I am working on a project where I read some hardware data from via USB and I need to save the state to a database every second. I want to do this via LINQ, however it seems not to work. It fails to submit changes to database. Any help would be much appreciated.
private string connString = "someConnectionString";
private BMSDataContext BMS_DS;
private USBConnection USBConn;
protected override void OnStart(string[] args)
{
//Connecting to USB device
USBConn = new USBConnection();
USBConn.attemptUSBConnection();
if (USBConn.getConnectionStatus())
EventLog.WriteEntry("Successfully Connected to USB device", EventLogEntryType.Information);
else
EventLog.WriteEntry("Failed to connect to USB device", EventLogEntryType.Error);
//initialing the DataContext
BMS_DS = new BMSDataContext(connString);
System.Timers.Timer timer = new System.Timers.Timer(5000);
timer.Elapsed += new System.Timers.ElapsedEventHandler(this.ReadFromUSBAndLog);
timer.Start();
}
private void ReadFromUSBAndLog(object sender, System.Timers.ElapsedEventArgs e)
{
if (!USBConn.getConnectionStatus())
EventLog.WriteEntry("Connection to USB lost!", EventLogEntryType.Error);
//reading data via USB
USBConn.receiveViaUSB();
testLog newRow = new testLog
{
value = USBConn.fromDeviceToHostBuffer[1].ToString()
};
//THIS IS AS FAR AS IT GOES...
BMS_DS.testLogs.InsertOnSubmit(newRow);
//THIS IS NEVER REACHED
BMS_DS.SubmitChanges();
EventLog.WriteEntry("Submitted", EventLogEntryType.Information);
}
OK I was being stupid. It seems that my test table didn't have a Primary Key and the insert was failing because of it. I didn't know this was a requirement. Working fine after adding a identity pk column to the table.
Thanks
Related
I've been trying to connect to a specific wifi through code, but with no succcess.
This is what i've come up with:
public void ConnectToWifi(string ssid, string password)
{
WifiManager wifiManager = (WifiManager)Android.App.Application.Context.GetSystemService(Context.WifiService);
if (!wifiManager.IsWifiEnabled)
{
wifiManager.SetWifiEnabled(true);
}
string formattedSsid = $"\"{ssid}\"";
string formattedPassword = $"\"{password}\"";
WifiConfiguration wifiConfig = new WifiConfiguration
{
Ssid = formattedSsid,
PreSharedKey = formattedPassword
};
var addNetwork = wifiManager.AddNetwork(wifiConfig);
WifiConfiguration network = wifiManager.ConfiguredNetworks.FirstOrDefault(n => n.Ssid == ssid);
if (network == null)
{
Console.WriteLine($"Cannot connect to network: {ssid}");
return;
}
wifiManager.Disconnect();
bool enableNetwork = wifiManager.EnableNetwork(network.NetworkId, true);
}
I've added permissions.
When testing it does turn the wifi on atleast, so i know it works until that point. What seems not to be working is the AddNetwork part.
I appreciate any help i can get!
You are missing one key method - reconnect(). You can read more about it in the WifiManager's docs here
The important part of the documentation is:
Reconnect to the currently active access point, if we are currently disconnected.
So, what you need to do it after you have disconnected and enabled your new network, call in the end this and you will be good to go:
wifiManager.Disconnect();
wifiManager.EnableNetwork(network.NetworkId, true);
wifiManager.Reconnect(); // This is the missing method
NB: Keep in mind that most of the WifiManager's code that you are using is being obsolete starting Android 10. So, if you want to target Android 10, then you will need to write an additional code for the connectivity for devices with Android 10+.
System-Environment:
Windows 10 Pro - Version: 1909 - OS System Build: 18363.752
Microsoft Outlook 2019 MSO - Version 1808 - 32-Bit
Microsoft Exchange 2016 15.1 Build (Build 1979.3)
-- Microsoft Exchange is installed on Microsoft Server 2016
Outlook Redemption COM-Library - Version 5.22.0.5498
Issue Summary:
The application sends emails via Outlook using the Outlook-Redemption COM-Library. The class "RedemptionHandler" is our Singleton-Class which interacts with the Outlook-Redemption COM-Library. During the construction of the RedemptionHandler we create a RDOSession with a static class named RedemptionLoader and call Logon() on the RDOSession. The RDOSession is used afterwards in Initialize() to retrieve the Folders for Drafts and mails which are sent.
public static class RedemptionLoader
{
public static RDOSession new_RDOSession()
{
return (RDOSession)NewRedemptionObject(new Guid("29AB7A12-B531-450E-8F7A-EA94C2F3C05F"));
}
}
public class RedemptionHandler
{
private static RedemptionHandler instance = null;
private static readonly object padlock = new object();
private RDOSession _rdoSession;
private RDOFolder _rdoSentFolder;
private RDOFolder _rdoDraftsFolder;
private RDOItems _sentItems = null;
public EventHandler<MailGesendetEventArgs> MailSuccessfullySent;
private RedemptionHandler()
{
_rdoSession = RedemptionLoader.new_RDOSession();
_rdoSession.Logon(null, null, false, null, null, null);
Initialize();
}
public static RedemptionHandler Instance
{
get
{
lock (padlock)
{
if (instance == null)
{
instance = new RedemptionHandler();
}
return instance;
}
}
}
private void Initialize()
{
try
{
if (isInitialized) return;
_rdoSentFolder = _rdoSession.GetDefaultFolder(Redemption.rdoDefaultFolders.olFolderSentMail);
_sentItems = _rdoSentFolder.Items;
_sentItems.ItemAdd += MailSent;
_rdoDraftsFolder = _rdoSession.GetDefaultFolder(Redemption.rdoDefaultFolders.olFolderDrafts);
isInitialized = true;
}
catch
{
//TODO
isInitialized = false;
}
}
}
At this point, we have a working instance from our RedemptionHandler. The COM-Object RDOSession is created and referenced within just as the RDOFolder for Drafts and Sent. We have also registrered an event-listener for the Sent-Folder to recognize new Mails in this folder.
In the next steps we want to send an email and recognize this email if its stored in the sent-folder. We use the RDOMail.Fields - Property to store custom data within the RDOMail-Object.
public RDOMail CreateMail(string recipient, string subject, string body, Guid gdSender, string storagePath)
{
RDOMail newMail = _rdoDraftsFolder.Items.Add(Redemption.rdoItemType.olMailItem);
newMail.Recipients.Add(recipient);
newMail.Recipients.ResolveAll();
newMail.Subject = subject;
newMail.HTMLBody = body;
newMail.BodyFormat = (int)rdoBodyFormat.olFormatHTML;
// Here we want to store an identifier in the RDOMail.Fields
int id = newMail.GetIDsFromNames(PropertyGuid, PropertyGdItemId);
newMail.Fields[id] = Guid.NewGuid().ToString();
return newMail;
}
After the mail creation we want to display the mail to the user because we dont want to send data without letting the user know about it.
public void DisplayMail(RDOMail mail, bool modal = false)
{
mail.Display(modal, null);
}
The Outlook window now comes to front and the user checks the mail and clicks on send.
The Mail is now stored in the Sent-Folder.
The MailSent Event gets invoked by the RDOFolder.Items.Add Listener.
private void MailSent(RDOMail mail)
{
var test = mail.Fields[SenderId];
Console.WriteLine(test);
// test value is correct!
}
Difference between Exchange in Online-Mode and Cache-Mode:
If we use the Exchange with Cache-Mode, everything works fine. Everytime we send an email, the MailSent is triggered and we can read data from the RDOMail.Fields-Property. If we switch to Exchange without Cache, the MailSent Event is triggered only once, when the first mail is sent. All emails afterwars are sent but dont trigger the MailSent-Event. If we delete this line of code, everything works also fine without Cache-Mode.
var test = mail.Fields[SenderId];
This is because we think that reading data from the RDOMail.Fields - Property does something special if the cache-mode from exchange is deactivated.
We need to store custom data within the mails to check if new mails in the sent-folder are created by our application or not.
We highly appreciate help and hints.
I tried to fix this issue without success. I've set-up a new Project without any other code:
public partial class RedemptionTest : Form
{
static RDOSession _rdoSession;
static RDOFolder _rdoSentFolder;
static RDOFolder _rdoDraftsFolder;
static RDOItems _draftItems;
static RDOItems _sentItems;
public RedemptionTest()
{
InitializeComponent();
}
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
_rdoSession = RedemptionLoader.new_RDOSession();
_rdoSession.Logon();
_rdoSentFolder = _rdoSession.GetDefaultFolder(rdoDefaultFolders.olFolderSentMail);
_rdoDraftsFolder = _rdoSession.GetDefaultFolder(rdoDefaultFolders.olFolderDrafts);
_sentItems = _rdoSentFolder.Items;
_draftItems = _rdoDraftsFolder.Items;
_draftItems.ItemAdd += DraftAdd;
_sentItems.ItemAdd += MailSent;
}
private void DraftAdd(RDOMail Item)
{
Console.WriteLine(Item.Subject);
}
private void MailSent(RDOMail Item)
{
Console.WriteLine(Item.Subject);
}
}
The Drafts-Folder Event is fired all the time, the MailSent Event is only fired the first time. I have stored all RDO-Objects in static variables to avoid them from being garbage collected.
The object raising the events (RDOItems) must be alive be able to fire the events. Your code is using multiple dot notation, which means the compiler creates an implicit variable to hold the RDOItems collection. As soon as that variable is released by the Garbage Collector, no events will be fired.
The line
_rdoSentFolder.Items.ItemAdd += MailSent;
must be changed to
RDOItems _sentItems; //global/class variable
..
_sentItems = _rdoSentFolder.Items;
_sentItems .ItemAdd += MailSent;
Have the same issue in Outlook VSTO add-in using Redemption. Happens for both Sent and Inbox folder. The same code works correctly in cached mode but fires events only once in Online mode.
Native Outlook object model Items.ItemAdd works correctly in Online mode for the same folder.
Currently, we were able to do a workaround for this by unsubscribing and resubscribing to event right in the event handler. Like this:
private void SentItems_ItemAdd(RDOMail rdoMail)
{
_sentItems.ItemAdd -= SentItems_ItemAdd;
_sentItems.ItemAdd += SentItems_ItemAdd;
Log.Debug("SentItems.ItemAdd");
SentMailItemAdd?.Invoke(rdoMail);
}
I am currently using the Event Store to handle my events. I currently need to replay a particular type of event as I have made changes in the way they are subscribed and written to DB.
Is this possible? If so, how can it be done? Thanks.
You cannot tell EventStore to replay a specific event onto a persistent subscription because the point of the persistent subscription is to keep state for the subscribers.
To achieve this kind of fix you would really need a catch up application to do the work.
And really if you think about, if you replayed ALL the events to a new database then you would have the correct data in there?
So I have a console application that reuses the same logic as the persistent connection but the only difference is:
I change the target database connection string - So this would be a new Database or Collection (not the broken one)
It connects to EventStore and replays all the events from the start
It rebuilds the entire database to the correct state
Switch the business over to the new database
This is the point of EventStore - You just replay all the events to build any database at any time and it will be correct
Your persistent connections deal with new, incoming events and apply updates.
If you enable $by_event_type projection than you can access that projection stream under
/streams/$et-{event-type}
https://eventstore.org/docs/projections/system-projections/index.html
Then you can read it using .net api if you wish.
Here is some code to get you started
private static T GetInstanceOfEvent<T>(ResolvedEvent resolvedEvent) where T : BaseEvent
{
var metadataString = Encoding.UTF8.GetString(resolvedEvent.Event.Metadata);
var eventClrTypeName = JObject.Parse(metadataString).Property(EventClrTypeHeader).Value;
var #event = JsonConvert.DeserializeObject(Encoding.UTF8.GetString(resolvedEvent.Event.Data), Type.GetType((string) eventClrTypeName));
if (!(#event is BaseEvent))
{
throw new MessageDeserializationException((string) eventClrTypeName, metadataString);
}
return #event as T;
}
private static IEventStoreConnection GetEventStoreConnection()
{
var connectionString = System.Configuration.ConfigurationManager.ConnectionStrings["EventStore"].ConnectionString;
var connection = EventStoreConnection.Create(connectionString);
connection.ConnectAsync().Wait();
return connection;
}
private static string GetStreamName<T>() where T : BaseEvent
{
return "$et-" + typeof(T).Name;
}
And to read events you can use this code snippet
StreamEventsSlice currentSlice;
long nextSliceStart = StreamPosition.Start;
const int sliceCount = 200;
do
{
currentSlice = await esConnection.ReadStreamEventsForwardAsync(streamName, nextSliceStart, sliceCount, true);
foreach (var #event in currentSlice.Events)
{
var myEvent = GetInstanceOfEvent<OrderMerchantFeesCalculatedEvent>(#event);
TransformEvent(myEvent);
}
nextSliceStart = currentSlice.NextEventNumber;
} while (currentSlice.IsEndOfStream == false);
My application is completely based on internet and it does not work without it, when the internet is not available or it is slow my application is getting stopped unfortunately.
I tried to implement try, catch but it is not helping me out as it is not throwing any exception, then I thought that I have to check the internet connectivity continuously till the app is running and stop any activity from performing and set a popup to connect to the internet.
I am able to get the popup whenever I call a method which has the following code inside it,
ConnectivityManager connectivityManager = (ConnectivityManager)GetSystemService(ConnectivityService);
NetworkInfo networkInfo = connectivityManager.ActiveNetworkInfo;
if (networkInfo == null)
{
AlertDialog.Builder alert = new AlertDialog.Builder(this);
alert.SetTitle("Network");
alert.SetMessage("Please turn of your Wifi or Mobile Data From Settings");
alert.SetPositiveButton("OK", (senderAlert, args) => {
Intent intent = new Intent(Android.Provider.Settings.ActionSettings);
StartActivity(intent);
});
alert.SetNegativeButton("Cancel", (senderAlert, args) => {
Toast.MakeText(this, "Cancelled!", ToastLength.Short).Show();
Finish();
});
Dialog dialog = alert.Create();
dialog.Show();
But I am unable to get the connection checked continuously, So Can some one Please help me to complete get this functionality in my application.
You need to use a BroadcastReceiver to monitor network changes.
[BroadcastReceiver(Enabled = true)]
[IntentFilter(new[] { "android.net.conn.CONNECTIVITY_CHANGE" })]
[Android.Runtime.Preserve(AllMembers = true)]
public class ConnectivityChangeBroadcastReceiver : BroadcastReceiver
{
public override void OnReceive(Context context, Intent intent)
{
if (intent.Action != ConnectivityManager.ConnectivityAction)
return;
//Check if is connected and raise a custom event or store
//the current in a static global variable
}
}
}
In Android 7.0, you need to remove IntentFilter from the class and register the receiver.
var receiver = new ConnectivityChangeBroadcastReceiver();
Application.Context.RegisterReceiver(receiver, new IntentFilter(ConnectivityManager.ConnectivityAction));
Another option is to use the ConnectivityPlugin https://github.com/jamesmontemagno/ConnectivityPlugin , which is easier to use.
CrossConnectivity.Current.ConnectivityChanged += HandleConnectivityChanged;
void HandleConnectivityChanged (object sender, ConnectivityChangedEventArgs e)
{
// You can check the network status in
//e.IsConnected
}
Note that The ACCESS_NETWORK_STATE and ACCESS_WIFI_STATE permissions are required.
When data is entered, it ultimately needs to be saved remotely on a server. I do want the app to work if there is no data connection at the time also, so I need to save everything locally on the phone too. The app can then sync with the server when it gets a connection.
This brings up a little issue. I'm used to saving everything on the server and then getting the records back with id's generated from the server for them. If there is no connection, the app will save locally to the phone but not the server. When syncing with the server, I don't see a way for the phone to know when a record comes back which locally record it's associated with. There isn't enough unique data to figure this out.
What is the best way to handle this?
One way I've been thinking is to change the id of the records to a GUID and let the phone set the id. This way, all records will have an id locally, and when saving to the server, it should still be a unique id.
I'd like to know what other people have been doing, and what works and what doesn't from experience.
This is how we done with a first windows phone 7 app finished few days ago with my friend.
It might not be the best solution but 'till additional refactoring it works just fine.
It's an application for a web app like a mint.com called slamarica.
If we have feature like save transaction, we first check if we have connection to internet.
// Check if application is in online or in offline mode
if (NetworkDetector.IsOnline)
{
// Save through REST API
_transactionBl.AddTransaction(_currentTransaction);
}
else
{
// Save to phone database
SaveTransactionToPhone(_currentTransaction);
}
If transaction is successfully saved via REST, it responses with transaction object and than we save it to local database. If REST save failed we save data to local database.
private void OnTransactionSaveCompleted(bool isSuccessful, string message, Transaction savedTransaction)
{
MessageBox.Show(message);
if(isSuccessful)
{
// save new transaction to local database
DatabaseBl.Save(savedTransaction);
// save to observable collection Transactions in MainViewModel
App.ViewModel.Transactions.Add(App.ViewModel.TransactionToTransactionViewModel(savedTransaction));
App.ViewModel.SortTransactionList();
// Go back to Transaction List
NavigationService.GoBack();
}
else
{
// if REST is failed save unsent transaction to Phone database
SaveTransactionToPhone(_currentTransaction);
// save to observable collection Transactions in MainViewModel
App.ViewModel.Transactions.Add(App.ViewModel.TransactionToTransactionViewModel(_currentTransaction));
App.ViewModel.SortTransactionList();
}
}
Every Transaction object has IsInSync property. It is set to false by default until we got confirmation from REST API that it's saved successful on the server.
User has ability to refresh transactions. User can click on a button Refresh to fetch new data from the server. We do the syncing in the background like this:
private void RefreshTransactions(object sender, RoutedEventArgs e)
{
if (NetworkDetector.IsOnline)
{
var notSyncTransactions = DatabaseBl.GetData<Transaction>().Where(x => x.IsInSync == false).ToList();
if(notSyncTransactions.Count > 0)
{
// we must Sync all transactions
_isAllInSync = true;
_transactionSyncCount = notSyncTransactions.Count;
_transactionBl.AddTransactionCompleted += OnSyncTransactionCompleted;
if (_progress == null)
{
_progress = new ProgressIndicator();
}
foreach (var notSyncTransaction in notSyncTransactions)
{
_transactionBl.AddTransaction(notSyncTransaction);
}
_progress.Show();
}
else
{
// just refresh transactions
DoTransactionRefresh();
}
}
else
{
MessageBox.Show(ApplicationStrings.NETWORK_OFFLINE);
}
}
private void DoTransactionRefresh()
{
if (_progress == null)
{
_progress = new ProgressIndicator();
}
// after all data is sent do full reload
App.ViewModel.LoadMore = true;
App.ViewModel.ShowButton = false;
ApplicationBl<Transaction>.GetDataLoadingCompleted += OnTransactionsRefreshCompleted;
ApplicationBl<Transaction>.GetData(0, 10);
_progress.Show();
}
OnTransactionRefreshCompleted we delete all transaction data in local database and get the latest 10 transactions. We don't need all the data, and this way user have synced data. He can always load more data by taping load more at the end of transaction list. It's something similar like those twitter apps.
private void OnTransactionsRefreshCompleted(object entities)
{
if (entities is IList<Transaction>)
{
// save transactions
var transactions = (IList<Transaction>)entities;
DatabaseBl.TruncateTable<Transaction>();
DatabaseBl.Save(transactions);
((MainViewModel) DataContext).Transactions.Clear();
//reset offset
_offset = 1;
//update list with new transactions
App.ViewModel.LoadDataForTransactions(transactions);
App.ViewModel.LoadMore = false;
App.ViewModel.ShowButton = true;
}
if (entities == null)
{
App.ViewModel.ShowButton = false;
App.ViewModel.LoadMore = false;
}
// hide progress
_progress.Hide();
// remove event handler
ApplicationBl<Transaction>.GetDataLoadingCompleted -= OnTransactionsRefreshCompleted;
}
Caveat - I haven't tried this with windows phone development but use of GUID identities is something I usually do when faced with similar situations - eg creating records when I only have a one-way connection to the database - such as via a message bus or queue.
It works fine, albeit with a minor penalty in record sizes, and can also cause less performant indexes. I suggest you just give it a shot.