JvDataSource has an OnRecordChanged event which, as the name suggests, should be fired whenever current record is changed. But it doesn't fire at all. In fact, even OnUpdateData isn't fired at all. I'm beginning to suspect that something is really wrong with either my JVCL installation, or JvDataSource component. Even a fresh installation didn't solve the mentioned problems. Is anyone out there using JvDataSource in their applications at all? And, if yes, have you ever observed such behavior?
PS: Before you ask, I have tried all combinations of DisableEventsOnLoading, and EventsEnabled.
Thanks to Sertac. It was a misunderstanding on my part. OnRecordChanged is called whenever the record is edited.
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I am loosing my patience with "delay write failed" errors. It silently disconnects the database from the application so nothing gets saved in the database while using it. Is there a way to detect the occurrence itself so I can flash a warning ? Or perhaps monitoring the connection itself for a disconnection ? Everyone seems to miss the balloon tip from the Windows XP so I figured to flash a more visible warning that the application must be restarted. It seems Microsoft has found a way to force people to upgrade....
I suppose this could be done with a timer and constantly check connected users:
cxlabel1.Caption := IntToStr(DataModule2.ABSDatabase1.GetDBFileConnectionsCount);
But I was thinking more of checking/detecting for the occurence itself. Is there something in Delphi that can detect this?
I would like to hear your ideas on this...
Putting this as an answer because the comment length is limited.
I have seen this before. IIRC, the problem you have is that the Delayed Write Error is an OS error, it has nothing to do with your application. Windows has already told you that the write has been committed correctly to disk. You would have to try and hook into the OS errors to see when this is happening.
You need to get the network issues resolved because that's where the problem is. In our situation it was a faulty router that was causing the problem.
It's unfair to expect users to check for the error message and then handle it. They could be out at lunch when it occurs as it's not immediate. They also have no way of know what has been saved and what hasn't. It's only a matter of time before your database is corrupted.
The problem with a timer is that it might tell you everything is fine because it triggers after the network resolves the problems.
A far better approach would be to switch to a Client/Server database. You can do this by setting up your own server that listens for web service or another remote call or switch to a database that supports client/server instead of using a file based database. This will tell you immediately when there is a problem with the save of data.
Here is a simple question.
suppose that I have a very long loop to execute, It would be nice to keep the user informed about the progressing right? I would print for example the number of loops that have been executed so far and how many are remaining.
The problem that I have is those output wouldn't be visualized until the the loop is finished, and thus there will be no point for them to be displayed.
I'm sure that there is some method in dart that can some sort of a handler to the browser to execute tasks and events whenever I want to and keep running the loop.
I'm new to dart, I hope that someone could answer this question.
Thank you.
PS: If you don't know how to, you can give me any ideas of keywords that I can use to look for this particular feature in dart documentation, it will be very helpful.
You can dig into Isolates, which allow background work on supported browsers.
https://api.dartlang.org/docs/channels/stable/latest/dart_isolate.html
Nothing as simple as DoEvents(), but all of the pieces are there.
I think too that Isolates are the best approach but wasn't successful using them on the browser a while ago, but there was a bigger refactoring going on lately in Isolates.
Does anyone know of a current client side Isolates example?
The API doc referenced by #kevmoo contains a link to an Isolates article that doesn't exist anymore (maybe must be rewritten due to the mentioned refactoring).
Another approach would be a method that returns after a chunk of work and gets recalled repeated in a loop until it returns for example true for done (false for not yet).
When you call this method using scheduleMicrotask(doChunk) or new Timer(() => doChunk()) other tasks get some air (import 'dart:async';) each time before the method gets actually called.
I have a problem I cannot solve. Of course here I just expect to have a suggestion that can help me to find a solution.
Basically my application is full of runtime generated TPopupMenuItems (while all the TPopupMenus are hardcoded). In some cases what I do is simply hide/show or enable/disable items, in other cases I create items at runtime.
In some machines only, after leaving the application running for days (2 or more) the popupmenus don't work anymore correctly.
The behaviour is:
all the TPopupmenu items look are the same, and execute the same action.
The action is the one performed by the first TPopupMenuItem of the application (the first generated at runtime when the application starts, this is the only hint I have).
Imagine in correct scenario I have (in a 3-items-TPopupMenu):
Item23
Item24
Item25
after the problem I see:
Item1
Item1
Item1
(where Item1 is the TPopupMenuItem belonging to another TPopupMenu).
Does this tell you something?
Thanks.
Update:
I tried to look at the code of my popupmenus and I found what could be a common cause, and this explains also why FastMM4 didn't find this:
while mnuItem.Count > 0 do
mnuItem.Delete(0);
Delete (I just read in the documentation) doesn't free the item, I should call free instead. Anyway when closing the application the main popupmenus are freed correctly, and FastMM4 doesn't complain. So this is probably the solution, now I don't know why Delete was used, I didn't write that code.
Further update:
I tried to make a sample application, I couldn't reproduce the problem, but for sure I noticed that using this is much more performant (I tried a loop with 10000 recursions):
while mnuItem.Count > 0 do
mnuItem.Items[0].Free;
I will try for this in my app (but I need to let some days pass to really know if I got the problem, ayway for sure this is a major improvement anyway).
I confirm that the problem was linked to Delete instead of Free. Popupmenu wsa refreshed every minute on the machines that had the problem (so it was not OS or HW specific, just config specific). Then according to user settings the menu could have 10 to 100 items, so leaving it idle for days made it possible to hit the handle limit.
By the way it also makes no sense to refresh the popupmenu in that way, so I found also an optimizaion removed a bug.
Did you check for memory leakage and handles that aren't freed?
Experiencing jquery in rails through .js.erb templates; but completely puzzled by a simple problem : for some reason, when a certain controller's action is called, it is recalled like two or three times. and on top of that, the number of recalls to the same action increase as the page is used. so i quickly end up with long loops over the same action...
there's a real logic in this bug, but still, can get hat it is and how to solve it.
ay experiences with tose kind of problems ?
Try unbind(ing) the event before attaching it. that helps with my stuff from time to time.
If you are using the live keyword then stop using it. if you are not, then try using it. i know that sounds like rubbish advice but i have done these steps in the past to fix issues exactly like you describe.
also, if on your success of the jquery call, ensure you are not rebinding events on a set of objects defined by a class. that will also add events to controls.
LEGACY ALERT - This is for Delphi 5 code. (I know it is super old. It is scheduled to be rewritten.... Some day.)
I am using the BDE and the TStoredProc object. When I call Close, this normally clears my dataset. However, I am seeing weird things happen so I thought I would ask this question.
If I have manually added rows to the dataset (i.e. via the Append method) then when I call close are they going to be deleted as well?
Not sure with D5 and BDE, but I would say that you have to do an explicit Post to ensure the added record is actually stored.
if you dont post they should be getting deleted