I have a loop as follows:
foreach(x in myColl)
{
foreach(var y in x.MyList)
{
result.Add(x.MyKey + y)
}
}
That means within my inner loop I need access to a property of the current outer element.
I´m looking for a LINQ-statement but I´m unsure on it. I tried it by using
result = myColl
.SelectMany(x => x.MyList)
.SelectMany(x => /* how to get the key of the outer loop here */ + x)
This is easy with query expressions:
(from x in myColl
from y in x.MyList
select x.MyKey + y).ToList()
This works because this translates to:
myColl
.SelectMany(x => x.MyList.Select(item => new { List = x, Item = item }))
.Select(x => ...) //rest of the query, whatever you like
The key is to keep both the list as well as the list items. Channel them through the query using an anonymous type (or any other container).
SelectMany should just be a Select, or it's likely to translate to the SelectMany overload in Tormod's answer.SelectMany must receive a predicate which returns an IEnumerable and it doesn't...This is when I personally prefer query syntax
var result = from x in myCol1
from y in x.MyList
select x.MyKey + y;
There is an overload of SelectMany which allows access to the "parent" element. ListOfList.SelectMany(list=>list.InnerList,(lst,element)=> HandleInnerListAndElementFromIt(lst,element))
result = myColl.SelectMany(x => x.MyList,(x1,x2)=>DoSomething(x1,x2));
EDIT Added:
For your concrete example it looks like this:
result = myColl.SelectMany(x=>x.MyList,(x,y)=>x.MyKey+y));
Notice that there are two lambda parameters to the SelectMany method call.
First lambda will take the "x" and return a new Enumerable. x=>x.MyList
The second lambda takes the "x" and "y" and produce a new result. (x,y)=>x.MyKey+y
