using System;

using System.Linq;

​

​

class School

{

    public Student[] Students{get;set;}

}

​

class Student 

{

    public string Name {get;set;}   

    public string FatherName {get;set;}

    public string Message{get;set;}

    public bool Invalid{get;set;}

​

}

​

public class Program

{

    public static void Validate(bool checkFixValues){       

    var jobCodeAndOrgUnitDefault = new School(){ Students = new [] { new Student(){ Name="Bob", FatherName="David"}, new Student(){ Name="Jack", FatherName="Sparrow"}, new Student(){ Name="s", FatherName="Khan"}} };

        var EmpValues = new School(){ Students = new [] { new Student(){ Name="Bob   ", FatherName="David"},new Student(){ Name="Bob", FatherName=""}, new Student(){ Name="Jack", FatherName=""}, new Student(){ Name="Jack", FatherName=""}} };

        var ss= EmpValues.Students.GroupJoin(jobCodeAndOrgUnitDefault.Students,

                                   ej => new {Name=ej.Name.Trim(), FName=ej.FatherName.Trim()},

                  jd =>new  {Name= jd.Name.Trim(), FName=jd.FatherName.Trim()},

                  (e,j) => new { EmpJobCode = e, JobCodeDef = j }) .SelectMany(

                  valid => valid.JobCodeDef.DefaultIfEmpty(),

                  (x,y) => new { EmpJobCode = x.EmpJobCode, JDef = y }) 

        .Select(s=>{

            if((checkFixValues ? s.EmpJobCode.Invalid : true)

                  &&s.JDef== null){

                s.EmpJobCode.Message= "Invalid" ;

                s.EmpJobCode.Invalid=true;}

            return s.EmpJobCode;});

        foreach(var student in ss){

            Console.WriteLine(student.Name+student.Message);

        }

    }

    public static void Main()

    {

        var schools = new [] {

            new School(){ Students = new [] { new Student(){ Name="Bob", FatherName="David"}, new Student(){ Name="Jack", FatherName="Sparrow"} }},

            new School(){ Students = new [] { new Student(){ Name="Bob", FatherName="David"}, new Student(){ Name="Jim", FatherName="Brown"}, new Student(){ Name="John", FatherName="David"} }}

        };

        var allStudents = schools.SelectMany(s=> s.Students);               

​

        Validate(false);

    }

}