How to use a SQL output parameter with FromSqlInterpolated? Or alternative - sql-server

Question

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.

Answer 1

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)