EF query to Oracle throwing "ORA-12704: character set mismatch"

Question

I'm trying to combine a few columns in EF from Oracle then do a .Contains() over the columns like this:

public IEnumerable<User> SearchUsers(string search)
{
    search = search.ToLower();

    return _securityUow.Users
            .Where(u => (u.FirstName.ToLower() + " " + u.LastName.ToLower() + " (" + u.NetId.ToLower() + ")").Contains(search))
            .OrderBy(u => u.LastName)
            .ThenBy(u => u.FirstName)
            .AsEnumerable();
}

However, I'm getting this exception:

{
  "Message": "An error has occurred.",
  "ExceptionMessage": "An error occurred while executing the command definition. See the inner exception for details.",
  "ExceptionType": "System.Data.Entity.Core.EntityCommandExecutionException",
  "StackTrace": "   at SoftwareRegistration.WebUI.Controllers.Api.V1.UserContactController.Lookup(String search) in C:\LocalRepository\OnlineSupport\SoftwareRegistration\trunk\release\SoftwareRegistration\SoftwareRegistration.WebUI\Controllers\Api\V1\UserContactController.cs:line 40\r\n   at lambda_method(Closure , Object , Object[] )\r\n   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass10.<GetExecutor>b__9(Object instance, Object[] methodParameters)\r\n   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.Execute(Object instance, Object[] arguments)\r\n   at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ExecuteAsync(HttpControllerContext controllerContext, IDictionary`2 arguments, CancellationToken cancellationToken)\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()\r\n   at System.Web.Http.Controllers.ApiControllerActionInvoker.<InvokeActionAsyncCore>d__0.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()\r\n   at System.Web.Http.Controllers.ActionFilterResult.<ExecuteAsync>d__2.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\r\n   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()\r\n   at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()",
  "InnerException": {
    "Message": "An error has occurred.",
    "ExceptionMessage": "ORA-12704: character set mismatch",
    "ExceptionType": "Oracle.ManagedDataAccess.Client.OracleException",
    "StackTrace": "   at OracleInternal.ServiceObjects.OracleCommandImpl.VerifyExecution(OracleConnectionImpl connectionImpl, Int32& cursorId, Boolean bThrowArrayBindRelatedErrors, OracleException& exceptionForArrayBindDML, Boolean& hasMoreRowsInDB, Boolean bFirstIterationDone)\r\n   at OracleInternal.ServiceObjects.OracleCommandImpl.ExecuteReader(String commandText, OracleParameterCollection paramColl, CommandType commandType, OracleConnectionImpl connectionImpl, OracleDataReaderImpl& rdrImpl, Int32 longFetchSize, Int64 clientInitialLOBFS, OracleDependencyImpl orclDependencyImpl, Int64[] scnForExecution, Int64[]& scnFromExecution, OracleParameterCollection& bindByPositionParamColl, Boolean& bBindParamPresent, Int64& internalInitialLOBFS, OracleException& exceptionForArrayBindDML, Boolean isDescribeOnly, Boolean isFromEF)\r\n   at Oracle.ManagedDataAccess.Client.OracleCommand.ExecuteReader(Boolean requery, Boolean fillRequest, CommandBehavior behavior)\r\n   at Oracle.ManagedDataAccess.Client.OracleCommand.ExecuteDbDataReader(CommandBehavior behavior)\r\n   at System.Data.Common.DbCommand.ExecuteReader(CommandBehavior behavior)\r\n   at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.<Reader>b__c(DbCommand t, DbCommandInterceptionContext`1 c)\r\n   at System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispatch[TTarget,TInterceptionContext,TResult](TTarget target, Func`3 operation, TInterceptionContext interceptionContext, Action`3 executing, Action`3 executed)\r\n   at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.Reader(DbCommand command, DbCommandInterceptionContext interceptionContext)\r\n   at System.Data.Entity.Internal.InterceptableDbCommand.ExecuteDbDataReader(CommandBehavior behavior)\r\n   at System.Data.Common.DbCommand.ExecuteReader(CommandBehavior behavior)\r\n   at System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition.ExecuteStoreCommands(EntityCommand entityCommand, CommandBehavior behavior)"
  }
}

The columns I'm querying are all of type VARCHAR2(128) in Oracle.

I'm also using this exact same code in another project and it works. The only difference is that for the project that works I'm using Oracle.DataAccess and for the one that doesn't work, I'm using Oracle.ManagedDataAccess (I am unable to use Oracle.DataAccess for this project). So I believe there is a bug/problem in the managed driver.

I'm open to solutions or workarounds.

Answer 1

In these cases, it is better to do the concatenation of these queries manually depending on whether the columns are unicode or not, in some of these ways

return _securityUow.Users
    .Where(u => (u.FirstName.ToLower() + DbFunctions.AsNonUnicode(" ") + u.LastName.ToLower() + DbFunctions.AsNonUnicode(" (") + u.NetId.ToLower() + DbFunctions.AsNonUnicode(")")).Contains(search))
    ...

return _securityUow.Users
    .Where(u => (u.FirstName.ToLower() + DbFunctions.AsUnicode(" ") + u.LastName.ToLower() + DbFunctions.AsUnicode(" (") + u.NetId.ToLower() + DbFunctions.AsUnicode(")")).Contains(search))
    ...

Depending on the type of columns if they are NVarchar or Varchar (by default EF uses nvarchar unless .isUnicode is set in the property)

Answer 2

I ended up getting the author of this (ODP.Net Managed Driver - ORA-12704: character set mismatch in generated code) to update the question, he posted a workaround using an interceptor, I'll go a bit more detail here...

First, I decorated my DBContext to load a configuration. you can skip this and just add to your configuration if you have one:

[DbConfigurationType(typeof(MyDbConfiguration))]
public partial class MyContext : DbContext

Create the config class:

public class MyDbConfiguration : DbConfiguration
{
    public MyDbConfiguration()
    {
        this.AddInterceptor(new NVarcharInterceptor()); //add this line to existing config.
    }
}

Next, create the interceptor:

public class NVarcharInterceptor : IDbCommandInterceptor
{
    public void NonQueryExecuted(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    {
        if (command != null && !string.IsNullOrWhiteSpace(command.CommandText))
            command.CommandText = command.CommandText.Replace("N''", "''");
    }

    public void NonQueryExecuting(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    {
        if (command != null && !string.IsNullOrWhiteSpace(command.CommandText))
            command.CommandText = command.CommandText.Replace("N''", "''");
    }

    public void ReaderExecuted(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
        if (command != null && !string.IsNullOrWhiteSpace(command.CommandText))
            command.CommandText = command.CommandText.Replace("N''", "''");
    }

    public void ReaderExecuting(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
        if (command != null && !string.IsNullOrWhiteSpace(command.CommandText))
            command.CommandText = command.CommandText.Replace("N''", "''");
    }

    public void ScalarExecuted(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    {
        if (command != null && !string.IsNullOrWhiteSpace(command.CommandText))
            command.CommandText = command.CommandText.Replace("N''", "''");
    }

    public void ScalarExecuting(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    {
        if (command != null && !string.IsNullOrWhiteSpace(command.CommandText))
            command.CommandText = command.CommandText.Replace("N''", "''");
    }
}