Populate Department class which contains a list of 'Employees' where there is no key from another entity class

You mean something like this:

using System;
using System.Collections.Generic;
using System.Linq;


namespace EE_Q29187042
{
    class Program
    {
        static void Main(string[] args)
        {
            var data = new[]
            {
                new DepartmentEmployee {DeptID = "1", EmpName = "A", DOJ = new DateTime(2020, 12, 20)},
                new DepartmentEmployee {DeptID = "1", EmpName = "B", DOJ = new DateTime(2020, 12, 20)},
                new DepartmentEmployee {DeptID = "2", EmpName = "C", DOJ = new DateTime(2020, 12, 20)},
                new DepartmentEmployee {DeptID = "2", EmpName = "D", DOJ = new DateTime(2020, 12, 20)}
            };


            var id = default(int);
            var departements = (from de in data
                                where int.TryParse(de.DeptID, out id)
                                group de by id into depts
                                select new Department { DeptID = depts.Key, DetailData = depts.Select(x => new Employee { EmpName = x.EmpName, DOJ = x.DOJ }).ToList() });


            foreach (var department in departements)
            {
                Console.WriteLine($"Department ID: {department.DeptID}");
                foreach (var employee in department.DetailData)
                {
                    Console.WriteLine($"{{ Employee Name: {employee.EmpName}, DOJ: {employee.DOJ.Value:dd-MM-yyyy} }}");
                }
                Console.WriteLine();
            }


            Console.ReadLine();
        }
    }


    class Department
    {
        public int DeptID { get; set; }
        public List<Employee> DetailData { get; set; }
    }


    class Employee
    {
        public string EmpName { get; set; }
        public DateTime? DOJ { get; set; }
    }


    class DepartmentEmployee
    {
        public string DeptID { get; set; }
        public string EmpName { get; set; }
        public DateTime? DOJ { get; set; }
    }
}

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Which produces the following output -
-saige-

Thank you so much, it_saige .

But I am getting one error on line

where int.TryParse(de.DeptID, out id) 

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it says that 'Argument 1: cannot convert from 'int' to 'string'.

Hi It_saige, I got another error message with the above-said code while using the for each loop, it says:

This function can only be invoked from LINQ to Entities.

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Appreciate your help....

The first issue is because the class that you originally defined is using an int instead.  Simple change:

using System;
using System.Collections.Generic;
using System.Linq;


namespace EE_Q29187042
{
    class Program
    {
        static void Main(string[] args)
        {
            var data = new[]
            {
                new DepartmentEmployee {DeptID = 1, EmpName = "A", DOJ = new DateTime(2020, 12, 20)},
                new DepartmentEmployee {DeptID = 1, EmpName = "B", DOJ = new DateTime(2020, 12, 20)},
                new DepartmentEmployee {DeptID = 2, EmpName = "C", DOJ = new DateTime(2020, 12, 20)},
                new DepartmentEmployee {DeptID = 2, EmpName = "D", DOJ = new DateTime(2020, 12, 20)}
            };


            var departements = (from de in data
                                group de by de.DeptID into depts
                                select new Department { DeptID = depts.Key, DetailData = depts.Select(x => new Employee { EmpName = x.EmpName, DOJ = x.DOJ }).ToList() });


            foreach (var department in departements)
            {
                Console.WriteLine($"Department ID: {department.DeptID}");
                foreach (var employee in department.DetailData)
                {
                    Console.WriteLine($"{{ Employee Name: {employee.EmpName}, DOJ: {employee.DOJ.Value:dd-MM-yyyy} }}");
                }
                Console.WriteLine();
            }


            Console.ReadLine();
        }
    }


    class Department
    {
        public int DeptID { get; set; }
        public List<Employee> DetailData { get; set; }
    }


    class Employee
    {
        public string EmpName { get; set; }
        public DateTime? DOJ { get; set; }
    }


    class DepartmentEmployee
    {
        public int DeptID { get; set; }
        public string EmpName { get; set; }
        public DateTime? DOJ { get; set; }
    }
}

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As for your second error.  Are you dealing with Entities here or classes like the ones you have defined?

-saige-

I am having classes as I defined here but with many columns that includes varoud datatypes like (int, varchchar, bit etc..)

Try creating a new console project and use just the code I posted.  Tell me if you get the same error.

-saige-

H it_seige,

I tried your code in the console it worked absolutely fine. whereas in  my case in the below line

var result = getDataFromStoreProcedure();//get data from sp

var Id = default(int);
var Department = (from de in result
              where int.TryParse(de.VehicleId, out Id)//Here I gets error message
              group de by Id into dept
              select new Department { VehicleId = dept.Key, DetailData = dept.Select(x => new Employee { NumTrips = x.NumTrips, HomeCount = x.HomeCount }).ToList() }); 

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After further amazing your code I found that you have used array whereas in my case I am filling my result variable via store procedure and then try to loop over to fill my entity classes, Dept & employee.

I get an error stating 'Argument 1: cannot convert from int to string'.

Appreciate your help.

Try this instead:

var result = getDataFromStoreProcedure();//get data from sp


var Department = (from de in result
                  group de by de.VehicleId into dept
                  select new Department { VehicleId = dept.Key, DetailData = dept.Select(x => new Employee { NumTrips = x.NumTrips, HomeCount = x.HomeCount }).ToList() });

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-saige-

Thank you, it_saige.

Appreciate your inputs...

Thanks, it_seige,  you nailed i :-)

Your following suggested solution worked for me, just having the last issue within that, here in this we have only one column from the department class i.e. DeptID, what if I have more columns than how could I accommodate them too here?

var departements = (from de in data
                                group de by de.DeptID into depts
                                select new Department { DeptID = depts.Key, DetailData = depts.Select(x => new Employee { EmpName = x.EmpName, DOJ = x.DOJ }).ToList() });




class Department
    {
        public int DeptID { get; set; }
       public string Description { get; set; }
       public DateTime DeptDate { get; set; }
        public Bit IsExist{ get; set; }
        public List<Employee> DetailData { get; set; }    }

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This is what I am trying but not working for me :-(

var departements = (from de in data group de by de.DeptID into depts                           select new Department { DeptID = depts.Key, 
                                 /*This is not working for me*/
                                 DeptID = depts.Key, 
                                 Description = depts.Description,
                                 DeptDate = depts.DeptDate,
                                 IsExist = depts.IsExist
         DetailData = depts.Select(x => new Employee { EmpName = x.EmpName, DOJ = x.DOJ }).ToList() });

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Thank You, Saige. It is working perfectly fine. Just want to know, can I loop through Department class as it is already filled by your code instead looping through var departments...?

 foreach (var department in departements)            
{
   Console.WriteLine($"{{ Department ID: {department.DeptID}, 
                           Description: {department.Description}, 
                           Date: {department.DeptDate}, 
                           IsExist: {department.IsExist} }}");                 
      foreach (var employee in department.DetailData)                 {                           Console.WriteLine($"{{ Employee Name: {employee.EmpName}, DOJ:          {employee.DOJ.Value:dd-MM-yyyy} }}");                 }                          Console.WriteLine(); 
}

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You must understand that DepartmentEmployees is a combination of Departments and Employees.  As such, simply looping through Departments will not suffice.  According to the requirements supplied, a List of Employees depends upon, at least, their department id.  So grouping by the data supplied by DepartmentEmployees provides the combination of both Departments and Employees per Department.

-saige-

Hi it_saige,

I just noticed that code is not returning all the data, if you see in the screenshot it is returning 03 rows whereas List contains 04 rows, i used above mentioned code...

var data = new[] { new DepartmentEmployee {DeptID = 1, Description = "Department 1", DeptDate = new DateTime(2000, 1, 1), IsExist = true, EmpName = "A", DOJ = new DateTime(2020, 12, 20)},
new DepartmentEmployee {DeptID = 1, Description = "Department 1", DeptDate = new DateTime(2000, 1, 1), IsExist = true, EmpName = "B", DOJ = new DateTime(2020, 12, 20)},  
new DepartmentEmployee {DeptID = 2, Description = "Department 2 (Old)", DeptDate = new DateTime(2000, 1, 1), IsExist = false, EmpName = "C", DOJ = new DateTime(2020, 12, 20)},  
new DepartmentEmployee {DeptID = 2, Description = "Department 2 (New)", DeptDate = new DateTime(2000, 2, 1), IsExist = true, EmpName = "D", DOJ = new DateTime(2020, 12, 20)} };
Which now produces the following output -

 

Please ignore above one, I mistakenly read something wrong... .code is fine... thank you