LINQ: Transforming items in a collection

Is there a LINQ method to modify items in a collection, such as simply setting a property of each item in a collection? Something like this:

var items = new []{ new Item { 开发者_JS百科IsActive = true } }
var items = items.Transform(i => i.IsActive = false)

where Touch enumerates each item and applies the transformation. BTW, I am aware of the SELECT extension method, but this would require I expose a method on the type that does this transformation and return the same reference.

var items = items.Select(i => i.Transform())

where Item.Transform returns does the transformation and return the same instance.

TIA

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No, there are no methods in standard LINQ that allows you to modify items in a collection. LINQ is for querying collections and not for causing side-effects (e.g., mutating the items). Eric Lippert goes into the idea in more detail in his blog post: “foreach” vs “ForEach”.

Just use a loop.

foreach (var item in items)
{
    item.IsActive = false;
}

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LINQ is for querying. Use a simple loop if you want to modify. Just use the right tool for the right job. LINQ is not a messiah for everything.

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There's a ForEach() on List, so you can do items.ToList().ForEach(i => i.IsActive = false). You might want to read this though.

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The documentation page on MSDN for the Enumerable class lists all LINQ methods, and unfortunately no method there does what you want. LINQ is a query language and is not intended to modify collections. It is functional in its nature, meaning that it doesn't modify the collection it operates on, rather it returns a new enumerable.

For your purposes it is better to simply use a foreach loop, or if you feel the need write your own extension method to do what you want, eg.

public static void ForEach<T>(this IEnumerable<T> seq, Action<T> action)
{
   foreach (T item in seq)
      action(item);
}

which could then be used as you wanted:

items.ForEach(i => i.IsActive = false)