如何排序列表< T>双价值？ [英] How to sort a List<T> by double value?

问题描述

这听起来似乎很简单，但并不多。

This sound simple but it not that much.

我要订​​购基于T，这是double类型的属性之一列表。

I want to order a List based on one of the properties of T, which is double type.

推荐答案

如果您知道在编译之前的PROPERTYNAME：

If you know the propertyname before compilation:

myList = myList.OrderBy(a=>a.propertyName).ToList();

或

myList = (from m in myList order by m.propertyName).ToList();

---

如果你没有在编译的财产时间（在一个网格或东西如动态排序）;试试下面的扩展方法：

---

If you don't have the property at compile time (e.g. dynamic sorting in a grid or something); try the following extension methods:

static class OrderByExtender
{
    public static IOrderedEnumerable<T> OrderBy<T>(this IEnumerable<T> collection, string key, string direction)
    {
        LambdaExpression sortLambda = BuildLambda<T>(key);

        if(direction.ToUpper() == "ASC")
            return collection.OrderBy((Func<T, object>)sortLambda.Compile());
        else
            return collection.OrderByDescending((Func<T, object>)sortLambda.Compile());
    }

    public static IOrderedEnumerable<T> ThenBy<T>(this IOrderedEnumerable<T> collection, string key, string direction)
    {
        LambdaExpression sortLambda = BuildLambda<T>(key);

        if (direction.ToUpper() == "ASC")
            return collection.ThenBy((Func<T, object>)sortLambda.Compile());
        else
            return collection.ThenByDescending((Func<T, object>)sortLambda.Compile());
    }

    private static LambdaExpression BuildLambda<T>(string key)
    {
        ParameterExpression TParameterExpression = Expression.Parameter(typeof(T), "p");
        LambdaExpression sortLambda = Expression.Lambda(Expression.Convert(Expression.Property(TParameterExpression, key), typeof(object)), TParameterExpression);
        return sortLambda;
    }
}

再下订单像

Then order like

myList = myList.OrderBy("propertyName", "ASC").ToList();

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