At one point using FromSqlRaw to call stored procedures worked for me. I did not change anything in the project but now calling any stored procedure using FromSqlRaw returns
The underlying reader doesn't have as many fields as expected
I removed the model from the project and performed a BUILD. Then added the model back with no luck. I reduced the model and stored procedure to return a single column, no luck.
I tried adding Microsoft.EntityFrameworkCore.Relational as a dependency, no luck. All my unit test that use FromSqlRaw to call a stored procedure return the same error and at one time they all worked.
I have received Windows updates but nothing I know about that would have affected EF Core. I have run through all internet problem solving I can find. I am starting to think I will need to use ADO as a work around but I do not want a work around when it worked for me at one point. Something changed on my machine but I am not sure what to cause this problem.
Here is my test method in case my code is messed up. It is very straight forward not much to mess up. I tried the "var" out of desperation.
[TestMethod]
public void WorkOrderBOMGridABS()
{
List<WorkOrderBOMGridABS> baseList = new List<WorkOrderBOMGridABS>();
using (WorkOrderDataContext context = new WorkOrderDataContext())
{
var param = new SqlParameter[] {
new SqlParameter() {
ParameterName = "#WorkOrderId",
SqlDbType = System.Data.SqlDbType.Int,
Direction = System.Data.ParameterDirection.Input,
Value = 38385
}
};
baseList = context.WorkOrderBOMGridABS.FromSqlRaw("[dbo].[WorkOrderBOMGridABS] #WorkOrderId", param).ToList();
//var results = context.WorkOrderBOMGridABS.FromSqlRaw("[dbo].[WorkOrderBOMGridABS] #WorkOrderId", param).ToList();
Assert.IsNotNull(baseList);
}
}
I was using an old table to get the Unit Of Measure value that had an integer ID value. I switched it to use a new table with a VARCHAR ID value. Making this change to the stored proc and model code allowed the FromRawSql to work. Not sure why because while the integer ID value was getting an integer, either 0 or number other than 0, it was a valid value for the model. Any error message I received did not mention this UnitId field. It was a pain but I am glad it is resolved. At least until the next error I run into that much is guaranteed.
Using ASP.Net core 3.0. my Database query works - I can get the result set (records), but how to pass/get the output parameter? Also would like to know if there's a way to get the return value.
I tried using different ways to call the SQL query and the only one I was able to get working was FromSqlInterpolated, but open to different methods.
This code works for me, but I want to pass an additional parameter that can get populated as an output parameter (which is working when I test it by calling the stored proc from within SQL Server).
var result = _context.Users
.FromSqlInterpolated($"EXEC mystoredproc {user.Username} ").AsEnumerable().FirstOrDefault();
I tried creating a variable before the call
string out1 = null;
And then including that in the call but I can't figure out the syntax and I'm not sure if it's supported with this method.
var result = _context.Users
.FromSqlInterpolated($"EXEC mystoredproc {user.Username}, OUTPUT {out1}").AsEnumerable().FirstOrDefault();
Console.WriteLine(out1);
Hoping someone can point me in the right direction - would like to know both how to use the output parameter and how to get the return value, not just the record set. Thank you.
The answer accepted does not seem to work for me.
However I finally manage to have the OUTPUT parameter work by using the following code
var p0 = new SqlParameter("#userName", {user.Username});
var p1 = new SqlParameter("#out1", System.Data.SqlDbType.NVarChar, 20) { Direction = System.Data.ParameterDirection.Output };
string out1 = null;
var result = _context.Users
.FromSqlRaw($"EXEC mystoredproc #userName, #out1 OUTPUT ", p0, p1).AsEnumerable().FirstOrDefault();
Console.WriteLine(p1.Value); // Contains the new value of the p1 parameter
Just a litte warning, the p1 value property will be changed only when the request will be executed (by an AsEnumerable, Load() or anything that forces the Sql execution)
I have a form with customer info that needs to be processed one transaction per page. I'm using the binding navigator to manage my pagination.
It works in all but some cases. In the cases where it doesn't work, I have to open a different window to look up information and return it to the main form. Here is the code for that:
// save current work
updateDataTable();
// Open a window and get new customer info
// CurrentCustomer is returned from the opened window
using (SqlConnection cx = new SqlConnection(GetConnectionString()))
{
DataRowView dataRow = (DataRowView)procBindingSource.Current;
dataRow.BeginEdit();
dataRow["CUSTOMER"] = CurrentCustomer;
dataRow.EndEdit();
updateDataItems();
SqlCommand cmd = new SqlCommand(
#" select acct_no from cust_processing where id = #id ", cx);
cmd.Parameters.AddWithValue("#id", (int)dataRow["ID"]);
cx.Open();
var results = cmd.ExecuteScalar();
if (results != null)
{
dataRow.BeginEdit();
dataRow["ACCT_NO"] = results.ToString();
dataRow.EndEdit();
updateDataItems(); <------ CONCURRENCY ERROR
}
}
The error I am getting is a concurrency error. I think that I have more than one version of the row possibly ? I thought I was making sure that I was on the most recent version of the row by calling updateDataTable(). I am the only user so I know I am creating the problem myself.
Here is my update method which is called when I change pages or save and exit or want to write the commit the data:
void updateDataItems()
{
this.procBindingSource.EndEdit();
this.procTableAdapter.Update(xyzDataSet);
xyzDataSet.AcceptChanges();
}
I have tried executing updateDataItems from various places such as after I assign dataRow["ACCT_NO"] = results.ToString() or before and after assigning that.
I'm pretty much down to guess and check so any thoughts, help and advice will be appreciated and +1.
Okay -- so the problem was that I was trying to update the current row from the program and also using the binding navigator. They were not working together properly.
The solution was to add a text box to the form in the forms designer and set visible = false and bind it to ACCT_NO. Once I got the results from my other form, I just needed to set the .text property of the ACCT_NO textbox to the new value and the binding navigator managed all my updates for me correctly.
txtAcct_No.text = results.ToString();
I have this query and I get the error in this function:
var accounts = from account in context.Accounts
from guranteer in account.Gurantors
select new AccountsReport
{
CreditRegistryId = account.CreditRegistryId,
AccountNumber = account.AccountNo,
DateOpened = account.DateOpened,
};
return accounts.AsEnumerable()
.Select((account, index) => new AccountsReport()
{
RecordNumber = FormattedRowNumber(account, index + 1),
CreditRegistryId = account.CreditRegistryId,
DateLastUpdated = DateLastUpdated(account.CreditRegistryId, account.AccountNumber),
AccountNumber = FormattedAccountNumber(account.AccountType, account.AccountNumber)
})
.OrderBy(c=>c.FormattedRecordNumber)
.ThenByDescending(c => c.StateChangeDate);
public DateTime DateLastUpdated(long creditorRegistryId, string accountNo)
{
return (from h in context.AccountHistory
where h.CreditorRegistryId == creditorRegistryId && h.AccountNo == accountNo
select h.LastUpdated).Max();
}
Error is:
There is already an open DataReader associated with this Command which must be closed first.
Update:
stack trace added:
InvalidOperationException: There is already an open DataReader associated with this Command which must be closed first.]
System.Data.SqlClient.SqlInternalConnectionTds.ValidateConnectionForExecute(SqlCommand command) +5008639
System.Data.SqlClient.SqlConnection.ValidateConnectionForExecute(String method, SqlCommand command) +23
System.Data.SqlClient.SqlCommand.ValidateCommand(String method, Boolean async) +144
System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) +87
System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) +32
System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method) +141
System.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior) +12
System.Data.Common.DbCommand.ExecuteReader(CommandBehavior behavior) +10
System.Data.EntityClient.EntityCommandDefinition.ExecuteStoreCommands(EntityCommand entityCommand, CommandBehavior behavior) +443
[EntityCommandExecutionException: An error occurred while executing the command definition. See the inner exception for details.]
System.Data.EntityClient.EntityCommandDefinition.ExecuteStoreCommands(EntityCommand entityCommand, CommandBehavior behavior) +479
System.Data.Objects.Internal.ObjectQueryExecutionPlan.Execute(ObjectContext context, ObjectParameterCollection parameterValues) +683
System.Data.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption) +119
System.Data.Objects.ObjectQuery`1.System.Collections.Generic.IEnumerable<T>.GetEnumerator() +38
System.Linq.Enumerable.Single(IEnumerable`1 source) +114
System.Data.Objects.ELinq.ObjectQueryProvider.<GetElementFunction>b__3(IEnumerable`1 sequence) +4
System.Data.Objects.ELinq.ObjectQueryProvider.ExecuteSingle(IEnumerable`1 query, Expression queryRoot) +29
System.Data.Objects.ELinq.ObjectQueryProvider.System.Linq.IQueryProvider.Execute(Expression expression) +91
System.Data.Entity.Internal.Linq.DbQueryProvider.Execute(Expression expression) +69
System.Linq.Queryable.Max(IQueryable`1 source) +216
CreditRegistry.Repositories.CreditRegistryRepository.DateLastUpdated(Int64 creditorRegistryId, String accountNo) in D:\Freelance Work\SuperExpert\CreditRegistry\CreditRegistry\Repositories\CreditRegistryRepository.cs:1497
CreditRegistry.Repositories.CreditRegistryRepository.<AccountDetails>b__88(AccountsReport account, Int32 index) in D:\Freelance Work\SuperExpert\CreditRegistry\CreditRegistry\Repositories\CreditRegistryRepository.cs:1250
System.Linq.<SelectIterator>d__7`2.MoveNext() +198
System.Linq.Buffer`1..ctor(IEnumerable`1 source) +217
System.Linq.<GetEnumerator>d__0.MoveNext() +96
This can happen if you execute a query while iterating over the results from another query. It is not clear from your example where this happens because the example is not complete.
One thing that can cause this is lazy loading triggered when iterating over the results of some query.
This can be easily solved by allowing MARS in your connection string. Add MultipleActiveResultSets=true to the provider part of your connection string (where Data Source, Initial Catalog, etc. are specified).
You can use the ToList() method before the return statement.
var accounts =
from account in context.Accounts
from guranteer in account.Gurantors
select new AccountsReport
{
CreditRegistryId = account.CreditRegistryId,
AccountNumber = account.AccountNo,
DateOpened = account.DateOpened,
};
return accounts.AsEnumerable()
.Select((account, index) => new AccountsReport()
{
RecordNumber = FormattedRowNumber(account, index + 1),
CreditRegistryId = account.CreditRegistryId,
DateLastUpdated = DateLastUpdated(account.CreditRegistryId, account.AccountNumber),
AccountNumber = FormattedAccountNumber(account.AccountType, account.AccountNumber)
})
.OrderBy(c=>c.FormattedRecordNumber)
.ThenByDescending(c => c.StateChangeDate)
.ToList();
public DateTime DateLastUpdated(long creditorRegistryId, string accountNo)
{
var dateReported = (from h in context.AccountHistory
where h.CreditorRegistryId == creditorRegistryId && h.AccountNo == accountNo
select h.LastUpdated).Max();
return dateReported;
}
Use the syntax .ToList() to convert object read from db to list to avoid being re-read again.
Here is a working connection string for someone who needs reference.
<connectionStrings>
<add name="IdentityConnection" connectionString="Data Source=(LocalDb)\v11.0;AttachDbFilename=|DataDirectory|\IdentityDb.mdf;Integrated Security=True;MultipleActiveResultSets=true;" providerName="System.Data.SqlClient" />
</connectionStrings>
In my case, using Include() solved this error and depending on the situation can be a lot more efficient then issuing multiple queries when it can all be queried at once with a join.
IEnumerable<User> users = db.Users.Include("Projects.Tasks.Messages");
foreach (User user in users)
{
Console.WriteLine(user.Name);
foreach (Project project in user.Projects)
{
Console.WriteLine("\t"+project.Name);
foreach (Task task in project.Tasks)
{
Console.WriteLine("\t\t" + task.Subject);
foreach (Message message in task.Messages)
{
Console.WriteLine("\t\t\t" + message.Text);
}
}
}
}
I dont know whether this is duplicate answer or not. If it is I am sorry. I just want to let the needy know how I solved my issue using ToList().
In my case I got same exception for below query.
int id = adjustmentContext.InformationRequestOrderLinks.Where(
item => item.OrderNumber == irOrderLinkVO.OrderNumber
&& item.InformationRequestId == irOrderLinkVO.InformationRequestId)
.Max(item => item.Id);
I solved like below
List<Entities.InformationRequestOrderLink> links =
adjustmentContext.InformationRequestOrderLinks
.Where(item => item.OrderNumber == irOrderLinkVO.OrderNumber
&& item.InformationRequestId == irOrderLinkVO.InformationRequestId)
.ToList();
int id = 0;
if (links.Any())
{
id = links.Max(x => x.Id);
}
if (id == 0)
{
//do something here
}
It appears that you're calling DateLastUpdated from within an active query using the same EF context and DateLastUpdate issues a command to the data store itself. Entity Framework only supports one active command per context at a time.
You can refactor your above two queries into one like this:
return accounts.AsEnumerable()
.Select((account, index) => new AccountsReport()
{
RecordNumber = FormattedRowNumber(account, index + 1),
CreditRegistryId = account.CreditRegistryId,
DateLastUpdated = (
from h in context.AccountHistory
where h.CreditorRegistryId == creditorRegistryId && h.AccountNo == accountNo
select h.LastUpdated
).Max(),
AccountNumber = FormattedAccountNumber(account.AccountType, account.AccountNumber)
})
.OrderBy(c=>c.FormattedRecordNumber)
.ThenByDescending(c => c.StateChangeDate);
I also noticed you're calling functions like FormattedAccountNumber and FormattedRecordNumber in the queries. Unless these are stored procs or functions you've imported from your database into the entity data model and mapped correct, these will also throw excepts as EF will not know how to translate those functions in to statements it can send to the data store.
Also note, calling AsEnumerable doesn't force the query to execute. Until the query execution is deferred until enumerated. You can force enumeration with ToList or ToArray if you so desire.
In my case, I had opened a query from data context, like
Dim stores = DataContext.Stores _
.Where(Function(d) filter.Contains(d.code)) _
... and then subsequently queried the same...
Dim stores = DataContext.Stores _
.Where(Function(d) filter.Contains(d.code)).ToList
Adding the .ToList to the first resolved my issue. I think it makes sense to wrap this in a property like:
Public ReadOnly Property Stores As List(Of Store)
Get
If _stores Is Nothing Then
_stores = DataContext.Stores _
.Where(Function(d) Filters.Contains(d.code)).ToList
End If
Return _stores
End Get
End Property
Where _stores is a private variable, and Filters is also a readonly property that reads from AppSettings.
As a side-note...this can also happen when there is a problem with (internal) data-mapping from SQL Objects.
For instance...
I created a SQL Scalar Function that accidentally returned a VARCHAR...and then...used it to generate a column in a VIEW. The VIEW was correctly mapped in the DbContext...so Linq was calling it just fine. However, the Entity expected DateTime? and the VIEW was returning String.
Which ODDLY throws...
"There is already an open DataReader associated with this Command
which must be closed first"
It was hard to figure out...but after I corrected the return parameters...all was well
In addition to Ladislav Mrnka's answer:
If you are publishing and overriding container on Settings tab, you can set MultipleActiveResultSet to True. You can find this option by clicking Advanced... and it's going to be under Advanced group.
I solved this problem by changing
await _accountSessionDataModel.SaveChangesAsync();
to
_accountSessionDataModel.SaveChanges();
in my Repository class.
public async Task<Session> CreateSession()
{
var session = new Session();
_accountSessionDataModel.Sessions.Add(session);
await _accountSessionDataModel.SaveChangesAsync();
}
Changed it to:
public Session CreateSession()
{
var session = new Session();
_accountSessionDataModel.Sessions.Add(session);
_accountSessionDataModel.SaveChanges();
}
The problem was that I updated the Sessions in the frontend after creating a session (in code), but because SaveChangesAsync happens asynchronously, fetching the sessions caused this error because apparently the SaveChangesAsync operation was not yet ready.
For those finding this via Google;
I was getting this error because, as suggested by the error, I failed to close a SqlDataReader prior to creating another on the same SqlCommand, mistakenly assuming that it would be garbage collected when leaving the method it was created in.
I solved the issue by calling sqlDataReader.Close(); before creating the second reader.
Most likely this issue happens because of "lazy loading" feature of Entity Framework. Usually, unless explicitly required during initial fetch, all joined data (anything that stored in other database tables) is fetched only when required. In many cases that is a good thing, since it prevents from fetching unnecessary data and thus improve query performance (no joins) and saves bandwidth.
In the situation described in the question, initial fetch is performed, and during "select" phase missing lazy loading data is requested, additional queries are issued and then EF is complaining about "open DataReader".
Workaround proposed in the accepted answer will allow execution of these queries, and indeed the whole request will succeed.
However, if you will examine requests sent to the database, you will notice multiple requests - additional request for each missing (lazy loaded) data. This might be a performance killer.
A better approach is to tell to EF to preload all needed lazy loaded data during the initial query. This can be done using "Include" statement:
using System.Data.Entity;
query = query.Include(a => a.LazyLoadedProperty);
This way, all needed joins will be performed and all needed data will be returned as a single query. The issue described in the question will be solved.
The same error happened to me when I was looping and updating data on
IEnumerable<MyClass>
When I changed the looped-on collection to be List<MyClass>, and filled it by converting by .ToList(), it solved and updated without any errors.
I had the same error, when I tried to update some records within read loop.
I've tried the most voted answer MultipleActiveResultSets=true and found, that it's just workaround to get the next error
New transaction is not allowed because there are other threads running
in the session
The best approach, that will work for huge ResultSets is to use chunks and open separate context for each chunk as described in
SqlException from Entity Framework - New transaction is not allowed because there are other threads running in the session
Well for me it was my own bug. I was trying to run an INSERT using SqlCommand.executeReader() when I should have been using SqlCommand.ExecuteNonQuery(). It was opened and never closed, causing the error. Watch out for this oversight.
This is extracted from a real world scenario:
Code works well in a Stage environment with MultipleActiveResultSets is set in the connection string
Code published to Production environment without MultipleActiveResultSets=true
So many pages/calls work while a single one is failing
Looking closer at the call, there is an unnecessary call made to the db and needs to be removed
Set MultipleActiveResultSets=true in Production and publish cleaned up code, everything works well and, efficiently
In conclusion, without forgetting about MultipleActiveResultSets, the code might have run for a long time before discovering a redundant db call that could be very costly, and I suggest not to fully depend on setting the MultipleActiveResultSets attribute but also find out why the code needs it where it failed.
I am using web service in my tool, where those service fetch the stored procedure. while more number of client tool fetches the web service, this problem arises. I have fixed by specifying the Synchronized attribute for those function fetches the stored procedure. now it is working fine, the error never showed up in my tool.
[MethodImpl(MethodImplOptions.Synchronized)]
public static List<t> MyDBFunction(string parameter1)
{
}
This attribute allows to process one request at a time. so this solves the Issue.
In my case, I had to set the MultipleActiveResultSets to True in the connection string.
Then it appeared another error (the real one) about not being able to run 2 (SQL) commands at the same time over the same data context! (EF Core, Code first)
So the solution for me was to look for any other asynchronous command execution and turn them to synchronous, as I had just one DbContext for both commands.
I hope it helps you