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LINQ, Lambda in Model Class

2019-09-08
MsJ
   

ASP.NET MVC에서는 기본적으로 생성된 프로젝트에서 모델(클래스)의 필드에 정의된 DisplayName을 View에서 표현할 수 있다. WPF/Winform에서 사용자 함수인 GetDisPlayName()을 사용해보고 여기에 LINQ, Lambda를 이용해서 모델을 사용하는 간단한 예제를 작성했다.

public static string GetDisPlayName<T>(string fieldName) where T : new()
{
    var nameInfo = typeof(T).GetProperty(fieldName);
    return nameInfo == null ? fieldName : nameInfo.GetCustomAttributes(typeof(DisplayNameAttribute), true).Cast<DisplayNameAttribute>().Single().DisplayName;
}

화면1

화면에서 사용한 전체 소소는 아래의 내용을 참고한다.

모델( class)
public class TEmployee
{
    [DisplayName("사원번호")]
    public int EmpNO { get; set; }

    [DisplayName("사원명")]
    public string EmpName { get; set; }

    [DisplayName("연봉")]
    public int Salary { get; set; }

    public TDepartment Department { get; set; }
}

public class TDepartment
{
    [DisplayName("부서번호")]
    public int DeptNO { get; set; }

    [DisplayName("부서명")]
    public string DeptName { get; set; }

    public virtual IEnumerable<TEmployee> Employee { get; set; }
}

public class TEmpDept
{
    public IList<TEmployee> Employee { get; set; }
    public IList<TDepartment> Department { get; set; }
}
전체소스
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
private static void Main()
{
    var emp = new List<TEmployee>
    {
        new TEmployee {EmpNO = 101, EmpName = "홍길동", Department = new TDepartment {DeptNO = 201}},
        new TEmployee {EmpNO = 102, EmpName = "홍길서", Department = new TDepartment {DeptNO = 202}},
        new TEmployee {EmpNO = 103, EmpName = "홍길남", Department = new TDepartment {DeptNO = 202}},
        new TEmployee {EmpNO = 104, EmpName = "홍길북", Department = new TDepartment {DeptNO = 203}}
    };

    var dept = new List<TDepartment>
    {
        new TDepartment {DeptNO = 201, DeptName = "부서1", Employee = emp.Where(x => x.Department.DeptNO == 201)},
        new TDepartment {DeptNO = 202, DeptName = "부서2", Employee = emp.Where(x => x.Department.DeptNO == 202)},
        new TDepartment {DeptNO = 203, DeptName = "부서3", Employee = emp.Where(x => x.Department.DeptNO == 203)}
    };

    foreach (var d in dept)
    {
        Console.WriteLine($"{d.DeptNO} {d.DeptName}");
        d.Employee.ToList().ForEach(e => Console.WriteLine($"    {e.EmpNO} {e.EmpName}"));
    }

    Console.WriteLine("---------------------------------------");

    foreach (var d in dept)
    {
        Console.WriteLine($"{d.DeptNO} {d.DeptName}");
        foreach (var e in emp.Where(e => e.Department.DeptNO == d.DeptNO))
        {
            Console.WriteLine($"    {e.EmpNO} {e.EmpName}");
        }
    }

    Console.WriteLine("---------------------------------------");

    /*
    var query =
        from d in dept
        join e in emp
            on d.DeptNO equals e.Department.DeptNO
        select new
        {
            d.DeptNO,
            d.DeptName,
            e.EmpNO,
            e.EmpName
        };
    */

    var query = dept.Join(emp, d => d.DeptNO, e => e.Department.DeptNO, (d, e) => new {d.DeptNO, d.DeptName, e.EmpNO, e.EmpName});

    foreach (var item in query)
    {
        Console.WriteLine($"{item.DeptNO}, {item.DeptName}, {item.EmpNO}, {item.EmpName}");
    }

    Console.WriteLine("-------------------------------------------------------");

    var empDept = new List<TEmpDept>
    {
        new TEmpDept {Department = dept, Employee = emp}
    };

    foreach (var item in empDept.Where(item => item != null))
    {
        item.Employee.ToList().ForEach(e =>
            Console.WriteLine($"{GetDisPlayName<TDepartment>("DeptNO")}:{e.Department.DeptNO}, " +
                              $"{GetDisPlayName<TDepartment>("DeptName")}:{item.Department.FirstOrDefault(d => d.DeptNO == e.Department.DeptNO).DeptName}, " +
                              $"{GetDisPlayName<TEmployee>("EmpNO")}:{e.EmpNO}, " +
                              $"{GetDisPlayName<TEmployee>("EmpName")}:{e.EmpName}")
        );
    }

    Console.WriteLine("-------------------------------------------------------");
}

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