如何將linq投影和項目用於根投影對象的子集合？

Question

林試圖做到這一點....

var entity = landingPages.Select(x = new MyClass { name = x.name, age = x.age }); 

唯一的問題是，年齡實際上是一個coolection所以我想我會做到這一點...

var entity = landingPages.Select(x = new MyClass { name = x.name, age.add(x.age) }); 

但它不工作。這可能嗎？

Answer 1

var entity = landingPages.Select(x => new MyClass 
{ //this is an initialization block. Only Property Assignment is allowed. 
    name = x.name, 
    age.add(x.age) //arbitrary statements are not allowed in initialization blocks. 
}); 

---

你沒有說哪個年齡是一個集合（的LandingPage的年齡​​或MyClass的年齡）。

如果是LandingPage的年齡​​，那麼：將單個值轉換爲集合。

IEnumerable<MyClass> query = landingPages.Select(x => new MyClass 
{ 
    name = x.name, 
    age = new List<int>() { x.age } //this is a collection initializer 
}); 

如果是MyClass的年齡，那麼：將集合轉換爲單個值。

IEnumerable<MyClass> query = landingPages.Select(x => new MyClass 
{ 
    name = x.name, 
    age = x.age.Sum() 
});