InvalidOperationException: Sequence contains no elements. In Asp.net Core MVC with Entity framework

发布于 2020-04-11 11:37:59

I am getting this error one of my projects.

InvalidOperationException: Sequence contains no elements.

here is my code in this I am trying to create auto-generated Id with string format.

 public async Task<IActionResult> Create()
    {
        int id = _db.Patient.Max(item => item.Id)+1;

        ViewBag.autoid = "BL0000"+id.ToString(); 
        return View();
    }

Questioner

SK jha

Viewed

Chinese

Original

public async Task<IActionResult> Create() { //x = _db.Patient.Max(item => item.Id); x=_db.Patient.DefaultIfEmpty().Max(item => item == null ? 1 : item.Id+1); ViewBag.autoid = "BL0000"+x.ToString(); return View(); }

InvalidOperationException: Sequence contains no elements. In Asp.net Core MVC with Entity framework

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