Defining generic repository for entities in EF DatabaseFirst

Question

I am moving from CodeFirst to DatabaseFirst to map my views. In my CodeFirst approach I had a base entity like this:

public abstract class BaseEntity
{
    /// <summary>
    /// Gets or sets the entity identifier
    /// </summary>
    public virtual int Id { get; set; }
... // Some more methods here for equality checking
}

I derived all my classes from this base class, since every one of them would have an Id. So I used this BaseClass to create a generic repository. My repository looks like this:

public partial class EfRepository<T> where T : BaseEntity
{
    public readonly DemirbasContext context;
    private DbSet<T> _entities;

    /// <summary>
    /// Ctor
    /// </summary>
    /// <param name="context">Object context</param>
    public EfRepository(DemirbasContext context)
    {
        this.context = context;
    }

    public T GetById(object id)
    {
        return this.Entities.Find(id);
    }

    public void Insert(T entity)
    {
        try
        {
            if (entity == null)
                throw new ArgumentNullException("entity");

            this.Entities.Add(entity);

            this.context.SaveChanges();
        }
        catch (Exception e)
        {
        ...
        }
    }
    // Other methods here Update, Delete etc

So I was able to create repositories just by specifying the generic type paremeter like this

EfRepository<Car> carRepo = new EfRepository<Car>();

In DatabaseFirst, I cannot derive the entity classes from a base class. Is there a way to do it or what would be your suggestions?

score 0 · Accepted Answer · answered Jul 31 '12 at 08:16

Oops, I missed code generators.

Right click on your data model (.EDM file) and click Add Code Generation Item. Choose DbContext (for simplified DbContext API).

This creates two files with .tt extensions: One for context and one for entities. If you expand the file, you will see .tt file holds all your classes there.

You can modify it as you need.

Defining generic repository for entities in EF DatabaseFirst

1 Answers1