c# - IEnumreable 动态和 lambda

Question

我想在 IEnumerable<dynamic> 上使用 lambda 表达式类型，但是我在使用新的 lambda 表达式的属性和坐标上遇到以下错误:

Cannot use a lambda expression as an argument to a dynamically dispatched operation without first casting it to a delegate or expression tree type .

这是我的代码

public static object returnFullSelectWithCoordinates(IEnumerable<dynamic> q)
        {
            return q.Select(b => new
            {
                route_id = b.b.route_id,
                name = b.b.name,
                description = b.b.description,
                attributes = b.b.route_attributes.Select(c => c.route_attribute_types.attribute_name),
                coordinates = b.b.coordinates.Select(c => new coordinateToSend { sequence = c.sequence, lat = c.position.Latitude, lon = c.position.Longitude })

            });

是否有任何解决方法可以使我的方法起作用？

Answer 1

自 Select<>是一种扩展方法，它不适用于动态类型。

使用 Enumerable.Select<> 可以获得相同的结果.

试试这个查询:

Enumerable.Select(q,(Func<dynamic,dynamic>)(b => new
        {
            route_id = b.b.route_id,
            name = b.b.name,
            description = b.b.description,
            attributes = b.b.route_attributes.Select(c => c.route_attribute_types.attribute_name),
            coordinates = b.b.coordinates.Select(c => new coordinateToSend { sequence = c.sequence, lat = c.position.Latitude, lon = c.position.Longitude })

        });