using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public record ApprovalLetter(int ApplyNowLoanPurposeId, bool IsHtml, string? Template);

    public record CobApprovalLetter(int ApplyNowLoanPurposeId, bool IsHtml, string? Template) : ApprovalLetter(ApplyNowLoanPurposeId, IsHtml, Template);

    public record CobPartnerApprovalLetterOverride(int PartnerId, int ApplyNowLoanPurposeId, bool IsHtml, string? Template) : ApprovalLetter(ApplyNowLoanPurposeId, IsHtml, Template);

    public static void Main()

    {

        var partnerId = 100;

        var cobApprovalLetter = new List<CobApprovalLetter>

        {

            new CobApprovalLetter(ApplyNowLoanPurposeId: 1, IsHtml: true, Template: "Templatel"),

            new CobApprovalLetter(ApplyNowLoanPurposeId: 2, IsHtml: false, Template: "Template2"),

            new CobApprovalLetter(ApplyNowLoanPurposeId: 3, IsHtml: true, Template: "Template3")

        };

        var cobPartnerApprovalLetterOverride = new List<CobPartnerApprovalLetterOverride>

        {

            new CobPartnerApprovalLetterOverride(ApplyNowLoanPurposeId: 1, PartnerId: partnerId, IsHtml: false, Template: "OverrideTemplate1"),

            new CobPartnerApprovalLetterOverride(ApplyNowLoanPurposeId: 3, PartnerId: partnerId, IsHtml: true, Template: null)

        };

​

        var queryResult =

            from approvalLetter in cobApprovalLetter

            join partnerOverride in cobPartnerApprovalLetterOverride on approvalLetter.ApplyNowLoanPurposeId equals partnerOverride.ApplyNowLoanPurposeId

            where partnerOverride.PartnerId == partnerId

            select new ApprovalLetter

            (

                ApplyNowLoanPurposeId: approvalLetter.ApplyNowLoanPurposeId,

                IsHtml: partnerOverride != null ? partnerOverride.IsHtml : approvalLetter.IsHtml,

                Template: partnerOverride == null ? null : partnerOverride.Template == null ? approvalLetter.Template : partnerOverride.Template

            );

​

        foreach (var item in queryResult)

            Console.WriteLine($"ApplyNowLoanPurposeId: {item.ApplyNowLoanPurposeId}, IsHtml: {item.IsHtml}, Template: {item. Template}");

        var HasApprovalLetter = queryResult.Any(x => x.ApplyNowLoanPurposeId == 3 && !x.IsHtml);

        Console.WriteLine($"HasApprovalLetter: {HasApprovalLetter}");

    }

}

​