Part 58 - Repository Pattern - 5 - Setting Up Generic Repository and UnitOfWork in Data Access Layer

In this tutorial, You will learn about how to Setup Generic Repository and UnitOfWork in Data Access Layer under repository pattern implementation in Asp.net MVC. 

So far, we were creating several Layers but now we will see how the actual repository get setup so that we can use its predefined methods without doing any change into this. In other words, making repository more generic. 

Lets have a quick review of all layers that we created in previous tutorial.

1. Web Layer is your MVC web Project
2.  Business Layer consist the CRUD operation, gets data from Data Access Layer, Manipulate them and finally returns data to the Controller ( Web Layer)
3. Domain Layer consist the Domain Models or Classes that hold the data coming from Data Access Layer. Both Web and Business Layer can use domain models to exchange data.
4. Data Access Layer consist the generic repository methods (generic CRUD operation), Unit of Work( Database Context) and NON Generic repository( User defined repository).

#How to Setup Generic Repository and UnitOfWork? 

 Please follow below Steps 

Step 1 : Adding  Interface and classes into Data Access Layer

 A.   Add Infrastructure Folder into Repository Layer. Inside this folder we are going to place our all Generic Repository Code.

B.  Add Contract folder into Infrastructure folder

C.  Add two interface into Contract folder i.e IBaseRepository.cs and IUnitOfWork.cs
D. Add concrete classes into Infrastructure folder i.e Add BaseRepository.cs and UnitOfWork.cs

Step 2 : Add generic code into above created files. 

A.  IBaseRepository.cs ( Interface) 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;

namespace MVCTutorial.Repository.Infrastructure
{
    public interface IBaseRepository<T>
    {
       
        /// <summary>
        /// Retrieve a single item by it's primary key or return null if not found
        /// </summary>
        /// <param name="primaryKey">Prmary key to find</param>
        /// <returns>T</returns>
        T SingleOrDefault(Expression<Func<T, bool>> whereCondition);

        /// <summary>
        /// Returns all the rows for type T
        /// </summary>
        /// <returns></returns>
        IEnumerable<T> GetAll();

        /// <summary>
        /// Returns all the rows for type T on basis of filter condition
        /// </summary>
        /// <returns></returns>
        IEnumerable<T> GetAll(Expression<Func<T, bool>> whereCondition);
               
        /// <summary>
        /// Inserts the data into the table
        /// </summary>
        /// <param name="entity">The entity to insert</param>
        /// <param name="userId">The user performing the insert</param>
        /// <returns></returns>
        T Insert(T entity);

        /// <summary>
        /// Updates this entity in the database using it's primary key
        /// </summary>
        /// <param name="entity">The entity to update</param>
        /// <param name="userId">The user performing the update</param>
        void Update(T entity);

        /// <summary>
        /// Updates all the passed entities in the database 
        /// </summary>
        /// <param name="entities">Entities to update</param>
        void UpdateAll(IList<T> entities);

        /// <summary>
        /// Deletes this entry fro the database
        /// ** WARNING - Most items should be marked inactive and Updated, not deleted
        /// </summary>
        /// <param name="entity">The entity to delete</param>
        /// <param name="userId">The user Id who deleted the entity</param>
        /// <returns></returns>
        void Delete(Expression<Func<T, bool>> whereCondition);
        
        /// <summary>
        /// Does this item exist by it's primary key
        /// </summary>
        /// <param name="primaryKey"></param>
        /// <returns></returns>
        bool Exists(Expression<Func<T, bool>> whereCondition);

    }
   
}

B.  IUnitOfWork( Interface) 

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MVCTutorial.Repository.Infrastructure
{
    public interface IUnitOfWork : IDisposable
    {
        /// <summary>
        /// Return the database reference for this UOW
        /// </summary>
        DbContext Db { get; }

    
    }
}

C. BaseRepository( Concrete Class)

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;

namespace MVCTutorial.Repository.Infrastructure
{
    /// <summary>
    /// Base class for all SQL based service classes
    /// </summary>
    /// <typeparam name="T">The domain object type</typeparam>
    /// <typeparam name="TU">The database object type</typeparam>
    public class BaseRepository<T> : IBaseRepository<T> where T : class
    {
        private readonly IUnitOfWork _unitOfWork;
        internal DbSet<T> dbSet;

        public BaseRepository(IUnitOfWork unitOfWork)
        {
            if (unitOfWork == null) throw new ArgumentNullException("unitOfWork");
            _unitOfWork = unitOfWork;
            this.dbSet = _unitOfWork.Db.Set<T>();
        }

        public T SingleOrDefault(Expression<Func<T, bool>> whereCondition)
        {
            var dbResult = dbSet.Where(whereCondition).FirstOrDefault();
            return dbResult;
        }
              
        public IEnumerable<T> GetAll()
        {
            return dbSet.AsEnumerable();
        }

        public IEnumerable<T> GetAll(Expression<Func<T, bool>> whereCondition)
        {
            return dbSet.Where(whereCondition).AsEnumerable();
        }

        public virtual T Insert(T entity)
        {

            dynamic obj = dbSet.Add(entity);
            this._unitOfWork.Db.SaveChanges();
            return obj;

        }

        public virtual void Update(T entity)
        {
            dbSet.Attach(entity);
            _unitOfWork.Db.Entry(entity).State = EntityState.Modified;
            this._unitOfWork.Db.SaveChanges();


        }

        public virtual void UpdateAll(IList<T> entities)
        {
            foreach (var entity in entities)
            {
                dbSet.Attach(entity);
                _unitOfWork.Db.Entry(entity).State = EntityState.Modified;
            }
            this._unitOfWork.Db.SaveChanges();
        }

        public void Delete(Expression<Func<T, bool>> whereCondition)
        {
            IEnumerable<T> entities = this.GetAll(whereCondition);
            foreach (T entity in entities)
            {
                if (_unitOfWork.Db.Entry(entity).State == EntityState.Detached)
                {
                    dbSet.Attach(entity);
                }
                dbSet.Remove(entity);
            }
            this._unitOfWork.Db.SaveChanges();
        }

        //--------------Exra generic methods--------------------------------

        public T SingleOrDefaultOrderBy(Expression<Func<T, bool>> whereCondition, Expression<Func<T, int>> orderBy, string direction)
        {
            if (direction == "ASC")
            {
                return dbSet.Where(whereCondition).OrderBy(orderBy).FirstOrDefault();

            }
            else
            {
                return dbSet.Where(whereCondition).OrderByDescending(orderBy).FirstOrDefault();
            }
        }

        public bool Exists(Expression<Func<T, bool>> whereCondition)
        {
            return dbSet.Any(whereCondition);
        }

        public int Count(Expression<Func<T, bool>> whereCondition)
        {
            return dbSet.Where(whereCondition).Count();
        }

        public IEnumerable<T> GetPagedRecords(Expression<Func<T, bool>> whereCondition, Expression<Func<T, string>> orderBy, int pageNo, int pageSize)
        {
            return (dbSet.Where(whereCondition).OrderBy(orderBy).Skip((pageNo - 1) * pageSize).Take(pageSize)).AsEnumerable();
        }

        public IEnumerable<T> ExecWithStoreProcedure(string query, params object[] parameters)
        {
            return dbSet.SqlQuery(query, parameters);
        }
    }
}

D. UnitOfWork( Concrete Class)  :  

Note: In below code MVCTutorialEntitiesContainer is db context/ Connection string name. You can copy the name from App.config File. 

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace MVCTutorial.Repository.Infrastructure
{
    public class UnitOfWork : IUnitOfWork
    {
        private readonly MVCTutorialEntitiesContainer _dbContext;

        public UnitOfWork()
        {
            _dbContext = new MVCTutorialEntitiesContainer();
        }

        public DbContext Db
        {
            get { return _dbContext; }
        }

        public void Dispose()
        {
        }
    }

}

What Next => In next tutorial we will learn  about how to  create Non Generic  Repository against each entity or database class. We will also learn how to perform CRUD operation over Generic Repository

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