Security Claims in DBCommandInterceptor - entity-framework

Question

i am currently using EF and .NET Core 3 through Radzen to build an application. This is working fine, but I want to add additional logging to the database. In order to do so, I would like to make use of the DBCommandInterceptor as shown here to do some post query commands.
Is it possible to get the Claims of the Microsoft Authorization in this Interceptor class? In my normal controller class, I can simply call
var userId = User.FindFirst(ClaimTypes.Name).Value;
This doesn't work in the Interceptor and to be honest, my knowledge about that framework is very poor. I cannot even tell you why I can access the User reference in my ObjectController against the DBCommandInterceptor

Answer 1

If you add the Interceptor in DbContext.OnConfiguring, you can pass any state to it you want.
So require your DbContext to accept an Identity, or with a service dependency it can use to access the user. something like:
public class Db : DbContext
{
ClaimsIdentity user;
public Db(ClaimsIdentity user)
{
this.user = user;
}
Then configure the Interceptor to accept the User, or the DbContext instance. eg
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseSqlServer("Server=localhost;Database=EFCore3Test;Integrated Security = true", a => a.UseRelationalNulls(true))
.ConfigureWarnings(c => c.Log((RelationalEventId.CommandExecuting, LogLevel.Information)))
.UseLoggerFactory(MyLoggerFactory)
.AddInterceptors(new MyCommandInterceptor(this));
base.OnConfiguring(optionsBuilder);
}
And have the interceptor use the constructor argument:
public class MyCommandInterceptor : DbCommandInterceptor
{
private Db db;
public MyCommandInterceptor(Db db)
{
this.db = db;
}
public override InterceptionResult<DbDataReader> ReaderExecuting(DbCommand command, CommandEventData eventData, InterceptionResult<DbDataReader> result)
{
var userId = db.user.FindFirst(ClaimTypes.Name).Value;
//. . .
return base.ReaderExecuting(command, eventData, result);
}
}