EF.GenericRepository

A generic repository for Entity Framework written in C#.

Build Status :

Yes, I know, there are other generic implementations out there, but what I found hard to achieve with the other ones is managing object graphs. You know, you have a student and you want to add new classes etc etc. Sooner or later, once you start moving outside the basic CRUD functionalities of atomic objects, you are faced with the issue of object state management, especially in case of disconnected entities.

What this simple implementation attempts to do, is give developers a safe and efficient way for managing object state in Entity Framework. The generic repository comes with a UnitOfWork class which is your main class for querying and interacting with the database. Since it is a proper UoW implementation, operations can be bundled together so you don't have to call Save() per CRUD action.

For example the following operations can be performed before calling Save():

• pull an entity
• perform some updates to its properties
• add an item in the collection
• call Save() to persist in the database

This will make your code more efficient and will reduce the calls to the database. Win-win!

How to use EF.GenericRepository

To add the EF.GenericRepository to your project, either get the source from here or use NuGet. Please use NuGet!

Once you add the binary to your solution, you need to implement your DbContext and your data model objects and you can start interacting with the database

1. Set up

1.1 Basic Context Example

public class TestContext : DbContext, IDbContext
{
    static TestContext()
    {
        Database.SetInitializer<TestContext>(null);
    }

    public TestContext()
        : base("DefaultConnection")
    {
        ConnectionString = Database.Connection.ConnectionString;
    }

    public TestContext(string connectionString)
        : base(connectionString)
    {
        ConnectionString = Database.Connection.ConnectionString;
    }

    public string ConnectionString { get; private set; }

    public new IDbSet<T> Set<T>() where T : class
    {
        return base.Set<T>();
    }

    public override int SaveChanges()
    {
        this.ApplyStateChanges();
        return base.SaveChanges();
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        modelBuilder.Configurations.Add(new OwnerMap());
        modelBuilder.Configurations.Add(new PropertyMap());
        modelBuilder.Configurations.Add(new PropertyFeatureMap());
        modelBuilder.Configurations.Add(new PropertyImageMap());
    }
}

The concrete context needs to derive from DbContext and implement the IDbContext interface, which is part of the EF.GenericRepository project. The context constructor accepts either a "Default" connection string, which can be defined in or a user specified one. In addition, it exposes the connection string so that you can easily access it in your unit/integration tests.

1.2 Basic POCO example with EF Code-First

public class Owner : EntityBase
{
    public Owner()
    {
        Properties = new Collection<Property>();
    }

    public int OwnerId { get; set; }

    public string Address { get; set; }

    public string FullName { get; set; }

    public string Telephone1 { get; set; }

    public string Telephone2 { get; set; }

    public bool IsAgency { get; set; }

    public string LandlordRegNumber { get; set; }

    public bool HasDepositAccount { get; set; }
}

This is one of the classes in the data model. As long as any class derives from EntityBase, it can work with the EF.GenericRepository. Remember that you also need to define the EF specific properties either through the fluent API or the data annotations. An example of such map is provided below:

1.3 Poco Map for Entity Framework

public class OwnerMap: EntityTypeConfiguration<Owner>
{
    public OwnerMap()
    {
        HasKey(t => t.OwnerId);
        Property(t => t.FullName).IsRequired().HasMaxLength(500);
        Property(t => t.Telephone1).IsRequired().HasMaxLength(500);
        Property(t => t.Address).IsRequired();
        Property(t => t.Telephone2).HasMaxLength(500);
        Property(t => t.LandlordRegNumber).HasMaxLength(500);

        ToTable("Owner");
    }
}

2. Using the UnitOfWork for CRUD operations

2.1 Create/insert new object

var object = new ConcreteObject()
object.State = ObjectState.Added;
unitOfWork.Repository<ConcreteObject>().Insert(object);
unitOfWork.Save();

2.2 Create/Insert new object graph

var parent = new ParentObject();
parent.State = ObjectState.Added;
var child = new ChildObject();
child.Parent = parent;
child.State = ObjectState.Added;
unitOfWork.Repository<ChildObject>().InsertGraph(child);
unitOfWork.Save();

2.3 Update object

var objectToUpdate = unitOfWork.Repository<ConcreteObject>.Find(someObjectId);
objectToUpdate.SomeProperty = "new value"
objectToUpdate.State = ObjectState.Modified;
unitOfWork.Repository<ConcreteObject>.Update(objectToUpdate);
unitOfWork.Save();

2.4 Delete object

var objectToDelete = unitOfWork.Repository<ConcreteObject>.Find(someObjectId);
objectToUpdate.State = ObjectState.Deleted;
unitOfWork.Repository<ConcreteObject>.Delete(objectToUpdate);
unitOfWork.Save();

2.5 Querying objects

var result = unitOfWork.Repository<ConcreteObject>.Query().Filter(o =>o.objectId = thisId).Get().First();

For more examples on how to use the code, you can have a look in the EF.GenericRepository.Test or head to my blog post where I explain in a bit more detail the thinking behind this project - link