Get the item from a collection that contains another collection using linq

Question

Say I have a collection of Layer objects and each Layer may or may not contain a Polygon collection. There's only one Layer that contains the Polygon collection from the Layer collection. How do I obtain this Layer from the collection using LINQ?

Something like

foreach (var layer in Layers)
{
    var item = layer.FirstOrDefault( x =>x.Content is Polygon)
    if (item != null) return layer
}

Answer 1

您应该能够获得具有以下多边形内容的第一层：（使用Enumerable.Any ）：

return Layers.FirstOrDefault(l => l.Any(x => x.Content is Polygon));