Update bound ListBox
in [CSharp]
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From: Peter Duniho on 27 Jan 2010 13:00 mick wrote: > [...] > > lbxTabProgList.Refresh(); //*** Tried > this - doesnt work *** > > lbxTabProgList.DataSource = null; // nulling then > resetting the datasource does > > lbxTabProgList.DataSource = progList; // work however > > } > >> Dont think resetting the datasource is the right way so does anyone >> know why the listbox >> update to what it`s bound to? > >> Sorted it. Update() was the one I wanted. > > It worked the first time but doesnt work now, so back to the problem. > Anyone? The Refresh() and Update() methods in Control aren't related to data binding. They simply deal with redrawing the visual on-screen after some underlying data in the control changes. Normally you don't need those methods at all, since changes typically cause a redraw to happen automatically. And even when you might use them, they won't cause underlying data to be updated; they simply cause the control to be redrawn. I think what you want is the BindingList<T>.ResetItem() method. That will alert other objects that are bound to the BindingList<T> object that an individual item within the list has changed. Note that the method takes as its argument an index, not a specific object, while in your code you have a specific object but not an index. Fortunately, this isn't really a problem because the code you've posted actually isn't really the best way to deal with finding the right object in the list and modifying it. Try this instead: private void btnChange_Click(object sender, EventArgs e) { int iitem = lbxTabProgList.SelectedIndex; ProgItem item = progList[iitem]; item.Name = tbTabProgListName.Text; item.Path = tbTabProgListLocation.Text; progList.ResetItem(iitem); } Pete
From: mick on 28 Jan 2010 08:12
"Peter Duniho" <no.peted.spam(a)no.nwlink.spam.com> wrote in message news:%23Cdcaq3nKHA.1544(a)TK2MSFTNGP06.phx.gbl... > mick wrote: >> [...] >> > lbxTabProgList.Refresh(); //*** Tried >> this - doesnt work *** >> > lbxTabProgList.DataSource = null; // nulling then >> resetting the datasource does >> > lbxTabProgList.DataSource = progList; // work however >> > } >> >>> Dont think resetting the datasource is the right way so does anyone know >>> why the listbox >>> update to what it`s bound to? >> >>> Sorted it. Update() was the one I wanted. >> >> It worked the first time but doesnt work now, so back to the problem. >> Anyone? > > The Refresh() and Update() methods in Control aren't related to data > binding. They simply deal with redrawing the visual on-screen after some > underlying data in the control changes. Normally you don't need those > methods at all, since changes typically cause a redraw to happen > automatically. And even when you might use them, they won't cause > underlying data to be updated; they simply cause the control to be > redrawn. > > I think what you want is the BindingList<T>.ResetItem() method. That will > alert other objects that are bound to the BindingList<T> object that an > individual item within the list has changed. > > Note that the method takes as its argument an index, not a specific > object, while in your code you have a specific object but not an index. > Fortunately, this isn't really a problem because the code you've posted > actually isn't really the best way to deal with finding the right object > in the list and modifying it. > > Try this instead: > > private void btnChange_Click(object sender, EventArgs e) > { > int iitem = lbxTabProgList.SelectedIndex; > ProgItem item = progList[iitem]; > > item.Name = tbTabProgListName.Text; > item.Path = tbTabProgListLocation.Text; > > progList.ResetItem(iitem); > } Yep, thats the one. Thanks again. mick |