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this is a keyword in C# which always represents the current instance of the current class - as such it s only ever available in non-static methods, because static code does not and cannot refer to an instance at all.
It's like a car: "my car" is an instance, "your car" is a different instance. But "this car" could refer to either, and the question "what colour is this car?" will return a different value depending on which instance we are talking about. If we are driving in my car, then the answer would be "black" because "my car" is a black Mercedes. If your BMW is being driven then the answer might be "green".r
r and m are parameters which come from the invocation of the lambda: MVVM - The MVVM Light Messenger In-Depth | Microsoft Docs[^] is a good place to start.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
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Hi
I want to apply Client side and Server side validations for Calendar control (for cybersecurity). Can I apply ajax and if so how can I apply both Client side and Server side validations for the control.
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You verify the transaction, not (just) some "control" you think may be the client. By doing too much on the front end (in terms of restricting), you start revealing what will work.
Note how they always say "Your PW or ID is wrong" (Or, guess which).
"Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I
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It seems other users have same problem than me, I can try to re-forumlate my question with other words hoping someone can help me:
I have been Googling and Binging all morning trying to find this answer.
I have a DataGridView that is bound to my SQL database using string builders. I have an update button on my form a user clicks to commit their new changes to the database. However, sometimes, I forget to press "Enter" to activate the event that tells the datagridview there are new changes on the data table. Is there a way to not have to press enter to identify changes?
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That doesent works...
following my "savebutton" what I shoud add to this code in order to aplly changes on DataGridView despite enter is not clicked?
private void salvaClientiBtn_Click(object sender, EventArgs e)
{
tabellaClientiTableAdapter.Update(dataSet.TabellaClienti);
}
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I have the following code for getting data and paginating them inside the DataGrid:
private void dataPager_OnDemandLoading(object sender, Syncfusion.UI.Xaml.Controls.DataPager.OnDemandLoadingEventArgs args)
{
List<Equipment> data;
using (var _sqliteContext = new SQLiteContext())
{
data = _sqliteContext.Equipments.Include(x => x.CostCenter).Skip(args.StartIndex).Take(args.PageSize).ToList();
}
dataPager.LoadDynamicItems(args.StartIndex, data);
(dataPager.PagedSource as PagedCollectionView).ResetCache();
}
Now, I want to use background worker to do calculation in an another thread. I make the following changes:
private void dataPager_OnDemandLoading(object sender, Syncfusion.UI.Xaml.Controls.DataPager.OnDemandLoadingEventArgs args)
{
BackgroundWorker worker = new BackgroundWorker();
worker.WorkerReportsProgress = false;
worker.DoWork += worker_DoWork;
worker.RunWorkerAsync();
}
void worker_DoWork(object sender, DoWorkEventArgs e)
{
List<Equipment> data;
using (var _sqliteContext = new SQLiteContext())
{
data = _sqliteContext.Equipments.Include(x => x.CostCenter).Skip(args.StartIndex).Take(args.PageSize).ToList();
}
dataPager.LoadDynamicItems(args.StartIndex, data);
(dataPager.PagedSource as PagedCollectionView).ResetCache();
}
But, worker_DoWork does not have any overload. I cannot pass args to worker_DoWork
How can I solve it?
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The DoWorkEventArgs class includes an Argument Property[^]
You can set that to an instance of any class (or struct) to pass whatever you need in.
It also contains a Result[^] property for passing completed data back to the caller via the RunWorkerCompleted Event[^]
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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Is it possible to pass more than one instance of any class? Do I need to use List<t> in this case?
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You can use any object - so an int , a MyClass , a collection of IEnumerable objects, an array ... literally anything you need to.
Just be aware that you are multithreaded so you need to ensure thread safety if the argument data is going to be even looked at by two different threads, and that Control derived classes can only be accessed from the thread that created them (the UI thread).
But you almost certainly knew that ... I added it for those other readers who are just getting started with threading.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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I used the following code for getting data from SQLite:
private void dataPager_OnDemandLoading(object sender, Syncfusion.UI.Xaml.Controls.DataPager.OnDemandLoadingEventArgs args)
{
List<int> list = new List<int>()
{
int.Parse(args.StartIndex.ToString()),
int.Parse(args.PageSize.ToString())
};
BackgroundWorker worker = new BackgroundWorker();
worker.WorkerReportsProgress = false;
worker.DoWork += worker_DoWork;
worker.RunWorkerAsync(list);
}
void worker_DoWork(object sender, DoWorkEventArgs e)
{
List<int> value = (List<int>)e.Argument;
List<Equipment> data;
using (var _sqliteContext = new SQLiteContext())
{
data = _sqliteContext.Equipments.Include(x => x.CostCenter).Skip(value[0]).Take(value[1]).ToList();
}
this.Dispatcher.Invoke(() =>
{
dataPager.LoadDynamicItems(value[0], data);
(dataPager.PagedSource as PagedCollectionView).ResetCache();
});
}
There is no runtime error but the table in the UI is empty.
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Start with the debugger and see what data contains before you start the Invoke.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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I debugged. Before Dispatcher.Invoke, the data is full of 50 records. But something happens in Dispatcher.Invoke and prevent data to be shown in the UI.
modified 16-Jul-22 2:16am.
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Could it be that in worker_DoWork your variable data is going out of scope when the function ends?
The difficult we do right away...
...the impossible takes slightly longer.
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Your BackgroundWorker is going to go out of scope; I haven't used that pattern so if it gets "busy", it will be hard to tell, if at all.
"Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I
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Assuming you have to call the LoadDynamicItems from within the event handler, moving the data-loading code to a background thread really won't accomplish anything. You'll still need to block in the event handler until the background thread has finished, so you'll be using two threads to do what you're currently doing with one.
You'll also potentially run into issues if you're working in a framework with a concept of a "UI thread"; the control will most likely expect the LoadDynamicItems method to be called from the UI thread, not a background thread, so you'll end up getting an exception.
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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I'm using Syncfusion in my WPF MVVM project. I want to add pagination to my datagrid. The following code can do this:
private void dataPager_OnDemandLoading(object sender, Syncfusion.UI.Xaml.Controls.DataPager.OnDemandLoadingEventArgs args)
{
using (var _sqliteContext = new SQLiteContext())
{
dataPager.LoadDynamicItems(args.StartIndex, _sqliteContext.Equipments.Include(x => x.CostCenter).Skip(args.StartIndex).Take(args.PageSize));
(dataPager.PagedSource as PagedCollectionView).ResetCache();
}
}
The problem is that when I run the code, the application falls into the break mode and says:
Quote: System.ObjectDisposedException: 'Cannot access a disposed context instance. A common cause of this error is disposing of a context instance that was resolved from dependency injection and then later trying to use the same context instance elsewhere in your application. This may occur if you are calling 'Dispose' on the context instance, or wrapping it in a using statement. If you are using dependency injection, you should let the dependency injection container take care of disposing context instances.
Object name: 'SQLiteContext'.'
How can I fix it?
modified 15-Jul-22 2:28am.
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Code4Ever wrote: This may occur if you are calling 'Dispose' on the context instance, or wrapping it in a using statement. Try reworking without the using statement.
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Thanks. Solved using the following code rework:
private void dataPager_OnDemandLoading(object sender, Syncfusion.UI.Xaml.Controls.DataPager.OnDemandLoadingEventArgs args)
{
List<Equipment> data;
using (var _sqliteContext = new SQLiteContext())
{
data = _sqliteContext.Equipments.Include(x => x.CostCenter).Skip(args.StartIndex).Take(args.PageSize).ToList();
}
dataPager.LoadDynamicItems(args.StartIndex, data);
(dataPager.PagedSource as PagedCollectionView).ResetCache();
}
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I had installed freespride in my asp net core project.
in the view of the controller i have this:
Spire.Doc.Document document = new Spire.Doc.Document();
but i got this error
TypeLoadException: Could not load type 'spride' from assembly 'Spire.Pdf, Version=8.2.2.0
The component it is installed, why the error?
Thanks
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There are so many reasons that this could occur. It might rely on a version of an assembly that you have the wrong version of. You might be missing a dependency somewhere. Plus numerous other reasons. If the full stack of the error doesn't tell you (and we certainly can't from a one-line trace), use depends.exe[^] to see if you can identify missing or incorrect assemblies.
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What is "spride" and where are you trying to load it?
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Hello,
I have a project in vs2019, actually i have the following error and i can not find the error neither in google nor in microsoft, it is says is in line 1, but i can not go to the find.
Any help?
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JSDoc indicates that this is a JavaScript/TypeScript issue and has nothing to do with C#.
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