c# - 如何按 double 值对 List<T> 进行排序？

Question

这听起来很简单，但没那么简单。

我想根据 T 的一个属性来排序一个 List，它是 double 类型。

Answer 1

如果你在编译前知道属性名:

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

或

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

---

如果您在编译时没有该属性(例如在网格中进行动态排序等)；尝试以下扩展方法:

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;
    }
}

然后点赞

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