How to use Dynamic LINQ in MVC4?

问题

This is the default action from the "View" of my MVC4 application.

public ActionResult Index(string sort = "R_ResDate", 
                          string sortdir = "DESC", 
                          int page = 1)
{
    List<Result> results = modRes.Results.ToList();

    var results = from r in results
                  orderby r.R_ResultDate descending
                  select r;

    return View(results);
}

Where modRes is a Model class,

I wanted to use the sort column, sortDir, and page arguments in the dynamic linq to derive the results.

Any help would be appreciated.

回答1:

You can use this code for paging and sorting data:

var p = Expression.Parameter(typeof(Model));
var sortByFunc = Expression.Lambda<Func<Model, object>>(Expression.TypeAs(Expression.Property(p, sortByKey), typeof(object)), p).Compile();

var items = from r in modRes.Results
            orderby r.R_ResultDate descending
            select r;
var orderedItems = sortByAsc 
      ? items.OrderBy(sortByFunc) 
      : items.OrderByDescending(sortByFunc);
var results = orderedItems.Skip((pageIndex - 1) * pageSize).Take(pageSize);

return View(results);

Also, you shouldn't to call ToList method on modRes.Results query, because in this case will be loaded all data, when only data for one page should be loaded.

来源：https://stackoverflow.com/questions/22005488/how-to-use-dynamic-linq-in-mvc4