I need to run a raw sql query, but I'm getting an error when I try to open the connection to the database. "The connection was not closed. The connection's current state is open."
_loginValidator and _contactService are passed into the controller through DI:
services.AddScoped<ILoginValidator, LoginValidator>();
services.AddScoped<IContactService, ContactService>();
The two lines below are in an action function of the controller. If I switch the two lines, the error goes away...:
var validationErrors = _loginValidator.Validate(id, "");
var user = _contactService.GetContact(id);
Here is _loginValidator.Validate. If I comment out the second line, the error goes away...:
public LoginValidationResult Validate(int userId, string encryptedPassword)
{
var vr = new LoginValidationResult();
var user = _context.Users.Include(u => u.LoginUserQuestionAnswers).FirstOrDefault(u => u.Id == userId);
//...
}
Here is _contactService.GetContact. This is where I get the error:
public ContactDto GetContact(int id)
{
var conn = _context.Database.GetDbConnection();
//ERROR HERE!!!
conn.Open();
//work on conn, for example: ExecuteReader
conn.Close();
}
Notes:
If I comment out the _context line in the Validate(...) function, I do not get the error.
If I switch the two lines I listed in the action function, I do not get the error.
I think the problem is that EntityCore is not closing the connection after I finish using it in _loginValidator.Validate(...)
Anyone know how I can deal with this problem?
DB Connection is an unmanaged resource and you need to close it yourself. The best practice is to use a using statement for your DB connections.
See these links:
http://stackoverflow.com/questions/35077000/entity-framework-7-get-database-time
https://msdn.microsoft.com/en-us/data/dn456849.aspx
The connection being left open after the FirstOrDefault query is a bug. I filed https://github.com/aspnet/EntityFramework/issues/6581 for it and we just triaged it for the 1.0.2 release.
To workaround the bug for now I think you can check if the connection is already open and, if so, don't try to open it again.
Related
I use SignalR in an Angular app. When I destroy component in Angular I also want to stop connection to the hub. I use the command:
this.hubConnection.stop();
But I get an error in Chrome console:
Websocket closed with status code: 1006
In Edge: ERROR Error: Uncaught (in promise): Error: Invocation canceled due to connection being closed. Error: Invocation canceled due to connection being closed.
It actually works and connection has been stopped, but I would like to know why I get the error.
This is how I start the hub:
this.hubConnection = new HubConnectionBuilder()
.withUrl("/matchHub")
.build();
this.hubConnection.on("MatchUpdate", (match: Match) => {
// some magic
})
this.hubConnection
.start()
.then(() => {
this.hubConnection.invoke("SendUpdates");
});
EDIT
I finally find the issue. Its caused by change streams from Mongo. If I remove the code from SendUpdates() method then OnDisconnected is triggered.
public class MatchHub : Hub
{
private readonly IMatchManager matchManager;
public MatchHub(IMatchManager matchManager)
{
this.matchManager = matchManager;
}
public async Task SendUpdates() {
using (var changeStream = matchManager.GetChangeStream()) {
while (changeStream.MoveNext()) {
var changeStreamDocument = changeStream.Current.FullDocument;
if (changeStreamDocument == null) {
changeStreamDocument = BsonSerializer.Deserialize<Match>(changeStream.Current.DocumentKey);
}
await Clients.Caller.SendAsync("MatchUpdate", changeStreamDocument);
}
}
}
public override async Task OnDisconnectedAsync(Exception exception)
{
await base.OnDisconnectedAsync(exception);
}
}
Method GetChangeStream from the manager.
ChangeStreamOptions options = new ChangeStreamOptions() { FullDocument = ChangeStreamFullDocumentOption.UpdateLookup };
var watch = mongoDb.Matches.Watch(options).ToEnumerable().GetEnumerator();
return watch;
But I don't know how to fix it.
This can be for many reasons but i think it is most likely this one:
I think this is because of how the server is handling the connected / disconnected events. I can't say for sure but the connection closing needs to handled correctly on the server also with code. Try overriding the built in On Connected /Disconnected methods on the server and see. My assumption only is that you're closing it but the server isn't closing properly and therefore not relaying the proper closed response.
found as a comment at : getting the reason why websockets closed with close code 1006
Where you don't need to change the connection/disconection because evrything works fine. But as an answer this one is the most likely.
It throws error because the callback doesn't get clear properly.
And it is caused by the return data from websocket.
normally it should return like
However, for some reason it might return something like
the very last response breaking into 2 pieces
And that causes the issue.
I don't think there is a way to bypass this without changing the source code.
I reported this on github repo as well at here
It turns out that I can just utilize invocation response to notify client to stop the hub. So it doesn't trigger racing issue.
I have created an application for FIX transactions using QuickFIX c++ API. The application is connecting to the server but the server sends "Provide UserName<553>" message. I looked for and result and found that i need to add username and password to the toAdmin method created this following code to in order to achieve that
void Application::toAdmin( FIX::Message& message, const FIX::SessionID& sessionID)
{
if (FIX::MsgType_Logon == message.getHeader().getField(FIX::FIELD::MsgType))
{
FIX44::Logon& logon_message = dynamic_cast<FIX44::Logon&>(message);
logon_message.setField(FIX::Username("my_username"));
logon_message.setField(FIX::Password("my_password"));
}
}
But then it throws and Exception. Please suggest what to do
remove this line and exception is handled
FIX44::Logon& logon_message = dynamic_cast<FIX44::Logon&>(message);
after that Put it
message.setField(FIX::Username("my_username"));
```````
message.setField(FIX::Password("my_password"));
After executing the Command using SqlDataAdapter, connection with the db is not getting closed. Let me know what needs to be done. Here is the code snippet
DataSet dsResult = new DataSet("Result");
SqlCommand selectCommand = new SqlCommand();
if (_datasource.DataType == DataType.SqlText)
{
selectCommand = GenerateCommand(_datasource.DataType,_sqlquery);
}
else
{
selectCommand = GenerateCommand(_datasource.DataType, _datasource.DataObjectName, _fieldNames, _filters);
}
SqlDataAdapter da = new SqlDataAdapter(selectCommand.CommandText, _datasource.ConnectionString);
da.Fill(dsResult);
dataset = dsResult;
Tried explicity closing the connection like da.SelectCommand.Connection.Close(). But issue did not get fixed.
Also tried the following still issue not fixed
using(SqlDataAdapter da = new SqlDataAdapter(selectCommand.CommandText, _datasource.ConnectionString))
{
da.Fill(dsResult);
}
Let me know what can be done to release the session.
The Fill method retrieves rows from the data source using the SELECT
statement specified by an associated SelectCommand property. The
connection object associated with the SELECT statement must be valid,
but it does not need to be open. If the connection is closed before
Fill is called, it is opened to retrieve data, then closed. If the
connection is open before Fill is called, it remains open.
http://msdn.microsoft.com/en-us/library/377a8x4t.aspx
I highlighted you case. You haven't opened the connection, so the DataAdapter will open it automatically for you and close it when it's finished.
Edit: If you want to manage the connection yourself, you should always close it immediately you're finished with it.
Therefor you could use the using-statement which disposes/closes it (even in case of an exception).
using(var con = new SqlConnection(_datasource.ConnectionString))
{
using(var da = new SqlDataAdapter(selectCommand.CommandText, con))
{
con.Open(); // not needed but ...
da.Fill(dsResult); // will not close the conection now
}
} // will close the connection
Edit2: Closing a conection does not mean that it is closed physically. It is just a hint for the Connection-Pool that it can be used again.
ExecuteReader requires an open and available Connection. The connection's current state is Connecting
The error above occurs when I try to do a dataReader.Read on the data recieved from the database. I know there are two rows in there so it isnt because no data actually exists.
Could it be the CommandBehavior.CloseConnection, causing the problem? I was told you had to do this right after a ExecuteReader? Is this correct?
try
{
_connection.Open();
using (_connection)
{
SqlCommand command = new SqlCommand("SELECT * FROM Structure", _connection);
SqlDataReader dataReader = command.ExecuteReader(CommandBehavior.CloseConnection);
if (dataReader == null) return null;
var newData = new List<Structure>();
while (dataReader.Read())
{
var entity = new Structure
{
Id = (int)dataReader["StructureID"],
Path = (string)dataReader["Path"],
PathLevel = (string)dataReader["PathLevel"],
Description = (string)dataReader["Description"]
};
newData.Add(entity);
}
dataReader.Close();
return newData;
}
}
catch (SqlException ex)
{
AddError(new ErrorModel("An SqlException error has occured whilst trying to return descendants", ErrorHelper.ErrorTypes.Critical, ex));
return null;
}
catch (Exception ex)
{
AddError(new ErrorModel("An error has occured whilst trying to return descendants", ErrorHelper.ErrorTypes.Critical, ex));
return null;
}
finally
{
_connection.Close();
}
}
Thanks in advance for any help.
Clare
When you use the Using in C#, after the last } from the using, the Connection automatically close, thats why you get the fieldcount to be closed when u try to read him, as that is impossible, because u want those datas, read then before close the using, or u can open and close manually the connection, by not using the (using)
Your code, as displayed is fine. I've taken it into a test project, and it works. It's not immediately clear why you get this message with the code shown above. Here are some debugging tips/suggestions. I hope they're valuable for you.
Create a breakpoint on the while (dataReader.Read()). Before it enters its codeblock, enter this in your Immediate or Watch Window: dataReader.HasRows. That should evaluate to true.
While stopped on that Read(), open your Locals window to inspect all the properties of dataReader. Ensure that the FieldCount is what you expect from your SELECT statement.
When stepping into this Read() iteration, does a student object get created at all? What's the value of dataReader["StructureID"] and all others in the Immediate Window?
It's not the CommandBehavior.CloseConnection causing the problem. That simply tells the connection to also close itself when you close the datareader.
When I got that error, it happened to be a command timeout problem (I was reading some large binary data). As a first attempt, I increased the command timeout (not the connection timeout!) and the problem was solved.
Note: while attempting to find out the problem, I tried to listen to the (Sql)connection's StateChanged event, but it turned out that the connection never fall in a "broken" state.
Same problem here. Tested all the above solutions
increase command timeout
close the connection after read
Here's the code
1 objCmd.Connection.Open()
2 objCmd.CommandTimeout = 3000
3 Dim objReader As OleDbDataReader = objCmd.ExecuteReader()
4 repeater.DataSource = objReader
5 CType(repeater, Control).DataBind()
6 objReader.Close()
7 objCmd.Connection.Dispose()
Moreover, at line 4 objReader has Closed = False
I got this exception while using the VS.NET debugger and trying to examine some IQueryable results. Bad decision because the IQueryable resulted in a large table scan. Stopping and restarting the debugger and NOT trying to preview this particular IQueryable was the workaround.
We require programmatic access to a SQL Server Express service as part of our application. Depending on what the user is trying to do, we may have to attach a database, detach a database, back one up, etc. Sometimes the service might not be started before we attempt these operations. So we need to ensure the service is started. Here is where we are running into problems. Apparently the ServiceController.WaitForStatus(ServiceControllerStatus.Running) returns prematurely for SQL Server Express. What is really puzzling is that the master database seems to be immediately available, but not other databases. Here is a console application to demonstrate what I am talking about:
namespace ServiceTest
{
using System;
using System.Data.SqlClient;
using System.Diagnostics;
using System.ServiceProcess;
using System.Threading;
class Program
{
private static readonly ServiceController controller = new ServiceController("MSSQL$SQLEXPRESS");
private static readonly Stopwatch stopWatch = new Stopwatch();
static void Main(string[] args)
{
stopWatch.Start();
EnsureStop();
Start();
OpenAndClose("master");
EnsureStop();
Start();
OpenAndClose("AdventureWorksLT");
Console.ReadLine();
}
private static void EnsureStop()
{
Console.WriteLine("EnsureStop enter, {0:N0}", stopWatch.ElapsedMilliseconds);
if (controller.Status != ServiceControllerStatus.Stopped)
{
controller.Stop();
controller.WaitForStatus(ServiceControllerStatus.Stopped);
Thread.Sleep(5000); // really, really make sure it stopped ... this has a problem too.
}
Console.WriteLine("EnsureStop exit, {0:N0}", stopWatch.ElapsedMilliseconds);
}
private static void Start()
{
Console.WriteLine("Start enter, {0:N0}", stopWatch.ElapsedMilliseconds);
controller.Start();
controller.WaitForStatus(ServiceControllerStatus.Running);
// Thread.Sleep(5000);
Console.WriteLine("Start exit, {0:N0}", stopWatch.ElapsedMilliseconds);
}
private static void OpenAndClose(string database)
{
Console.WriteLine("OpenAndClose enter, {0:N0}", stopWatch.ElapsedMilliseconds);
var connection = new SqlConnection(string.Format(#"Data Source=.\SQLEXPRESS;initial catalog={0};integrated security=SSPI", database));
connection.Open();
connection.Close();
Console.WriteLine("OpenAndClose exit, {0:N0}", stopWatch.ElapsedMilliseconds);
}
}
}
On my machine, this will consistently fail as written. Notice that the connection to "master" has no problems; only the connection to the other database. (You can reverse the order of the connections to verify this.) If you uncomment the Thread.Sleep in the Start() method, it will work fine.
Obviously I want to avoid an arbitrary Thread.Sleep(). Besides the rank code smell, what arbitary value would I put there? The only thing we can think of is to put some dummy connections to our target database in a while loop, catching the SqlException thrown and trying again until it works. But I'm thinking there must be a more elegant solution out there to know when the service is really ready to be used. Any ideas?
EDIT: Based on feedback provided below, I added a check on the status of the database. However, it is still failing. It looks like even the state is not reliable. Here is the function I am calling before OpenAndClose(string):
private static void WaitForOnline(string database)
{
Console.WriteLine("WaitForOnline start, {0:N0}", stopWatch.ElapsedMilliseconds);
using (var connection = new SqlConnection(string.Format(#"Data Source=.\SQLEXPRESS;initial catal
using (var command = connection.CreateCommand())
{
connection.Open();
try
{
command.CommandText = "SELECT [state] FROM sys.databases WHERE [name] = #DatabaseName";
command.Parameters.AddWithValue("#DatabaseName", database);
byte databaseState = (byte)command.ExecuteScalar();
Console.WriteLine("databaseState = {0}", databaseState);
while (databaseState != OnlineState)
{
Thread.Sleep(500);
databaseState = (byte)command.ExecuteScalar();
Console.WriteLine("databaseState = {0}", databaseState);
}
}
finally
{
connection.Close();
}
}
Console.WriteLine("WaitForOnline exit, {0:N0}", stopWatch.ElapsedMilliseconds);
}
I found another discussion dealing with a similar problem. Apparently the solution is to check the sys.database_files of the database in question. But that, of course, is a chicken-and-egg problem. Any other ideas?
Service start != database start.
Service is started when the SQL Server process is running and responded to the SCM that is 'alive'. After that the server will start putting user databases online. As part of this process, it runs the recovery process on each database, to ensure transactional consistency. Recovery of a database can last anywhere from microseconds to whole days, it depends on the ammount of log to be redone and the speed of the disk(s).
After the SCM returns that the service is running, you should connect to 'master' and check your database status in sys.databases. Only when the status is ONLINE can you proceed to open it.