how to prevent Entity-Framework to generate N'..' prefixed unicode strings? - entity-framework

Question

I use EF 4.1 Code-First ,
the problem is: EF generates all the unicode fields with N'..' prefix by default. like this :
exec sp_executesql
N'SELECT ...
FROM ...
WHERE [Title] LIKE #p__linq__0 ESCAPE N''~''',
N'#p__linq__0 nvarchar(4000)',
#p__linq__0=N'%...%'
but it cause me some problems in some characters. I want to know if there is a way to prevent EF of adding N prefix or not?

Answer 1

You can wrap your strings in AsNonUnicode method as mentioned at http://msdn.microsoft.com/en-us/library/system.data.objects.entityfunctions.asnonunicode.aspx this will generate normal strings.

Answer 2

Another solution would be to use CommandInterceptors and modify the resulting sql query before it gets executed.
I had similar problems with an oracle database and ODP.net provider.
AsNonUnicode didn't solved my problem.
EF 6 provides the ability to intercept the context using IDbCommandInterceptor before and after it performs the ExecuteNonQuery, ExecuteScalar, ExecuteReader operations to the database. You will need to configure the interceptor either by using config file or code-based configuration.
Config file:
<entityFramework>
<interceptors>
<interceptor type="EfSample.EfCommandInterceptor, EfSample">
</interceptor>
</interceptors>
</entityFramework>
Code-based config:
public sealed class EntityFrameworkConfiguration : DbConfiguration
{
public EntityFrameworkConfiguration ()
{
this.AddInterceptor(new EfCommandInterceptor());
}
}
Create the CommandInterceptor as shown below:
public sealed class EfCommandInterceptor
: DbCommandInterceptor
{
/// <summary>
/// Called when Reader is executing.
/// </summary>
/// <param name="command"></param>
/// <param name="interceptionContext"></param>
/// <inheritdoc />
public override void ReaderExecuting(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
{
if(command.CommandText.Contains("N''"))
{
command.CommandText = command.CommandText.Replace("N''", "''");
}
base.ReaderExecuting(command, interceptionContext);
}
}