Cursor.DEFAULT);
}
}
});
I don't know if the index of the ListGridBody is constant; I found it with the SC.say line.
How about
grid.addCellOverHandler(new CellOverHandler() {
#Override
public void onCellOver(CellOverEvent event) {
//cellOver event to get field and refresh the cell
//grid.refreshCell(i, j);
}
});
The best approach is fully demonstrated here (take a look at how "comments/stats" field is being initialized).
In short, u have to extend ListGrid and override createRecordComponent method. In this method you can make any custom component you like and it will be show in grid cell.
Also ListGrid should be initialized with:
listGrid.setShowRecordComponents(true);
listGrid.setShowRecordComponentsByCell(true);
I want to prevent users submitting forms multiple times in .NET MVC. I've tried several methods using Javascript but have had difficulties getting it to work in all browsers. So, how can I prevent this in my controller? It there some way that multiple submissions can be detected?
Updated answer for ASP.NET Core MVC (.NET Core & .NET 5.0)
Update note: Remember ASP.NET Core is still called "Core" in .NET 5.0.
I'm going to stick to the least-impact use case like before, where you're only adorning those controller actions that you specifically want to prevent duplicate requests on. If you want to have this filter run on every request, or want to use async, there are other options. See this article for more details.
The new form tag helper now automatically includes the AntiForgeryToken so you no longer need to manually add that to your view.
Create a new ActionFilterAttribute like this example. You can do many additional things with this, for example including a time delay check to make sure that even if the user presents two different tokens, they aren't submitting multiple times per minute.
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
public class PreventDuplicateRequestAttribute : ActionFilterAttribute {
public override void OnActionExecuting(ActionExecutingContext context) {
if (context.HttpContext.Request.HasFormContentType && context.HttpContext.Request.Form.ContainsKey("__RequestVerificationToken")) {
var currentToken = context.HttpContext.Request.Form["__RequestVerificationToken"].ToString();
var lastToken = context.HttpContext.Session.GetString("LastProcessedToken");
if (lastToken == currentToken) {
context.ModelState.AddModelError(string.Empty, "Looks like you accidentally submitted the same form twice.");
}
else {
context.HttpContext.Session.SetString("LastProcessedToken", currentToken);
}
}
}
}
By request, I also wrote an asynchronous version which can be found here.
Here's a contrived usage example of the custom PreventDuplicateRequest attribute.
[HttpPost]
[ValidateAntiForgeryToken]
[PreventDuplicateRequest]
public IActionResult Create(InputModel input) {
if (ModelState.IsValid) {
// ... do something with input
return RedirectToAction(nameof(SomeAction));
}
// ... repopulate bad input model data into a fresh viewmodel
return View(viewModel);
}
A note on testing: simply hitting back in a browser does not use the same AntiForgeryToken. On faster computers where you can't physically double click the button twice, you'll need to use a tool like Fiddler to replay your request with the same token multiple times.
A note on setup: Core MVC does not have sessions enabled by default. You'll need to add the Microsoft.AspNet.Session package to your project, and configure your Startup.cs properly. Please read this article for more details.
Short version of Session setup is:
In Startup.ConfigureServices() you need to add:
services.AddDistributedMemoryCache();
services.AddSession();
In Startup.Configure() you need to add (before app.UseMvc() !!):
app.UseSession();
Original answer for ASP.NET MVC (.NET Framework 4.x)
First, make sure you're using the AntiForgeryToken on your form.
Then you can make a custom ActionFilter:
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
public class PreventDuplicateRequestAttribute : ActionFilterAttribute {
public override void OnActionExecuting(ActionExecutingContext filterContext) {
if (HttpContext.Current.Request["__RequestVerificationToken"] == null)
return;
var currentToken = HttpContext.Current.Request["__RequestVerificationToken"].ToString();
if (HttpContext.Current.Session["LastProcessedToken"] == null) {
HttpContext.Current.Session["LastProcessedToken"] = currentToken;
return;
}
lock (HttpContext.Current.Session["LastProcessedToken"]) {
var lastToken = HttpContext.Current.Session["LastProcessedToken"].ToString();
if (lastToken == currentToken) {
filterContext.Controller.ViewData.ModelState.AddModelError("", "Looks like you accidentally tried to double post.");
return;
}
HttpContext.Current.Session["LastProcessedToken"] = currentToken;
}
}
}
And on your controller action you just...
[HttpPost]
[ValidateAntiForgeryToken]
[PreventDuplicateRequest]
public ActionResult CreatePost(InputModel input) {
...
}
You'll notice this doesn't prevent the request altogether. Instead it returns an error in the modelstate, so when your action checks if ModelState.IsValid then it will see that it is not, and will return with your normal error handling.
I've tried several methods using Javascript but have had difficulties getting it to work in all browsers
Have you tried using jquery?
$('#myform').submit(function() {
$(this).find(':submit').attr('disabled', 'disabled');
});
This should take care of the browser differences.
Just to complete the answer of #Darin, if you want to handle the client validation (if the form has required fields), you can check if there's input validation error before disabling the submit button :
$('#myform').submit(function () {
if ($(this).find('.input-validation-error').length == 0) {
$(this).find(':submit').attr('disabled', 'disabled');
}
});
What if we use $(this).valid()?
$('form').submit(function () {
if ($(this).valid()) {
$(this).find(':submit').attr('disabled', 'disabled');
}
});
Strategy
The truth is that you need several lines of attack for this problem:
The Post/Redirect/Get (PRG) pattern is not enough by itself. Still, it should always be used to provide the user with good experiences when using back, refresh, etc.
Using JavaScript to prevent the user from clicking the submit button multiple times is a must because it provides a much less jarring user experience compared to server-side solutions.
Blocking duplicate posts solely on the client side doesn't protect against bad actors and does not help with transient connection problems. (What if your first request made it to the server but the response did not make it back to the client, causing your browser to automatically resend the request?)
I'm not going to cover PRG, but here are my answers for the other two topics. They build upon the other answers here. FYI I'm using .NET Core 3.1.
Client-Side
Assuming you are using jQuery validation, I believe this is the cleanest/most efficient way to prevent your form submit button from being double-clicked. Note that submitHandler is only called after validation has passed, so there is no need to re-validate.
$submitButton = $('#submitButton');
$('#mainForm').data('validator').settings.submitHandler = function (form) {
form.submit();
$submitButton.prop('disabled', true);
};
An alternative to disabling the submit button is to show an overlay in front of the form during submission to 1) block any further interaction with the form and 2) communicate that the page is "doing something." See this article for more detail.
Server-Side
I started off with Jim Yarbro's great answer above, but then I noticed Mark Butler's answer pointing out how Jim's method fails if someone submits forms via multiple browser tabs (because each tab has a different token and posts from different tabs can be interlaced). I confirmed that such a problem really does exist and then decided to upgrade from tracking just the last token to tracking the last x tokens.
To facilitate that, I made a couple of helper classes: one for storing the last x tokens and one for making it easy to store/retrieve objects to/from session storage. The main code now checks that the current token is not found in the token history. Other than that, the code is pretty much the same. I just made some little tweaks to suit my tastes. I included both the regular and asynchronous versions. The full code is below, but these are the critical lines:
var history = session.Get<RotatingHistory<string>>(HistoryKey) ?? new RotatingHistory<string>(HistoryCapacity);
if (history.Contains(token))
{
context.ModelState.AddModelError("", DuplicateSubmissionErrorMessage);
}
else
{
history.Add(token);
}
Sadly, the fatal flaw of this approach is that the feedback from the first post (before any duplicates) gets lost. A better (but much more complex) solution would be to store the result of each unique request by GUID, and then handle duplicate requests by not only skipping doing the work again but also returning the same result from the first request, giving the user a seamless experience. This thorough article detailing Air BnB's methods of avoiding duplicate payments will give you an idea of the concepts.
PreventDuplicateFormSubmissionAttribute.cs
using System;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc.Filters;
// This class provides an attribute for controller actions that flags duplicate form submissions
// by adding a model error if the request's verification token has already been seen on a prior
// form submission.
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
public class PreventDuplicateFormSubmissionAttribute: ActionFilterAttribute
{
const string TokenKey = "__RequestVerificationToken";
const string HistoryKey = "RequestVerificationTokenHistory";
const int HistoryCapacity = 5;
const string DuplicateSubmissionErrorMessage =
"Your request was received more than once (either due to a temporary problem with the network or a " +
"double button press). Any submissions after the first one have been rejected, but the status of the " +
"first one is unclear. It may or may not have succeeded. Please check elsewhere to verify that your " +
"request had the intended effect. You may need to resubmit it.";
public override void OnActionExecuting(ActionExecutingContext context)
{
HttpRequest request = context.HttpContext.Request;
if (request.HasFormContentType && request.Form.ContainsKey(TokenKey))
{
string token = request.Form[TokenKey].ToString();
ISession session = context.HttpContext.Session;
var history = session.Get<RotatingHistory<string>>(HistoryKey) ?? new RotatingHistory<string>(HistoryCapacity);
if (history.Contains(token))
{
context.ModelState.AddModelError("", DuplicateSubmissionErrorMessage);
}
else
{
history.Add(token);
session.Put(HistoryKey, history);
}
}
}
public override async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
{
HttpRequest request = context.HttpContext.Request;
if (request.HasFormContentType && request.Form.ContainsKey(TokenKey))
{
string token = request.Form[TokenKey].ToString();
ISession session = context.HttpContext.Session;
await session.LoadAsync();
var history = session.Get<RotatingHistory<string>>(HistoryKey) ?? new RotatingHistory<string>(HistoryCapacity);
if (history.Contains(token))
{
context.ModelState.AddModelError("", DuplicateSubmissionErrorMessage);
}
else
{
history.Add(token);
session.Put(HistoryKey, history);
await session.CommitAsync();
}
await next();
}
}
}
RotatingHistory.cs
using System.Linq;
// This class stores the last x items in an array. Adding a new item overwrites the oldest item
// if there is no more empty space. For the purpose of being JSON-serializable, its data is
// stored via public properties and it has a parameterless constructor.
public class RotatingHistory<T>
{
public T[] Items { get; set; }
public int Index { get; set; }
public RotatingHistory() {}
public RotatingHistory(int capacity)
{
Items = new T[capacity];
}
public void Add(T item)
{
Items[Index] = item;
Index = ++Index % Items.Length;
}
public bool Contains(T item)
{
return Items.Contains(item);
}
}
SessonExtensions.cs
using System.Text.Json;
using Microsoft.AspNetCore.Http;
// This class is for storing (serializable) objects in session storage and retrieving them from it.
public static class SessonExtensions
{
public static void Put<T>(this ISession session, string key, T value) where T : class
{
session.SetString(key, JsonSerializer.Serialize(value));
}
public static T Get<T>(this ISession session, string key) where T : class
{
string s = session.GetString(key);
return s == null ? null : JsonSerializer.Deserialize<T>(s);
}
}
You could include a hidden (random or counter) value in the form post, a controller could track these values in an 'open' list or something similar; every time your controller hands out a form it embeds a value, which it tracks allowing one post use of it.
In its self, no, however depending on what the controller is actually doing, you should be able to work out a way.
Is a record being created in the database that you can check for to see if they've already submitted the form?
Just add this code at the end of your page. I am using "jquery-3.3.1.min.js" and "bootstrap 4.3.1"
<script type="text/javascript">
$('form').submit(function () {
if ($(this).valid()) {
$(this).find(':submit').attr('disabled', 'disabled');
}
});
</script>
Use the Post/Redirect/Get design pattern.
PS:
It looks to me that the answer by Jim Yarbro could have a fundamental flaw in that the __RequestVerificationToken stored in the HttpContext.Current.Session["LastProcessedToken"] will be replaced when a second form is submitted (from say another browser window). At this point, it is possible to re-submit the first form without it being recognized as a duplicate submission. For the proposed model to work, wouldn’t a history of __RequestVerificationToken be required? This doesn't seem feasible.
Dont reinvent the wheel :)
Use the Post/Redirect/Get design pattern.
Here you can find a question and an answer giving some suggestions on how to implement it in ASP.NET MVC.
You can also pass some sort of token in a hidden field and validate this in the controller.
Or you work with redirects after submitting values. But this get's difficult if you take heavily advantage of ajax.
This works on every browser
document.onkeydown = function () {
switch (event.keyCode) {
case 116: //F5 button
event.returnValue = false;
event.keyCode = 0;
return false;
case 82: //R button
if (event.ctrlKey) {
event.returnValue = false;
event.keyCode = 0;
return false;
}
}
}
You can do this by creating some sort of static entry flag that is user specific, or specific to whatever way you want to protect the resource. I use a ConcurrentDictionary to track entrance. The key is basically the name of the resource I'm protecting combined with the User ID. The trick is figuring out how to block the request when you know it's currently processing.
public async Task<ActionResult> SlowAction()
{
if(!CanEnterResource(nameof(SlowAction)) return new HttpStatusCodeResult(204);
try
{
// Do slow process
return new SlowProcessActionResult();
}
finally
{
ExitedResource(nameof(SlowAction));
}
}
Returning a 204 is a response to the double-click request that will do nothing on the browser side. When the slow process is done, the browser will receive the correct response for the original request and act accordingly.
Use this simple jquery input field and will work awesomely even if you have multiple submit buttons in a single form.
$('input[type=submit]').click(function () {
var clickedBtn = $(this)
setTimeout(function () {
clickedBtn.attr('disabled', 'disabled');
}, 1);
});