Question

I have this method, it selects data in a particular range (pageIndex and pageSize)

public PagedList(IQueryable<T> source, int pageIndex, int pageSize)
    {            
        this.AddRange(source.Skip(pageIndex * pageSize).Take(pageSize).ToList());
    }

I want to create an overloading method which selects all data, so, here’s my code

public PagedList(IQueryable<T> source)
    {
       //this.AddRange(source.Select(x => new T()).ToList()); (1)
        this.AddRange(source.AsQueryable().ToList()); (2)
    }

Firstly, I tried (1), but it didn’t accept T. Then I tried (2), and it’s recommended that I should make parameter type INumerable instead of IQueryable. What is the solution to select all data in this case?

Thanks

Answer 1

You can do it simply like this:

public PagedList(IEnumerable<T> source) 
{ 
    this.AddRange(source);
}

• IEnumerable<T> as parameter type instead of IQueryable<T>, because you don’t use any features specific to IQueryable<T>.
• No AsQueryable because you simply want all data
• No ToList as List<T>.AddRange internally already performs a copy. With ToList there would be two copy operations going on.