EF6 Retrying procedure throws "The SqlParameter is already contained by another SqlParameterCollection" for SqlQuery command

Question

EF6 Retrying procedure throws "The SqlParameter is already contained by another SqlParameterCollection" for SqlQuery command

ado.net c# entity-framework entity-framework-6 sql-server

Question

I'm trying to use the DBExecutionStrategy to retry queries that have timed out, but when the time out happens I get the error "The SqlParameter is already contained by another SqlParameterCollection". I'm using EF6.

My Query:

using (var ctx = new EntityModel())
{
    IEnumerable<ItemResponse> items= ctx.Database.SqlQuery<ItemResponse>(
           "spItemListGet @UserID", new SqlParameter("@UserID", UserID)
    ).ToList();
}

My Execution Strategy:

protected override bool ShouldRetryOn(Exception ex)
{
    bool retry = false;

    SqlException sqlException = ex as SqlException;
    if (sqlException != null)
    {
        int[] errorsToRetry =
        {
            -2,     //Timeout
        };
        if (sqlException.Errors.Cast<SqlError>().Any(x => errorsToRetry.Contains(x.Number)))
        {
            retry = true;
        }
        else
        {
            throw ex; //dont retry
        }
    }

    return retry;
}

The stack trace:

System.ArgumentException: The SqlParameter is already contained by another SqlParameterCollection.
   at System.Data.SqlClient.SqlParameterCollection.Validate(Int32 index, Object value)
   at System.Data.SqlClient.SqlParameterCollection.AddRange(Array values)
   at System.Data.Entity.Core.Objects.ObjectContext.CreateStoreCommand(String commandText, Object[] parameters)
   at System.Data.Entity.Core.Objects.ObjectContext.ExecuteStoreQueryInternal[TElement](String commandText, String entitySetName, ExecutionOptions executionOptions, Object[] parameters)
   at System.Data.Entity.Core.Objects.ObjectContext.<>c__DisplayClass65`1.<ExecuteStoreQueryReliably>b__64()
   at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
   at System.Data.Entity.Core.Objects.ObjectContext.<>c__DisplayClass65`1.<ExecuteStoreQueryReliably>b__63()
   at System.Data.Entity.Infrastructure.DbExecutionStrategy.Execute[TResult](Func`1 operation)
   at System.Data.Entity.Core.Objects.ObjectContext.ExecuteStoreQueryReliably[TElement](String commandText, String entitySetName, ExecutionOptions executionOptions, Object[] parameters)
   at System.Data.Entity.Core.Objects.ObjectContext.ExecuteStoreQuery[TElement](String commandText, ExecutionOptions executionOptions, Object[] parameters)
   at System.Data.Entity.Internal.InternalContext.<>c__DisplayClass14`1.<ExecuteSqlQuery>b__13()
   at System.Data.Entity.Internal.LazyEnumerator`1.MoveNext()
   at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)

What could it be done to prevent this error? Can Database.SqlQuery be used for with the execution strategy?

Bruno Pessanha

View more on Stack Overflow

Tamas · Accepted Answer · 11/11/2015 10:02:50 PM

The short answer: No, you can't do this (if your command has parameters).

The long answer: Here is a minimal repro of the issue. I stripped out the execution strategy from the picture, and faked it with a loop instead. This logic is implemented in the ObjectContext, specifically in the ExecuteStoreQueryInternalAsync method. The problem seems to be that a command.Parameters.Clear() call is missing from the cleanup part.

static void Main(string[] args)
{
    TestQuery();
}

private static void TestQuery()
{
    using (var ctx = new ProductContext())
    {
        var parameter = new SqlParameter("@ID", 1);
        var commandText = "select * from product where ProductId = @ID";

        Action a = () =>
        {
            IDbCommand command = new SqlCommand();
            command.CommandText = commandText;
            command.Parameters.Add(parameter);

            command.Connection = ctx.Database.Connection;
            if (command.Connection.State != ConnectionState.Open)
            {
                command.Connection.Open();
            }

            var reader = command.ExecuteReader();
            try
            {
                throw new Exception();
                while (reader.Read())
                {
                    var pId = reader["ProductID"];
                }
                reader.Close();
            }
            catch (Exception exc)
            {
                //for simplification, we just swallow this error, but in reality the connection error
                //would reach the IDbExecutionStrategy, and would do a retry. Instead we fake the retry
                //with a loop below
            }
            finally
            {
                reader.Dispose();

                //command.Parameters.Clear();  <--------- THIS LINE IS MISSING FROM EF
                command.Dispose();
            }
        };

        for (int i = 0; i < 2; i++) // we fake the retry with a loop now
        {
            a();
        }
    }
}

EF6 Retrying procedure throws "The SqlParameter is already contained by another SqlParameterCollection" for SqlQuery command

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