Question

I have implemented Generic repository which only depends on IUnitOfWork (in Infrastructure.Repositories Library) and also haven’t used any references to Entity Framework 4.1 dll. Entity Framework’s DbContext wrapped with EFUnitOfWork which is in different class library called Infrastructure.EntityFramework. However, I came across some difficulty with Linq to Entity query that may force me to include direct dependancy with repository and EF 4.1 library.

In one of my class repository I need to use following query with a join. How can I overcome DBContext usage in my repository ?

var result = from cc in ProjectXEFDbContext.CurrentContext().PurchaseOrderLineItemCollection
                     join bb in GetQuery() on cc.PurchaseOrderId equals bb.Id
                     where bb.Id == purchaseOrder.Id && cc.Total > 50
                     select cc;

Answer 1

I made my repositories to expose IQuerables over DbContext. DbContext wrap with UnitOfWork as follows

My Repository base goes like this

    /// <summary>
    /// Gets the query.
    /// </summary>
    /// <returns></returns>
    public IQueryable<TEntity> GetQuery()
    {
        return this.UnitOfWork.GetQuery<TEntity>();
    }

    /// <summary>
    /// Loads the type.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <returns></returns>
    public IQueryable<T> LoadType<T>() where T : class
    {
        return this.UnitOfWork.GetQuery<T>();
    }

my unit of work implementation goes here

    /// <summary>
    /// Gets the query.
    /// </summary>
    /// <typeparam name="TEntity">The type of the entity.</typeparam>
    /// <returns></returns>
    public IQueryable<TEntity> GetQuery<TEntity>() where TEntity:class 
    {
        return this.DbContext.Set<TEntity>();
    }

Changes to my query as follows

        var result = from cc in GetQuery()
                     join bb in LoadType<PurchaseOrderLineItem>() on cc.Id equals                      bb.PurchaseOrderId
                     where cc.Id == purchaseOrder.Id && bb.Total > 50
                     select bb;