Implementing a Generic Data Access Layer in ADO.NET Part 3

By : Joydip Kanjilal Jan 29, 2008

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In this the final article of this series, I will discuss the other classes in this framework and how we can use this framework to perform various CRUD operations in our applications.

Let us start from where we left off in the previous part of this series. Note that most of the methods of the DatabaseHelper class have been marked as “internal” to prevent them from being called outside of the “ApplicationFramework.DataAccessLayer” namespace.

Now we will come to the DBManager class; the wrapper class that encapsulates the calls to another class called DBHelper that actually performs the CRUD operations on the underlying database. The DBManager class extends the DBManagerBase abstract class. The DBManagerBase class contains the definition for the Open () and the Close () methods and some other public properties that are generic and can be used by any class that acts as a wrapper. We will have a look at the DBManagerBase class first.

The following code listing shows the DBManagerBase class.

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Configuration;
using System.Data.Common;
using System.Data.SqlClient;
using System.Data.OleDb;
using System.Data.Odbc;
using System.IO;

namespace ApplicationFramework.DataAccessLayer
{
    public abstract class DBManagerBase
    {
        protected DatabaseHelper databaseHelper = null;
        protected DbDataReader dbDataReader = null;
        protected DataSet dataSet = null;
        protected ProviderType providerType;
        protected String connectionString = String.Empty;
        protected bool isOpen = false;

        public bool IsOpen
        {
            get
            {
                return isOpen;
            }

            set
            {
                isOpen = value;
            }
        }

        public string ConnectionString
        {
            get
            {
                return connectionString;
            }

            set
            {
                connectionString = value;
            }
        }

        public DbConnection Connection
        {
            get
            {
                return databaseHelper.Connection;
            }
        }

        public DbCommand Command
        {
            get
            {
                return databaseHelper.Command;
            }
        }

        public ProviderType DBProvider
        {
            set
            {
                providerType = value;
            }

            get
            {
                return providerType;
            }
        }

        public DataSet DBSet
        {
            get
            {
                return dataSet;
            }
        }

        public DbDataReader DBReader
        {
            get
            {
                return dbDataReader;
            }
        }

        protected void Open(string connectionString)
        {
            databaseHelper = new DatabaseHelper(connectionString, DBProvider);
        }

        protected void Close()
        {
            if (dbDataReader != null)
                if (!dbDataReader.IsClosed)
                    dbDataReader.Close();
            databaseHelper.Dispose();
        }

        public void BeginTransaction()
        {
            databaseHelper.BeginTransaction();
        }

        public void CommitTransaction()
        {
            databaseHelper.CommitTransaction();
        }

        public void RollbackTransaction()
        {
            databaseHelper.RollbackTransaction();
        }
    }
}