I found an interesting blog about how to do this in http://elegantcode.com/2009/12/15/entity-framework-ef4-generic-repository-and-unit-of-work-prototype/
The first step is to add the Interface:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Linq.Expressions;
using System.Data.Objects;
using System.Data;
namespace DAL
{
public interface IRepository2<T> : IDisposable where T : class
{
IQueryable<T> Fetch();
IEnumerable<T> GetAll();
IEnumerable<T> Find(Func<T, bool> predicate);
T Single(Func<T, bool> predicate);
T First(Func<T, bool> predicate);
void Add(T entity);
void Delete(T entity);
void Attach(T entity);
void SaveChanges();
void SaveChanges(SaveOptions options);
}
}
Next implementing the interface:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Linq.Expressions;
using System.Data.Objects;
using System.Data;
//http://elegantcode.com/2009/12/15/entity-framework-ef4-generic-repository-and-unit-of-work-prototype/
//
namespace DAL
{
/// <summary>
/// A generic repository for working with data in the database
/// </summary>
/// <typeparam name="T">A POCO that represents an Entity Framework entity</typeparam>
public class DataRepository<T> : IRepository2<T> where T : class
{
/// <summary>
/// The context object for the database
/// </summary>
private ObjectContext _context;
/// <summary>
/// The IObjectSet that represents the current entity.
/// </summary>
private IObjectSet<T> _objectSet;
/// <summary>
/// Initializes a new instance of the DataRepository class
/// </summary>
public DataRepository()
: this(new RESEARCH_CMEntities())
{
}
/// <summary>
/// Initializes a new instance of the DataRepository class
/// </summary>
/// <param name="context">The Entity Framework ObjectContext</param>
public DataRepository(ObjectContext context)
{
_context = context;
_objectSet = _context.CreateObjectSet<T>();
}
/// <summary>
/// Gets all records as an IQueryable
/// </summary>
/// <returns>An IQueryable object containing the results of the query</returns>
public IQueryable<T> Fetch()
{
return _objectSet;
}
public IQueryable<T> GetQuery() { return _objectSet; }
/// <summary>
/// Gets all records as an IEnumberable
/// </summary>
/// <returns>An IEnumberable object containing the results of the query</returns>
public IEnumerable<T> GetAll()
{
return GetQuery().AsEnumerable();
}
/// <summary>
/// Finds a record with the specified criteria
/// </summary>
/// <param name="predicate">Criteria to match on</param>
/// <returns>A collection containing the results of the query</returns>
public IEnumerable<T> Find(Func<T, bool> predicate)
{
return _objectSet.Where<T>(predicate);
}
/// <summary>
/// Gets a single record by the specified criteria (usually the unique identifier)
/// </summary>
/// <param name="predicate">Criteria to match on</param>
/// <returns>A single record that matches the specified criteria</returns>
public T Single(Func<T, bool> predicate)
{
return _objectSet.Single<T>(predicate);
}
/// <summary>
/// The first record matching the specified criteria
/// </summary>
/// <param name="predicate">Criteria to match on</param>
/// <returns>A single record containing the first record matching the specified criteria</returns>
public T First(Func<T, bool> predicate)
{
return _objectSet.First<T>(predicate);
}
/// <summary>
/// Deletes the specified entitiy
/// </summary>
/// <param name="entity">Entity to delete</param>
/// <exception cref="ArgumentNullException"> if <paramref name="entity"/> is null</exception>
public void Delete(T entity)
{
if (entity == null)
{
throw new ArgumentNullException("entity");
}
_objectSet.DeleteObject(entity);
}
/// <summary>
/// Deletes records matching the specified criteria
/// </summary>
/// <param name="predicate">Criteria to match on</param>
public void Delete(Func<T, bool> predicate)
{
IEnumerable<T> records = from x in _objectSet.Where<T>(predicate) select x;
foreach (T record in records)
{
_objectSet.DeleteObject(record);
}
}
/// <summary>
/// Adds the specified entity
/// </summary>
/// <param name="entity">Entity to add</param>
/// <exception cref="ArgumentNullException"> if <paramref name="entity"/> is null</exception>
public void Add(T entity)
{
if (entity == null)
{
throw new ArgumentNullException("entity");
}
_objectSet.AddObject(entity);
}
/// <summary>
/// Attaches the specified entity
/// </summary>
/// <param name="entity">Entity to attach</param>
public void Attach(T entity)
{
_objectSet.Attach(entity);
}
/// <summary>
/// Saves all context changes
/// </summary>
public void SaveChanges()
{
_context.SaveChanges();
}
/// <summary>
/// Saves all context changes with the specified SaveOptions
/// </summary>
/// <param name="options">Options for saving the context</param>
public void SaveChanges(SaveOptions options)
{
_context.SaveChanges(options);
}
/// <summary>
/// Releases all resources used by the WarrantManagement.DataExtract.Dal.ReportDataBase
/// </summary>
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
/// <summary>
/// Releases all resources used by the WarrantManagement.DataExtract.Dal.ReportDataBase
/// </summary>
/// <param name="disposing">A boolean value indicating whether or not to dispose managed resources</param>
protected virtual void Dispose(bool disposing)
{
if (disposing)
{
if (_context != null)
{
_context.Dispose();
_context = null;
}
}
}
}
}
I hear the sounds of Champaign glasses, so, Merry Christmas…
