如何在连接两个表时将Linq中的匿名对象列表返回给Sql

Question

I have one requirement in which I have to perform a join on two tables and return a list of the returned rows using Linq to Sql.

public List<T> GetProductList()
{
    var popupList = (from p in this.Products
                     join c in this.Categories 
                     on p.CategoryID equals c.CategoryID
                     select new
                     {
                         ProductID = p.ProductID,
                         ProductName= p. ProductName,
                         CategoryID = c.CategoryID,
                         CategoryName = c.CategoryName,
                         DateCreated = p.DateCreated,
                         IsActive = p.IsActive
                     }).OrderBy(p => p.CategoryName);

    return popupList;
}

Is there any way to do this in C#?

Answer 1

You could declare a class, like below -:

public class ProductCategoryView
{
    public int ProductID        { get; set; }
    public strig ProductName    { get; set; }
    public int CategoryID       { get; set; }
    public string CategoryName  { get; set; }
    public DateTime DateCreated { get; set; }
    public bool IsActive        { get; set; }
}

which will have as properties the values you want to have each row of your join.

note I may be wrong of the types I choosed for some of your properties. So you have to correct them correspondingly.

Then you have to refactor your query:

public List<ProductCategoryView> GetProductList()
{
    var popupList = (from p in this.Products
                     join c in this.Categories 
                     on p.CategoryID equals c.CategoryID
                     select new JoinView
                     {
                         ProductID = p.ProductID,
                         ProductName= p. ProductName,
                         CategoryID = c.CategoryID,
                         CategoryName = c.CategoryName,
                         DateCreated = p.DateCreated,
                         IsActive = p.IsActive
                     }).OrderBy(p => p.CategoryName)
                       .ToList();
    return popupList;
}

Answer 2

I have also found a way of doing this using IQueryable return type. Could you suggest me the advantages and disadvantages of using IQueryable as return type for anonymous types.

public IQueryable GetProductList()
{
    var popupList = from p in this.Products
                     join c in this.Categories 
                     on p.CategoryID equals c.CategoryID
                     select new
                     {
                         ProductID = p.ProductID,
                         ProductName= p. ProductName,
                         CategoryID = c.CategoryID,
                         CategoryName = c.CategoryName,
                         DateCreated = p.DateCreated,
                         IsActive = p.IsActive
                     };
    return popupList.OrderBy(p => p.CategoryName);
}