I am new to entity framework,I am working on a database first scenario.
I am working through a sample crud operation and I want to delete the current object thats in the Details view.
Currently I can only delete the first object in the view
private void btnDelete_Click(object sender, RoutedEventArgs e)
{
Branch delBranch = null;
if (muTime.Branches.Count() > 0)
{
delBranch = muTime.Branches.First();
}
else
{
MessageBox.Show("No Records to delete");
return;
}
muTime.Branches.Remove(delBranch);
muTime.SaveChanges();
MessageBox.Show("Deleted " + muTime.Branches.ToString());
branchViewSource.View.Refresh();
}
You need to bring the record you want into tracking. Your current code is always going to delete the First() branch. You need to identify the control (grid?) or variable that points to the branch to delete.
private void btnDelete_Click(object sender, RoutedEventArgs e)
{
// get the id you want to delete from grid, other control or somewhere else
DataGridViewRow row = this.dataGridView1.SelectedRows[0];
var branchId = row.Cells["Id"].Value
var branchToRemove = muTime.Branches.Find(branchId); // or whatever key is
if (branchToRemove == null)
{
MessageBox.Show("No Records to delete");
return;
}
muTime.Branches.Remove(branchToRemove);
muTime.SaveChanges();
MessageBox.Show("Deleted " + branchToRemove.ToString()); // or some property that identifies?
branchViewSource.View.Refresh();
}
Related
I have a problem when deleting many nodes.
I can delete them if I select nodes like this:
But if I do something like this, I cannot delete them:
My Code:
public boolean remove(ProductNode<E> data) {
if (isEmpty()) {
throw new NoSuchElementException();
}
for (ProductNode<E> current = this.head; current != null; current = current.next) {
ProductNode<E> pre = current.prev;
ProductNode<E> next = current.next;
if (data != null) {
if (current.data.equals(data.data)) {
if (pre == null) {
head = next;
current.next = null;
} else {
if (next != null) {
next.prev = pre;
}
}
if (next == null) {
pre.next = null;
current.prev = null;
tail = pre;
} else {
if (pre != null) {
pre.next = next;
}
}
}
}
}
size--;
return false;
}
Search node
public ProductNode<E> search(E data) {
for (ProductNode<E> current = this.head; current != null; current = current.next) {
if (current.data.equals(data)) {
return current;
}
}
return null;
}
Remove
public void remove(E e) {
remove(search(e));
}
Delete:
for(Tab_Product p : remove_list){
List_Products.list_products.remove(p);
}
Your remove function (ProductNode data), is a bit complicated and may be affecting your code's ability to delete multiple nodes. In the case of this remove function you do not need traverse the whole data set. If you already have a reference to the node you can just directly modify the list with it.
public boolean remove(ProductNode<E> data) {
if (isEmpty()) {
throw new NoSuchElementException();
}
ProductNode<E> pre = data.prev;
ProductNode<E> next = data.next;
//First remove the nodes references to its neighbors.
data.prev = null;
data.next = null;
// Now check the neighbors and update their references
// to remove all references to the deleted node.
if (pre != null) pre.next = next;
if (next != null) next.prev = pre;
if (data == head) { //This checks the actual memory address.
head = next;
}
size--;
}
Since you already have the ProductNode, you do not need to search the list. your search() function is already doing that for you. since you already have the node you just need to make its references to its neighbors null then you just have to access the neighbors (if there are any) and make their old references skip over the deleted node.
I noticed a few reference errors where a deleted node was not getting completely removed from the list but i will not mention them because this delete function is rather complicated. Try simplifying the delete function and then see what your results are.
It also might be helpful if you show us the structure of the List_Products object.
Additionally you should verify that the data you select in the UI is getting passed correctly. This could be a UI bug.
I am developing Umbraco 7 MVC application and my requirement is to add Item inside Umbraco. Item name should be unique. For that used the below code but I am getting the error "Oops: this document is published but is not in the cache (internal error)"
protected override void ApplicationStarting(UmbracoApplicationBase umbracoApplication,
ApplicationContext applicationContext)
{
ContentService.Publishing += ContentService_Publishing;
}
private void ContentService_Publishing(IPublishingStrategy sender, PublishEventArgs<IContent> e)
{
try
{
if(newsItemExists)
{
e.Cancel = true;
}
}
catch (Exception ex)
{
e.Cancel = true;
Logger.Error(ex.ToString());
}
}
Then I tried adding code to unpublish but its not working i.e the node is getting published. Below is my code
private void ContentService_Publishing(IPublishingStrategy sender, PublishEventArgs<IContent> e)
{
try
{
int itemId=1234; //CurrentPublishedNodeId
if(newsItemExists)
{
IContent content = ContentService.GetById(itemId);
ContentService.UnPublish(content);
library.UpdateDocumentCache(item.Id);
}
}
catch (Exception ex)
{
e.Cancel = true;
Logger.Error(ex.ToString());
}
}
But with the above code, if you give the CurrentPublishedNodeId=2345 //someOthernodeId its unpublished correctly.
Can you please help me on this issue.
You don't have to do this, Umbraco will automatically append (1) to the name if the item already exists (so it IS unique).
If you don't want this behavior you can check in the following way:
protected override void ApplicationStarting(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
{
ContentService.Publishing += ContentService_Publishing;
}
private void ContentService_Publishing(Umbraco.Core.Publishing.IPublishingStrategy sender, PublishEventArgs<IContent> e)
{
var contentService = UmbracoContext.Current.Application.Services.ContentService;
// It's posible to batch publish items, so go through all items
// even though there might only be one in the list of PublishedEntities
foreach (var item in e.PublishedEntities)
{
var currentPage = contentService.GetById(item.Id);
// Go to the current page's parent and loop through all of it's children
// That way you can determine if any page that is on the same level as the
// page you're trying to publish has the same name
foreach (var contentItem in currentPage.Parent().Children())
{
if (string.Equals(contentItem.Name.Trim(), currentPage.Name.Trim(), StringComparison.InvariantCultureIgnoreCase))
e.Cancel = true;
}
}
}
I think your problem might be that you're not looping through all PublishedEntities but using some other way to determine the current page Id.
Note: Please please please do not use the library.UpdateDocumentCache this, there's absolutely no need, ContentService.UnPublish will take care of the cache state.
I have an ImageView and Button in an Activity, lets call it A. When clicking on the Button, I start the image gallery, where I select an image and load that into the ImageView.
On the ImageView I subscribe to the Touch events, where I want to launch another Activity, B.
My question is, how can I in Activity B get the image, which was selected in Activity A? How is data passed fomr Activity to another Activity?
Here is my code in Activity A:
protected override void OnCreate (Bundle bundle)
{
base.OnCreate (bundle);
// Set our view from the "main" layout resource
SetContentView(Resource.Layout.Main);
_imageView = FindViewById<ImageView>(Resource.Id.imageView1);
_imageView.Touch += TouchMeImageViewOnTouch;
Button button = FindViewById<Button>(Resource.Id.button1);
button.Click += ButtonOnClick;
}
private void ButtonOnClick(object sender, EventArgs eventArgs)
{
Intent = new Intent();
Intent.SetType("image/*");
Intent.SetAction(Intent.ActionGetContent);
StartActivityForResult(Intent.CreateChooser(Intent, "Select Picture"), PickImageId);
}
protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
{
if ((requestCode == PickImageId) && (resultCode == Result.Ok) && (data != null))
{
Uri uri = data.Data;
_imageView.SetImageURI(uri);
string path = GetPathToImage(uri);
Toast.MakeText(this, path, ToastLength.Long);
}
}
private string GetPathToImage(Uri uri)
{
string path = null;
string[] projection = new[] { Android.Provider.MediaStore.Images.Media.InterfaceConsts.Data };
using (var cursor = ManagedQuery(uri, projection, null, null, null))
{
if (cursor != null)
{
int columnIndex = cursor.GetColumnIndexOrThrow(
Android.Provider.MediaStore.Images.Media.InterfaceConsts.Data);
cursor.MoveToFirst();
path = cursor.GetString(columnIndex);
}
}
return path;
}
private void TouchMeImageViewOnTouch(object sender, View.TouchEventArgs touchEventArgs)
{
}
In your TouchMeImageViewOnTouch method, you will need to start Activity B. This is done by creating an Intent. This Intent can hold extra stuff the Activity you launch (B), will be able to get hold of.
So I see that you already found out how to get the path to the image, which you simply can pass along to Activity B in the Intent which is done like this:
private void TouchMeImageViewOnTouch(object sender, View.TouchEventArgs touchEventArgs)
{
var intent = new Intent(this, typeof (MainActivity));
intent.PutExtra("imagePath", path);
StartActivity(intent);
}
Then in Activity B you can get the path with:
Intent.GetStringExtra("imagePath");
Then do whatever you want with it.
I'm writing a Fragment that uses a loader to get a Cursor containing data about locations of various things on a map. I've inherited code to sort these locations by distance from the device, or from a search location; distance metrics aren't something that's particularly easy to implement in SQL, so rather than use a CursorAdapter (as elsewhere) I'm loading the data once from the Cursor and then sorting it afterwards.
I have just one problem: when the web service returns a new set of locations (for example, on first load), the list isn't updating. I've registered a ContentObserver on the Cursor and it is being hit when I call notifyChange(...) in the ContentProvider; it's just that the Cursor I've stored from the original load still has a count of zero.
The callbacks and the ContentObserver look like this:
private LoaderCallbacks<Cursor> mCallbacks = new LoaderCallbacks<Cursor>() {
public void onLoaderReset(Loader<Cursor> loader) {
mLoaderCreated = false;
mCursor.unregisterContentObserver(mObserver);
mCursor = null;
}
public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
if(cursor!=mCursor) {
if(mCursor!=null)
mCursor.unregisterContentObserver(mObserver);
cursor.registerContentObserver(mObserver);
mCursor = cursor;
if(cursor.isClosed()) {
getLoaderManager().restartLoader(mFragmentId, null, mCallbacks);
return;
}
}
mDataModel.populate(cursor);
}
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
mLoaderCreated = true;
triggerServicesFeed();
CursorLoader cursorLoader = null;
if(id == mFragmentId) {
cursorLoader = new CursorLoader(getActivity(),
FerrariVertuContentProvider.SERVICES_URI,
null, null, null,null);
}
return cursorLoader;
}
};
private ContentObserver mObserver = new ContentObserver(null) {
public void onChange(boolean selfChange, android.net.Uri uri) {
onChange(selfChange);
};
public void onChange(boolean selfChange) {
if(mCursor.isClosed()) {
mCursor.unregisterContentObserver(this);
mCursor = null;
} else {
getActivity().runOnUiThread(new Runnable() {
#Override
public void run() {
//mCursor still reports zero on first run
mDataModel.populate(mCursor);
}
});
}
};
};
I know CursorAdapter just updates when the Cursor updates, and the fact that I'm getting update events when I'd expect to makes me think this stage of the process, at least, is working. How do I either get mCursor to give me the new data, or get a fresh Cursor representing the new data?
`hi
I am doing a simple synchronous socket programming,in which i employed twothreads
one for accepting the client and put the socket object into a collection,other thread will
loop through the collection and send message to each client through the socket object.
the problem is
1.i connect to clients to the server and start send messages
2.now i want to connect a new client,while doing this i cant update the collection and add
a new client to my hashtable.it raises an exception "collection modified .Enumeration operation may not execute"
how to add a NEW value without having problems in a hashtable.
private void Listen()
{
try
{
//lblStatus.Text = "Server Started Listening";
while (true)
{
Socket ReceiveSock = ServerSock.Accept();
//keys.Clear();
ConnectedClients = new ListViewItem();
ConnectedClients.Text = ReceiveSock.RemoteEndPoint.ToString();
ConnectedClients.SubItems.Add("Connected");
ConnectedList.Items.Add(ConnectedClients);
ClientTable.Add(ReceiveSock.RemoteEndPoint.ToString(), ReceiveSock);
//foreach (System.Collections.DictionaryEntry de in ClientTable)
//{
// keys.Add(de.Key.ToString());
//}
//ClientTab.Add(
//keys.Add(
}
//lblStatus.Text = "Client Connected Successfully.";
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
private void btn_receive_Click(object sender, EventArgs e)
{
Thread receiveThread = new Thread(new ThreadStart(Receive));
receiveThread.IsBackground = true;
receiveThread.Start();
}
private void Receive()
{
while (true)
{
//lblMsg.Text = "";
byte[] Byt = new byte[2048];
//ReceiveSock.Receive(Byt);
lblMsg.Text = Encoding.ASCII.GetString(Byt);
}
}
private void btn_Send_Click(object sender, EventArgs e)
{
Thread SendThread = new Thread(new ThreadStart(SendMsg));
SendThread.IsBackground = true;
SendThread.Start();
}
private void btnlist_Click(object sender, EventArgs e)
{
//Thread ListThread = new Thread(new ThreadStart(Configure));
//ListThread.IsBackground = true;
//ListThread.Start();
}
private void SendMsg()
{
while (true)
{
try
{
foreach (object SockObj in ClientTable.Keys)
{
byte[] Tosend = new byte[2048];
Socket s = (Socket)ClientTable[SockObj];
Tosend = Encoding.ASCII.GetBytes("FirstValue&" + GenerateRandom.Next(6, 10).ToString());
s.Send(Tosend);
//ReceiveSock.Send(Tosend);
Thread.Sleep(300);
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
}
You simply can't modify a Hashtable, Dictionary, List or anything similar while you're iterating over it - whether in the same thread or a different one. There are concurrent collections in .NET 4 which allow this, but I'm assuming you're not using .NET 4. (Out of interest, why are you still using Hashtable rather than a generic Dictionary?)
You also shouldn't be modifying a Hashtable from one thread while reading from it in another thread without any synchronization.
The simplest way to fix this is:
Create a new readonly variable used for locking
Obtain the lock before you add to the Hashtable:
lock (tableLock)
{
ClientTable.Add(ReceiveSock.RemoteEndPoint.ToString(), ReceiveSock);
}
When you want to iterate, create a new copy of the data in the Hashtable within a lock
Iterate over the copy instead of the original table
Do you definitely even need a Hashtable here? It looks to me like a simple List<T> or ArrayList would be okay, where each entry was either the socket or possibly a custom type containing the socket and whatever other information you need. You don't appear to be doing arbitrary lookups on the table.
Yes. Don't do that.
The bigger problem here is unsafe multi-threading.
The most basic "answer" is just to say: use a synchronization lock on the shared object. However this hides a number of important aspects (like understanding what is happening) and isn't a real solution to this problem in my mind.