如何动态排序结果

Question

我正在尝试动态应用排序。我正在使用 EntityFramework。我正在传递 sortorder 和 sortfield。现在我不想写条件来按 sortfield 列排序结果。我试过的如下，

    public static IOrderedQueryable<TSource> OrderByProperty<TSource, TKey>(this IQueryable<TSource> source, string property, string sortorder)
    {
        ParameterExpression param = Expression.Parameter(typeof(TSource), "t");
        MemberExpression member = Expression.Property(param, property);
        var ex = Expression.Lambda<Func<TSource, TKey>>(member, param);
        return source.OrderBy<TSource, TKey>(ex);
    }

我这样称呼它，

OrderByProperty<Class, dynamic>(objClass, sortfield, sortorder);

当 sortfield 的类型为 System.Int32 时，我遇到以下错误；

Expression of type 'System.Int32' cannot be used for return type 'System.Object'

string 相同。感谢您的帮助。

Answer 1

试试这个扩展方法：

  public static IQueryable<T> OrderByField<T>(this IQueryable<T> q, string SortField, bool Ascending)
  {
        var param = Expression.Parameter(typeof(T), "p");
        var prop = Expression.Property(param, SortField);
        var exp = Expression.Lambda(prop, param);
        string method = Ascending ? "OrderBy" : "OrderByDescending";
        Type[] types = new Type[] { q.ElementType, exp.Body.Type };
        var mce = Expression.Call(typeof(Queryable), method, types, q.Expression, exp);
        return q.Provider.CreateQuery<T>(mce);
   }

如何动态排序结果

How to order result dynamically

.net

c#

entity-framework

iqueryable