Myujth

I have implemented a plain vanilla MVVM apps. I have a datagrid bound to an ObservableCollection. When the database is refreshed, the collection is updated, the OnPropertyChanged is correctly fired but there is a lag before the UI is properly refreshed. I can tell that because when I debug, I can see that there is a few second between the moment the OnPropertyChanged is fired and the get accessor of the ObservableCollection is called. The lag does not seems to be correlated to the number of rows (ie 5 or 50 rows, it seems that there is the same lag).

Where can I start to find out where does this lag comes from ?

Code:
It is plain vanille MVVM hence:

private ObservableCollection<MyVar> _MyVars;
/// <summary>
/// List of pnl
/// </summary>
public ObservableCollection<MyVar> MyVars

 get
 
 return _MyVars;
 
 set
 
 _MyVars = value;
 OnPropertyChanged("MyVars");
 

The ObservableCollection MyVars is set by a call to a database. Basically what is happening is a lag between the call to OnPropertyChanged("MyVars"); and the call to return _MyVars;. MyVars is the item source for a datagrid.
Both in release and debug, the datagrid takes a few seconds to refresh and I found out that the lag is coming between the two calls I mentionned above. I can't put more code than that, I was just wondering If somebody had the same situation and which path did he/she took to debug and solve the problem.

Thanks,

Pierre

Why are you re-assinging an ObservableCollection property? Just create it once and add / remove items as required.

private ObservableCollection<MyVar> _myVarsCollection = new ObservableCollection<MyVar>();

public IEnumerable<MyVar> MyVars => _myVarsCollection;

public void AddMyVar(MyVar myVar)

 _myVarsCollection.Add(myVar);


public void AddMyVars(IEnumerable<MyVar> myVars)

 foreach(var myvar in myVars)
 AddMyVar(myvar); 


public void RemoveMyVar(MyVar myVar)

 _myVarsCollection.Remove(myVar);

Even though _myVarsCollection is not public, any control bound to MyVars will detect that it implements INotifyCollectionChanged and will react accordingly when items are added / removed.