The extension function for entity framework core.
public class Token{
public virtual Guid Id { get; set; }
}
[HttpPost]
public async Task<IActionResult> Post(Token token)
{
//token.Id=Guid.Empty
token = token.SupplyGuidKeyIfEmpty(_dbContext.Model);
// now token.Id is new guid.
_dbContext.Tokens.Add(token);
if (await _dbContext.SaveChangesAsync() > 0)
{
return Ok(token.Id);
}
return BadRequest();
}