How to use _Asyn methods correctly ?
With my limited experience with C#, I don't know why. How to improve it? Thanks in advance.
//use :
this.SyncDataDataGridView.DataSource = await patentLaunch.LoadAccessDbListAsync();
//Method-01 winfroms UI OK (use ToList() )
public async Task<List<SyncNotice>> LoadAccessDbListAsync01()
{
return await Task.Run(() =>
{
using (var context = new SyncDbContextContext())
{
return context.SyncNotices.OrderByDescending(m => m.Id).Take(1000).ToList();
}
});
}
//Method-02 winfroms UI freeze ! ( use ToListAsync() EntityFrameworkCore )
public Task<List<SyncNotice>> LoadAccessDbListAsync02()
{
using (var context = new SyncDbContextContext())
{
return context.SyncNotices.OrderByDescending(m => m.Id).Take(1000).ToListAsync();
}
}
my full code is:
private async void Form_Load(object sender, EventArgs e){
//init binding
await context.SyncNotices.LoadAsync();
this.SyncDataDataGridView.DataSource = context.SyncNotices.Local.ToBindingList();
}
//init event
patentLaunch.OnFolderAddAccessOk += () => {
Invoke(new Action(async () =>
{
this.SyncDataDataGridView.DataSource = await patentLaunch.LoadAccessDbListAsync02();
}));
};
};
}
//call in fileSystemWatcher1_Created(object sender, System.IO.FileSystemEventArgs e)
//in patentLaunch.cs
public void AddSigleFloderToAccessDb(string folder, string syncStatus)
{
var now = DateTime.Now;
var entity = new SyncNotice
{
FolderName = folder,
CreateTime = now,
SyncStatus = syncStatus
};
using (var context = new SyncDbContextContext())
{
context.SyncNotices.Add(entity);
context.SaveChanges();
}
UpdateLastExecTime(now);
// send event
OnFolderAddAccessOk();
}
//in patentLaunch.cs
public event Action OnFolderAddAccessOk;
Thanks for JonasH . Thank you for your reply. ,finally I used mehtod01
Some databases do not support truly async queries. In that case queries may be synchronous even if there is a *Async-method.
I have not found any concrete documentation about access supporting or not supporting asynchronous queries. But based on its age, and the fact that your call is actually blocking, I would guess the chances are low.
So as far as I know you just have to use LoadAccessDbListAsync01 to avoid blocking.
