I'm using EF 6.0 with WPF. I initilaly load my data to a datagrid with one where clause condition. Then the user can change the where clause from the UI. What is happening is the first where clause on load works fine. Then when the second where clause is executed the data is added to the first local context. Is there a way to clear the local context so that when another query is performed the context does not contain the data from both?
I tried to detach the context but I'm getting an error: _context.Entry(abc).State = EntityState.Detached;
try
{
_context.myData.Where(x => x.myFlag == true).Load();
}
catch (Exception except)
{
// error
}
myVSource.Source = _context.myData.Local;
\\ then I have a click even which chnages the where clause
private void RefreshData_Click(object sender, RoutedEventArgs e)
{
_context.myData.Where(x => x.myFlag == false).Load();
}
Actually, I found a solution. In the click event, I simply added:
_context.Set().Local.ToList().ForEach(x => _context.Entry(x).State = EntityState.Detached);
before _context.myData.Where(x => x.myFlag == false).Load();
and it cleared the current data displayed.
Related
I am trying to upgrade WinForms to Telerik Controls and when I am upgrading this
this.treeAccounting.AfterSelect += new System.Windows.Forms.TreeViewEventHandler(this.TreeAccountingAfterSelect);
To this new RadControl Statement:
this.treeAccounting.SelectedNode += new Telerik.WinControls.UI.RadTreeViewEventArgs(this.TreeAccountingAfterSelect);
I get an error about best overloaded method match having invalid arguments for the TreeAccountingAfterSelect. Also it says cannot convert from 'method group' to 'Telerik.WinControls.UI.RadTreeNode'. Here is the function event for TreeAccountingAfterSelect.
private void TreeAccountingAfterSelect(object sender, Telerik.WinControls.UI.RadTreeViewEventArgs e)
{
string strSelectedNode = treeAccounting.SelectedNode.Text;
// Since the user can select any node (root, branch, leaf) of a tree in any order -
// cannot presume that they will select a root, then a leaf - so handle accordingly.
if (treeRootNames[(int)TreeNodes.TrialBalance] == strSelectedNode)
{
// Configure the Generator for doing a Trial Balance (detail) report
CrntReport = ReportTypes.TrialBalance;
CrntLocation = Locations.UNKNOWN;
// Based on default settings in the Report Property dialog (from App.Config) initialize
// screen controls.
lblCurrency.Visible = rptProperties.TBShowCurrencyCodes;
cboxCurrencyCode.Visible = rptProperties.TBShowCurrencyCodes;
this.Refresh();
// Setup the selections for the various parameters in the TrialBalance
// Parameters group.
SetupTBControls();
}
return;
}
I'm new to Telerik and I have tried different events and tried changing the parameter passed through the function and for some reason it isn't letting me use it like the WinForms. Can someone tell me where I am not understanding the change in WinForms to Telerik.
Looking at their documentation it seems that there is no SelectedNode event for a RadTreeView.
Instead you have
SelectedNodeChanged Occurs when selected node has been changed.
SelectedNodeChanging Occurs when the selected node is changing
And you don't use the RadTreeViewEventArgs to bind the event handler but a RadTreeViewEventHandler
So perhaps you need to write
this.treeAccounting.SelectedNodeChanged +=
new RadTreeViewEventHandler(this.TreeAccountingAfterSelect);
The syntax for delegate will allow also
this.treeAccounting.SelectedNodeChanged += this.TreeAccountingAfterSelect;
I'm exploring query notifications with the SQLDependency class. Building a simple working example is easy, but I feel like I'm missing something. Once I step past a simple one-table/one-dependency example I'm left wondering how can I figure out which dependency triggered my callback?
I'm having a bit of trouble explaining, so I included the simple example below. When AChange() is called I cannot look at the sql inside the dependency, and i don't have a reference to the associated cache object.
So what's a boy to do?
Option 1 - create a distinct function for each object i want to track and hard code the cache-key (or relevant information) in the callback. This feels dirty & eliminates the posibility of adding new cache items without deploying new code--ewww.
Option 2 - Use the Dependency Id property and a parallel tracking structure
Am I just missing something? Is this a deficiency in the SQLDependency structure? I've I've looked at 20 different articles on the topic and all of them seem to have the same hole. Suggestions?
Code Sample
public class DependencyCache{
public static string cacheName = "Client1";
public static MemoryCache memCache = new MemoryCache(cacheName);
public DependencyCache() {
SqlDependency.Start(connString);
}
private static string GetSQL() {
return "select someString FROM dbo.TestTable";
}
public void DoTest() {
if (memCache["TEST_KEY"] != null ) {
Debug.WriteLine("resources found in cache");
return;
}
Cache_GetData();
}
private void Cache_GetData() {
SqlConnection oConn;
SqlCommand oCmd;
SqlDependency oDep;
SqlDataReader oRS;
List<string> stuff = new List<string>();
CacheItemPolicy policy = new CacheItemPolicy();
SqlDependency.Start(connString);
using (oConn = new SqlConnection(connString) ) {
using (oCmd = new SqlCommand(GetSQL(), oConn) ) {
oDep = new SqlDependency(oCmd);
oConn.Open();
oRS = oCmd.ExecuteReader();
while(oRS.Read() ) {
resources.Add( oRS.GetString(0) );
}
oDep.OnChange += new OnChangeEventHandler (AChange);
}
}
memCache.Set("TEST_KEY", stuff, policy);
}
private void AChange( object sender, SqlNotificationEventArgs e) {
string msg= "Dependency Change \nINFO: {0} : SOURCE {1} :TYPE: {2}";
Debug.WriteLine(String.Format(msg, e.Info, e.Source, e.Type));
// If multiple queries use this as a callback how can i figure
// out WHAT QUERY TRIGGERED the change?
// I can't figure out how to tell multiple dependency objects apart
((SqlDependency)sender).OnChange -= Cache_SqlDependency_OnChange;
Cache_GetData(); //reload data
}
}
First and foremost: the handler has to be set up before the command is executed:
oDep = new SqlDependency(oCmd);
oConn.Open();
oDep.OnChange += new OnChangeEventHandler (AChange);
oRS = oCmd.ExecuteReader();
while(oRS.Read() ) {
resources.Add( oRS.GetString(0) );
}
Otherwise you have a window when the notification may be lost and your callback never invoked.
Now about your question: you should use a separate callback for each query. While this may seem cumbersome, is actually trivial by using a lambda. Something like the following:
oDep = new SqlDependency(oCmd);
oConn.Open();
oDep.OnChange += (sender, e) =>
{
string msg = "Dependency Change \nINFO: {0} : SOURCE {1} :TYPE: {2}";
Debug.WriteLine(String.Format(msg, e.Info, e.Source, e.Type));
// The command that trigger the notification is captured in the context:
// is oCmd
//
// You can now call a handler passing in the relevant info:
//
Reload_Data(oCmd, ...);
};
oRS = oCmd.ExecuteReader();
...
And remember to always check the notification source, info and type. Otherwise you run the risk of spinning ad-nauseam when you are notified for reasons other than data change, like invalid query. As a side comment I would add that a good cache design does not refresh the cache on invalidation, but simply invalidates the cached item and lets the next request actually fetch a fresh item. With your 'proactive' approach you are refreshing cached items even when not needed, refresh multiple times before they are accessed etc etc. I left out from the example error handling and proper thread synchronization (both required).
Finally, have a look at LinqtoCache which does pretty much what you're trying to do, but for LINQ queries.
I've been trying to google this but have been unable to find a solution that works for me.
I have a DataGrid that is displaying some info from a SQL table that the client dosn't know about.
The client just sends a request to the server and gets a List<SomeClass> as a response that it then displays in a DataGrid.
I need to detect when the user makes change to a row and I need the new values that the user entered.
Currently I'm using RowEditEnding event. And the method that handles this event can then:
private void editRowEventHandler(object sender, DataGridRowEditEndingEventArgs e)
{
SomeClass sClass = e.Row.DataContext as SomeClass;
// Send sClass to the server to be saved in the database...
}
This gives me the row that was being edited. But it gives me the row before the changes, and I'm unable to figure out how to get the row after the changes happen.
Is there anyone here that knows how I can do this or can point me in a direction where I might be able to find out?
See the discussion here, to avoid reading out cell-by-cell.
private void OnRowEditEnding(object sender, DataGridRowEditEndingEventArgs e)
{
DataGrid dataGrid = sender as DataGrid;
if (e.EditAction == DataGridEditAction.Commit) {
ListCollectionView view = CollectionViewSource.GetDefaultView(dataGrid.ItemsSource) as ListCollectionView;
if (view.IsAddingNew || view.IsEditingItem) {
this.Dispatcher.BeginInvoke(new DispatcherOperationCallback(param =>
{
// This callback will be called after the CollectionView
// has pushed the changes back to the DataGrid.ItemSource.
// Write code here to save the data to the database.
return null;
}), DispatcherPriority.Background, new object[] { null });
}
}
}
In your case, you are trying to detect the change in object. It comes down to the properties of the SomeClass, thus you need to focus on "Cell" instead of "Row"
Assuming your datagrid is resultGrid, i come up with the below code:
resultGrid.CellEditEnding += resultGrid_CellEditEnding;
void resultGrid_CellEditEnding(object sender, DataGridCellEditEndingEventArgs e)
{
var yourClassInstance = e.EditingElement.DataContext;
var editingTextBox = e.EditingElement as TextBox;
var newValue = editingTextBox.Text;
}
the "e" also contains information about Row and Column of the Cell. Thus you will know which editor the cell is using. In this case, i assume that it is a textbox.
Hope it help.
I asked this question in a similar post but there have been significant updates since then, but still no results so I will try to re-ask the question with the updated information.
Basically I have a pivot view with 4 pivot items. If I create the scenario where I hit the windows key then rapidly press the back key my application will reopen without reconstructing (this is the expected outcome). The functionality of the application is there. I can press application bar buttons etc.
What doesn't work is the pivot items are frozen. If I was on Pivot item A and I press the start and back button quickly I come back to Pivot Item A. If I try to switch Pivot Items, the screen does not update, its "frozen" on Pivot Item A BUT the functionality of Pivot Item B is there. (I know this because the application bar Icons for Pivot Item B are now showing).
I have read many articles on proper tombstoning scenarios and how to approach this problem. My data IS being tombstoned correctly, and upon reactivation the tombstoned data works. No objects are null so I don't have any exceptions being thrown at me.
I check to see if I need to reload the Main ViewModel (I don't need to in this case so the UI elements being created initially are not being re created).
What does fix the problem however is if the application is reconstructed. Lets say I go to the marketplace from my app, let it finish loading and press back, My application will be refreshed and working fine since it properly deactivated and reconstructed istelf. I don't rely on constructors doing all the work so I am not missing any key elements not being set when they aren't fired in the windows/back button scenario.
Does anyone have any idea why my screen would not be updating?
constructor/loaded event/on navigated to event
public MainPage()
{
InitializeComponent();
this.Loaded += new RoutedEventHandler(MainPage_Loaded);
}
private void MainPage_Loaded(object sender, RoutedEventArgs e)
{
if (App.firstTimeLoading == true)
{
App.firstTimeLoading = false;
}
BuildApplicationBar();
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
this.DataContext = App.ViewModel;
App.viewIdentifier = StringResource.MainPageView;
if (!App.ViewModel.IsDataLoaded)
{
App.ViewModel.LoadData();
String bookTitle;
App.Parser.appBookInfoDict.TryGetValue(CPlayerInventoryKeys.kInventoryKeyTitleShortTitle, out bookTitle);
PivotBackground.Title = bookTitle.ToUpper();
CreatePivotItems();
}
if (App.playerController.chapterPlayer.Source == null)
App.restoreStateClass.RestoreState();
//applies the proper background image
if (App.isDarkTheme)
{
BitmapImage bitmapImage = new BitmapImage(new Uri(StringResource.PanoramaBlackImage, UriKind.Relative));
BackgroundImage.ImageSource = bitmapImage;
BackgroundImage.Opacity = .85;
}
else
{
BitmapImage bitmapImage = new BitmapImage(new Uri(StringResource.PanoramaWhiteImage, UriKind.Relative));
BackgroundImage.ImageSource = bitmapImage;
BackgroundImage.Opacity = .5;
}
if (App.firstTimeLoading == false && PivotBackground.SelectedItem != SuggestedPivotItem)
BuildApplicationBar();
else if (PivotBackground.SelectedItem == SuggestedPivotItem)
{
BuildMarketPlaceApplicationBar();
}
base.OnNavigatedTo(e);
}
I found the answer. Since I had a media element open (play/paused) and I was implementing the "non tombstoned" method of hitting windows key and back button very quickly, the media element source was corrupt. Even though I reset this source, apparently it can be ignored and not function properly. All I had to do was add a line of code to the Application Deactivated handler.
private void Application_Deactivated(object sender, DeactivatedEventArgs e)
{
App.MainAudioPlayer.Source = null; //(only showing line added)
}
The behavior you are describing seems to be solely related to the way you are manipulating data internally and constructing your layout. I tested this both in the emulator and on a couple of physical devices, both producing normal output (even when bound to a view model).
Try creating a new Pivot-based application (without all your data - just using the default template) and see if the problem persists. Also worth mentioning - are you testing on a device or in the emulator?
Are you using transitions from the toolkit?
Are they defined in XAML?
If so that could be the issue. There's a bug which is fixed in the next version.
The solution for now is to remove the transitions or define them in code.
There is tons of information on this, but even after reading for hours and hours I can't seem to get this to work the way I want.
I'm trying to update a User object by passing in a User object and generically comparing changes to a User object I pull out of the database. I always end up getting the NotSupportedException when using this method:
An attempt has been made to Attach or
Add an entity that is not new, perhaps
having been loaded from another
DataContext. This is not supported.
Here is how I am trying to do it:
public void SaveUser(User User)
{
using (DataContext dataContext = new DataContext(WebConfigurationManager.ConnectionStrings["database"].ConnectionString))
{
// New user
if (User.UserID == 0)
{
dataContext.Users.InsertOnSubmit(User);
}
// Existing user
else
{
User dbUser = dataContext.Users.Single(u => u.UserID.Equals(User.UserID));
Type t = dbUser.GetType();
foreach (PropertyInfo p in t.GetProperties())
{
if (p.CanWrite & p.GetValue(dbUser, null) != p.GetValue(User, null))
{
p.SetValue(dbUser, p.GetValue(User, null), null);
}
}
//dataContext.Refresh(RefreshMode.KeepCurrentValues, dbUser);
}
dataContext.SubmitChanges();
}
}
The commented out line I tried uncommented too, but it was no help.
If I comment out the foreach() loop and add a line like dbUser.UserName = "Cheese"; it will update the User's name in the database fine. That leads me to believe it is something with how the foreach() loop changing the dbUser object that causes this to fail.
When I debug the dbUser object, it appears to correctly acquire all the changes from the User object that was passed as an argument.
I also did some reading on optimistic concurrency and added a column to the table of data type timestamp, but that didn't seem to have any effect either.
What exactly am I doing wrong here?
How can I get this to generically detect what has changed and correctly persist the changes to the database?
My guess is there's a foreign key relation that you are trying to copy over that was not initially loaded (because of lazy-loading) During the copying, it's attempting to load it, but the DataContext has already been disposed.
I've been working on a similar problem. I ended up using AutoMapper to handle copying the properties for me. I have configured AutoMapper to ignore the primary key field as well as any relations. Something like:
public void Update(User user)
{
using (var db = new DataContext(...))
{
var userFromDb = db.Users.Where(x => x.Id == user.Id).Single();
AutoMapper.Mapper.Map(user, userFromDb);
db.SubmitChanges();
}
}
My automapper configuration is something like
AutoMapper.Mapper.Create<User, User>().ForMember(dest => dest.Id, opt => opt.Ignore())
.ForMember(dest => dest.SomeRelation, opt => opt.Ignore());
You can find AutoMapper here: http://automapper.codeplex.com/
I keep my repo pretty lean, it's only job is to interact with the database. I build a Service layer on top of the repo that does a little more work
public class EventRepository : IEventRepository
{
private DBDataContext dc;
public EventRepository()
{
dc = new DBDataContext();
}
public void Create(Event #event)
{
dc.Events.InsertOnSubmit(#event);
}
public System.Linq.IQueryable<Event> Read()
{
object events = (from e in dc.Eventse);
return events.AsQueryable;
}
public void SubmitChanges()
{
dc.SubmitChanges();
}
}
Then the corresponding call from the service layer looks like this
public void AddEvent(Event #event)
{
_EventRepository.Create(#event);
}
public void SubmitChanges()
{
_EventRepository.SubmitChanges();
}
And I call it from my controller.
// AutoMapper will allow us to map the ViewModel with the DomainModel
Mapper.CreateMap<Domain.ViewModels.EventsAddViewModel, Domain.Event>();
object #event = Mapper.Map<Domain.ViewModels.EventsAddViewModel, Domain.Event>(eventToAdd);
// Add the event to the database
EventService.AddEvent(#event);
EventService.SubmitChanges();