Layer cannot access the methods used in the layer it references

Question

I have 3 projects in the same solution, 3-tier architecture.

However I am failing to show my presentations in the presentation layer I get the error CS0103, my thought is that the layer cannot access the methods used in the layer it references. If that's the case then how can I reference these methods or suggest an easy way to do this?

My presentation layer references the following code

using Data_Link;
using static Data_Link.Program;
using Microsoft.VisualBasic.FileIO;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;


namespace Business_Logic
{
    public class Program 
    {


        List<Card> CrackableCards = GetCrackablePINS(AllCards);
        List<Card> ExpiredCards = GetExpiredCards(AllCards);
        List<Card> ExpiringCards = GetExpiringCards(AllCards);
        List<Card> HNWIs = GetHNWI(AllCards);

        public static List<Card> AllCards { get; private set; }

        /* List<Card> AllCards = new List<Card>();
         public int[] computeFrequency(List<LotteryEntry> historicalData)
         public static 

         */
        //Returns crackable pins
        private static List<Card> GetCrackablePINS(List<Card> cards)
        {
            List<Card> CrackableCards = GetCrackablePINS(AllCards);
            List<Card> results = new List<Card>();
            foreach (var card in cards)
            {
                if (IsCrackable(card.CardPIN))
                    results.Add(card);
            }
            return results;

        }
        //Returns expired cards
        private static List<Card> GetExpiredCards(List<Card> cards)
        {
            List<Card> results = new List<Card>();
            foreach (var card in cards)
            {
                if (HasExpired(card.ExpiryDate))
                    results.Add(card);
            }
            return results;
        }
        //Returns expiring cards
        private static List<Card> GetExpiringCards(List<Card> cards)
        {
            List<Card> results = new List<Card>();
            foreach (var card in cards)
            {
                if (IsExpiring(card.ExpiryDate))
                    results.Add(card);
            }
            return results;
        }
        //Returns HNWIs
        private static List<Card> GetHNWI(List<Card> cards)
        {
            List<Card> results = new List<Card>();
            foreach (var card in cards)
            {
                if (IsHNWI(card.CardLimit))
                    results.Add(card);
            }
            return results;
        }
        //Generates report in csv
         private void GenerateReport(List<Card> cardCriteria, string fileName)
        {
            string heading = "Card Type Code,Card Type Full Name,Issuing Bank,Card Number,Card Holder's Name,CVV/CVV2,Issue Date,Expiry Date,Billing Date,Card PIN,Credit Limit";
            File.WriteAllText(fileName, heading);
            foreach (var card in cardCriteria)
            {
                try
                {
                    string details = card.CardTypeCode + "," + card.CardTypeFullName + "," + card.IssusingBank + "," + card.CardNumber + "," + card.CardHolderName + "," + card.CVV + "," + card.IssueDate + "," + card.ExpiryDate + "," + card.BillingDate + "," + card.CardPIN + "," + card.CardLimit;
                    File.AppendAllText(fileName, details);
                }
                catch (Exception e)
                {
                    Console.WriteLine(e.Message);
                }
            }
        }
        //Checks if a card pin is crackable
        private static bool IsCrackable(string PIN)
        {
            if (PIN[0] == PIN[1] || PIN[1] == PIN[2] || PIN[2] == PIN[3])
            {
                return true;
            }
            else if ((int)PIN[0] == (int)PIN[1] - 1 && (int)PIN[1] == (int)PIN[2] - 1 && (int)PIN[2] == PIN[3] - 1)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
        //Checks if the card has expired
        private static bool HasExpired(string date)
        {
            string[] dateString = date.Split('/');
            int month = int.Parse(dateString[0]);
            int year = int.Parse(dateString[1]);
            if (month <= 2 && year <= 2020)
                return true;
            else
                return false;
        }
        //Checks if the card is expiring
        private static bool IsExpiring(string date)
        {
            string[] dateString = date.Split('/');
            int month = int.Parse(dateString[0]);
            int year = int.Parse(dateString[1]);
            if (month == DateTime.Now.Month && year == DateTime.Now.Year)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
        //Checks if a card is an HNWI
        private static bool IsHNWI(int HNWI)
        {
            const int limit = 149999;
            if (HNWI > limit)
                return true;
            else
                return false;
        }
    }
}

Pro tip: questions that have a title that is just general pleading will generally get closed here. Titles should always be indicative of a post's content. — halfer, Mar 21 '20 at 11:03
You are using static methods, but the fields are per instance. Either declare your fields as `static` or instantiate a new instance of Program like this in the Main : `var myProgramInstance = new Program();`, and use `myProgramInstance.CrackableCards` for lists , etc.. — Pac0, Mar 21 '20 at 11:04
as the Main method is static, it doesn't corresponds to an instance, so it doesn't "see" the lists you declared . But you can create an instance without issue. You need to get basic training on OOP (Object Oreinted Programmin) for the understanding. — Pac0, Mar 21 '20 at 11:07
Ah, I haven't noticed it's not the same namespace. See Jasper Kent answer. — Pac0, Mar 21 '20 at 11:08

score 1 · Answer 1 · answered Mar 21 '20 at 11:13

1

You're using static BusinessLogic.Program will allow public static member of BusinessLogic.Program to be accessed.

However, your fields (ExpiredCards etc) are non-static and private (by default). Precede each of this with public static.

That said, it would probably be more maintainable to avoid static data. Instead, create and instance of BusinessLogic.Program inside Main().

answered Mar 21 '20 at 11:13

Jasper Kent

3,546
15
21

Which main? in the data, business or presentation layer? – Lebea Tshwarelo Tevin Kdot Mar 21 '20 at 11:36
You should only have one Main. Your business layer is (presumably) a DLL, so will not have a Main. Your presentation layer is (presumably) an EXE and has a Main. A DLL cannot be run directly, only accessed from and EXE (or another DLL). An EXE is run from the operating system, which calls Main as the entry point. – Jasper Kent Mar 21 '20 at 11:45
I have another main in the data layer. and removing this causes more errors – Lebea Tshwarelo Tevin Kdot Mar 21 '20 at 12:00
Depends how you remove it. I would simply rename it, because calling it Main will only cause confusion. – Jasper Kent Mar 21 '20 at 12:50

Layer cannot access the methods used in the layer it references

1 Answers1