why I got this error Sequence contains no elements?

Question

I am using the following code in the view and tried a lot of solutions but still get this error
Sequence Contains no elements , this is the view code :

    @model AljawdahNewSite.Models.Orders_Tables  
    @{  
        ViewBag.Title = "Result Details";  
        //Layout = "~/Views/Shared/_LayoutPatients.cshtml";  
        var hema = new List<int>() { 1 };  
        var bio = new List<int>() { 2 };  
        var ser = new List<int>() { 3 };  
        var hor = new List<int>() { 4 };  
        var histo = new List<int>() { 5 };  
        var culture = new List<int>() { 8 };  
        var para = new List<int>() { 6 };  
        var covid = new List<int>() { 9 };  
      
        var labPara = Model.LabParaResult.FirstOrDefault();  
        var labCult = Model.LabCultureResults.FirstOrDefault();  
        var labMicro = Model.LabMicroResults.FirstOrDefault();  
        var labHisto = Model.LabHistoResult.FirstOrDefault();  
        var LabResults = Model.LabResults;  
        var labhema = LabResults.FirstOrDefault(x => x.deptid == 1);  
        var labBio = LabResults.FirstOrDefault(x => x.deptid == 2);  
        var labSer = LabResults.FirstOrDefault(x => x.deptid == 3);  
        var labHor = LabResults.FirstOrDefault(x => x.deptid == 4);  
        var labcovid = LabResults.FirstOrDefault(x => x.deptid == 9);  
      
        var LABCLINICVIEW = Model.labClinicsViewResult;  
        var LABCASHVIEW = Model.labCashView;  
        var labPara1 = Model.LabParasitologyView.FirstOrDefault();  
        var labCult1 = Model.LabCulturesView.FirstOrDefault();  
        var labMicro1 = Model.LabMicroView.FirstOrDefault();  
        var labHisto1 = Model.LabHistopathologyView.FirstOrDefault();  
        var labhema1 = LABCLINICVIEW.FirstOrDefault(x => x.DEPTID == 1);  
        var labBio1 = LABCLINICVIEW.FirstOrDefault(x => x.DEPTID == 2);  
        var labSer1 = LABCLINICVIEW.FirstOrDefault(x => x.DEPTID == 3);  
        var labHor1 = LABCLINICVIEW.FirstOrDefault(x => x.DEPTID == 4);  
        var labcovid1 = LABCLINICVIEW.FirstOrDefault(x => x.DEPTID == 9);  
    }   

this is part of controller code :

public ActionResult MasterDetails(int id)  
        {  
  
                
            var tables = new Orders_Tables  
            {  
                testsRanges = db.TestsRanges.ToList(),  
  
                LabResults = db.LAB_RESULTS.Where(o => o.ORDER_ID == id)  
                             .Include(p => p.LabTests)  
                             .Include(t => t.Patients).ToList(),  
  
  
                LabParaResult = db.LAB_PARA_RESULTS.Where(o => o.ORDER_ID == id).Include(t => t.Patients).Include(t => t.LabTests).Include(c => c.Customers).ToList(),  
                LabCultureResults = db.LAB_CULTURE_RESULT.Where(o => o.ORDER_ID == id).Include(t => t.Patients).Include(t => t.LabTests).Include(c => c.Customers).ToList(),  
                LabMicroResults = db.LAB_MICRO_NEGATIVE_RESULT.Where(o => o.ORDER_ID == id).ToList(),  
                labCashView = db.LAB_RESULT_CASH_VIEW.Where(o => o.order_number == id).ToList(),  
                labClinicsViewResult = db.LAB_RESULTS_CLINIC_VIEW.Where(o => o.order_number == id).ToList(),  
                LabParasitologyView = db.LAB_PARASITOLOGY_VIEW.Where(o => o.order_number == id).ToList(),  
                  
            };  
  
            return View(tables);  
             
        }  

the error show when try to run the result for

var labPara1 = Model.LabParasitologyView.FirstOrDefault();   

but the error appear in this line

var labcovid1 = LABCLINICVIEW.FirstOrDefault(x => x.DEPTID == 9);  

I need your help please :

How I will handle the controller code

If labClinicsViewResult is empty and returned no value skip and go to the next

Answer 1

Hi @ziad abuqasem ,
The reason for the error is: you want to fetch data from a null.
Maybe you can use DefaultIfEmpty(), if the given collection for calling DefaultIfEmpty() is empty, then the DefaultIfEmpty() method returns a new collection with a default value.

labClinicsViewResult = db.LAB_RESULTS_CLINIC_VIEW.Where(o => o.order_number == id).DefaultIfEmpty().ToList();  

Best regards,
Lan Huang

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