Desired upload to .Net4 Link-to-EF; possibly like DataLoadOptions

Question

I am using VS2010.Net4 Linq-to-EntityFramework and would like to explicitly load some child data. I would like to provide functionality similar to the DataLoadOptions or LoadWith functions that are available for Linq-to-SQL IIUC but not available for Linq-to-EF.

(Aside, this is so that I can record data that will be played back later during testing. We used lazy loading and I need to find these occurrences and replace with impatience loading. DataLoadOptions would allow this method to be implemented.)

I am trying to provide a download scheme with the type of electronic download described in the MosesOfEgypt blog . I changed the generation of T4 and have what, in my opinion, is the last issue. In .Net4, object properties return an ObjectSet . But unfortunately, the Include function returns ObjectQuery , which is the base class for the ObjectSet .

Here is a subset of the ObjectContext class created from a modified T4 template:

    #region DataLoadOptions Functionality

            public DataLoadOptions LoadOptions { get; set; }

            private ObjectSet<TEntity> ApplyDataLoadOptions<TEntity>(string queryString) where TEntity : class
            {
                var query = CreateObjectSet<TEntity>(queryString);

                if (LoadOptions != null)
                {
                    var members = LoadOptions.GetPreloadedMembers<TEntity>();

                    foreach (var member in members)
                    {
 **********              query = query.Include(member.Name);
                    }
                }
                return query;
            }

    #endregion



    #region ObjectSet Properties

        /// <summary>
        /// No Metadata Documentation available.
        /// </summary>
        public ObjectSet<Address> Addresses
        {
            get
            {
                if ((_Addresses == null))
                {
                    _Addresses = ApplyDataLoadOptions<Address>("Addresses");
                }
                return _Addresses;
            }
        }

    #endregion

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DataLoadOptions Linq-to-EF .Net4 .

Answer 1

, .

.Include ObjectQuery<T>, IQueryable<T>. ObjectSet<T>??

WRT " " Include, - . .

( , ), . . Include.

() :

public ICollection<Order> GetOrdersWithUser(Expression<Func<Order,bool>> predicate, OrderAssocations[] includes)
{
   return _ctx.Orders.WithAssociations(includes).Where(predicate).ToList();
}

:

public static ObjectQuery<Order> WithAssociations(this ObjectQuery<Order> source, OrderAssociations[] includes)
{
   var query = source;

   foreach (var include in includes)
   {
      query = query.Include(include.ToNavigationalProperty()));
   }

   return query;
}

.ToNavigationalProperty() - , Navigational.

Answer 2

, ... , "" :

/// <summary>
    /// Flags to indicate which child entities to eager load
    /// </summary>
    [Flags]
    public enum IncludeFlags
    {
        None = 1,
        All = 1 << 1,
        ChildEntity1 = 1 << 2,
        ChildEntity2 = 1 << 3,
        ChildEntity3 = 1 << 4
    }

    /// <summary>
    /// Method to create my object query
    /// </summary>
    /// <param name="context">Database context</param>
    /// <param name="includeFlags">Indicates which flags to Include</param>
    /// <returns></returns>
    private static ObjectQuery<MyEntity> GetContext(DataBaseContext context, IncludeFlags includeFlags)
    {
        ObjectQuery<MyEntity> query = new ObjectQuery<MyEntity>("MyEntity", context);

        if ((includeFlags & IncludeFlags.None) != IncludeFlags.None)
        {
            bool getAll = ((includeFlags & IncludeFlags.All) == IncludeFlags.All);
            if (getAll || ((includeFlags & IncludeFlags.ChildEntity1) == IncludeFlags.ChildEntity1))
                query = query.Include("ChildEntity1");

            if (getAll || ((includeFlags & IncludeFlags.ChildEntity2) == IncludeFlags.ChildEntity2))
                query = query.Include("ChildEntity2");

            if (getAll || ((includeFlags & IncludeFlags.ChildEntity3) == IncludeFlags.ChildEntity3))
                query = query.Include("ChildEntity2.ChildEntity3");
        }

        return query;
    }

    public static MyEntity[] GetMyEntities(IncludeFlags flags = IncludeFlags.None)
    {
        DataBaseContext db = new DataBaseContext();
        from e in GetContext(db, flags)
        select e;

        return e.ToArray();
    }

    public void GetMyEntities()
    {
        MyEntity[] entities = Test.GetMyEntities(); // Does not load any child entities
        MyEntity[] entities2 = Test.GetMyEntities(IncludeFlags.All); // Loads them all
        MyEntity[] entities3 = Test.GetMyEntities(IncludeFlags.ChildEntity1 | IncludeFlags.ChildEntity2); // Only loads child 1 and 2
        MyEntity[] entities4 = Test.GetMyEntities(IncludeFlags.ChildEntity3); // Only loads ChildEntity2.ChildEntity3
    }

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