Question

So I posted this earlier.:
IAsyncRepository or IObservableRepository for silverlight 4 + WCF Data Services

I’ve been working on an AsyncRepo for Silverlight so I’ve just got stuck at a small place.

The code is just for the explanation…scroll to bottom for the culprit code.

I have a repo defined like this:

public interface IAsyncRepository<T> where T : class
{
    void GetById(int id, Action<T> callback);
    void GetAllFromQuery(Func<MyEntities, IQueryable<Product>> funcquery, Action<IList<Calculator>> callback)
}

I’m using WCF Data Services + Linq to Entities. The first one works perfect like this:

    public void GetById(int id, Action<Product> callback)
    {
        MyEntities dat = new MyEntities(new Uri(..url..));
        var query = from c in dat.Products where c.ID == id select c;//WATCH THIS
        allQuery = new DataServiceCollection<Product>(dat);
        allQuery.LoadAsync(query);
        allQuery.LoadCompleted += (obj, evt) =>
            {
                if (allQuery == null)
                {
                    callback(null);
                }
                else
                {
                    callback(allQuery.FirstOrDefault());
                }
            };
    }

Now to the second method:

If you notice in the above method, I have a linq query I use to get the data. In my second repo method, I want to pass this query from the consumer into the method.

So now..

    public void GetAllFromQuery(Func<MyEntities, IQueryable<Product>> funcquery, Action<IList<Product>> callback)
    {
        MyEntities dat = new MyEntities(..uri..);
        allQuery = new DataServiceCollection<Product>(dat);
        allQuery.LoadAsync(funcquery(dat));
        allQuery.LoadCompleted += (obj, evt) =>
        {
            if (allCalcQuery == null)
            {
                callback(null);
            }
            else
            {
                callback(allQuery.ToList());
            }
        };
    }

No problem so far… until…

I use it like this:

        repo.GetAllFromQuery(
            x => from p in x.Products where p.ID > 5 select p,
            y => Assert.IsTrue(y.Count > 0));

This gives me :

cannot convert from 'lambda expression' to System.Func<MyEntities,IQueryable<Product.Calculator>>'

I will truly respect someone who gives me any solution. This has given me programmers block all day today!

Answer 1

EDIT: Okay, now the typo’s fixed, try the non-query version (which I think is simpler anyway):

repo.GetAllFromQuery(
    x => x.Products.Where(p => p.ID > 5),
    y => Assert.IsTrue(y.Count > 0));