Entity Framework 4 - What is the syntax for joining 2 tables then paging them?

Question

I have the following linq-to-entities query with 2 joined tables that I would like to add pagination to:

IQueryable data = from inventory         


        

Answer 1

My answer here based on the answer that is marked as true but here I add a new best practice of the code above

    var data= (from c in db.Categorie.AsQueryable().Join(db.CategoryMap,
                    cat=> cat.CategoryId, catmap => catmap.ChildCategoryId, 
    cat, catmap) => new { Category = cat, CategoryMap = catmap })
select (c => c.Category)

this is the best practice to use the Linq to entity because when you add AsQueryable() to your code; system will converts a generic System.Collections.Generic.IEnumerable to a generic System.Linq.IQueryable which is better for .Net engine to build this query at run time

thank you Mr. Khumesh Kumawat

Answer 2

Define the join in your mapping, and then use it. You really don't get anything by using the Join method - instead, use the Include method. It's much nicer.

var data = objContext.ProductInventory.Include("Variant")
               .Where(i => i.ProductId == productId && i.StoreId == storeId)
               .OrderBy(j => j.Variant.SortOrder)
               .Skip(x)
               .Take(y);

Answer 3

You would simply use your Skip(itemsInPage * pageNo).Take(itemsInPage) to do paging.

Answer 4

Add following line to your query

var pagedQuery = data.Skip(PageIndex * PageSize).Take(PageSize); 

The data variable is IQueryable, so you can put add skip & take method on it. And if you have relationship between Product & Variant, you donot really require to have join explicitly, you can refer the variant something like this

IQueryable<ProductInventory> data = 
             from inventory in objContext.ProductInventory
             where inventory.ProductId == productId && inventory.StoreId == storeId
             orderby inventory.variant.SortOrder
             select new()
             {
                 property1 = inventory.Variant.VariantId,
                 //rest of the properties go here
             }
pagedQuery = data.Skip(PageIndex * PageSize).Take(PageSize);