Creating a generic template in C#

Question

I have researched that C#, as well as its predecessor, C++, enable users to create generic templates.

Here are the two source code snippets below:

using System;
using System.Collections.Generic;
using System.Data.OleDb;
using System.IO;

namespace Access_mdb
{
    public class DataOperations
    {
        public static string ConnectionString =
            $"Provider=Microsoft.Jet.OLEDB.4.0;Data Source={Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "[DatabaseFileName].mdb")};";

        public static List<string> Read()
        {

            var list = new List<string>();

            using (var cn = new OleDbConnection() { ConnectionString = ConnectionString })
            {
                using (var cmd = new OleDbCommand() { Connection = cn })
                {
                    cmd.CommandText = "SELECT [FieldOne] FROM tblOne;";

                    cn.Open();

                    var reader = cmd.ExecuteReader();
                    while (reader.Read())
                    {
                        list.Add(reader.GetString(0));
                    }

                    cn.Close();
                }
            }
            return list;
        }
    }
}

and here is the second source code snippet below:

using System;
using System.IO;
using System.Data.OleDb;
using System.Collections.Generic;


namespace Access_mdb
{
    public class DataOpsTwo
    {
        public static string connectionstring = $"Provider=Microsoft.Jet.OLEDB.4.0;Data Source={Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "[DatabaseFileName.mdb]")};";

        public static List<string> ReadOne()
        {
            var listOne = new List<string>();

            using (var connection = new OleDbConnection() { ConnectionString = connectionstring })
            { 
            using (var cmdOle1 = new OleDbCommand() { Connection = connection })
                {
                    cmdOle1.CommandText = "SELECT [FieldOne] FROM tblTwo;";
                    connection.Open();
                    var readerOne = cmdOle1.ExecuteReader();
                    while (readerOne.Read())
                    {
                        listOne.Add(readerOne.GetString(0));
                    }
                    connection.Close();
                    }
                }
            return listOne;
            }
        }


    }

What I want to perform is to create a generic template, so that I do not have to perform double or repetitive work on creating different classes.

Is there any way or method on how to perform this effecitively?

Regards,

JohnCTX

Answer 1

Hi JohnCTX-6479,
First, you can add a new class in your project via following steps(as a template):
Right-click your project name->Add->Class->Change class name to DataOperations.cs
Then you need put the template code into DataOperations class.
In this step, I suggest you construct a function with parameters and pass in "ConnectionString" as a parameter.
Due to the Read method is static, so you can call it via class name directly.

class DataOperations  
{  
    public static string ConnectionString = $"Provider=Microsoft.Jet.OLEDB.4.0;Data Source={Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "[DatabaseFileName].mdb")};";  
  
    public static List<string> Read(string s)  
    {  
        var list = new List<string>();  
  
        using (var cn = new OleDbConnection() { ConnectionString = s })  
        {  
            using (var cmd = new OleDbCommand() { Connection = cn })  
            {  
                cmd.CommandText = "SELECT [FieldOne] FROM tblOne;";  
  
                cn.Open();  
  
                var reader = cmd.ExecuteReader();  
                while (reader.Read())  
                {  
                    list.Add(reader.GetString(0));  
                }  
  
                cn.Close();  
            }  
        }  
        return list;  
    }  
}  
  
  
public class DataOpsTwo  
{  
       public void test()   
       {  
             List <string> list= DataOperations.Read(DataOperations.ConnectionString);//you can also pass another connectionString  
        }  
}  

Best Regards,
Daniel Zhang

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