Question
Assuming these objects...
class MyClass
{
int ID {get;set;}
string Name {get;set;}
List<MyOtherClass> Things {get;set;}
}
class MyOtherClass
{
int ID {get;set;}
string Value {get;set;}
}
How do I perform a LINQ to Entities Query, using a projection like below, that will give me a List? This works fine with an IEnumerable (assuming MyClass.Things is an IEnumerable, but I need to use List)
MyClass myClass = (from MyClassTable mct in this.Context.MyClassTableSet
select new MyClass
{
ID = mct.ID,
Name = mct.Name,
Things = (from MyOtherClass moc in mct.Stuff
where moc.IsActive
select new MyOtherClass
{
ID = moc.ID,
Value = moc.Value
}).AsEnumerable()
}).FirstOrDefault();
Thanks in advance for the help!
Accepted Answer
You don't. You have to do this part in L2O.
So you could do:
var q = (from MyClassTable mct in this.Context.MyClassTableSet
select new // note anonymous type; important!
{
ID = mct.ID,
Name = mct.Name,
Things = (from MyOtherClass moc in mct.Stuff
where moc.IsActive
select new MyOtherClass
{
ID = moc.ID,
Value = moc.Value
}
}).AsEnumerable();
MyClass myClass = (from mct in q
select new MyClass
{
ID = mct.ID,
Name = mct.Name,
Things = mct.Things.ToList()
}).FirstOrDefault();
There's no way to do this in one query.
Popular Answer
I'm not sure what exactly your asking about, but List<T> does implement IEnumerable<T> (which is just an interface for an enumerable sequence).
A code that will do your projection and have Things be a List instead of an IEnumerable would use the ToList() operator, which creates a List<T> from any IEnumerable<T> this:
MyClass myClass = (from MyClassTable mct in this.Context.MyClassTableSet
select new MyClass
{
ID = mct.ID,
Name = mct.Name,
Things = (from MyOtherClass moc in mct.Stuff
where moc.IsActive
select new MyOtherClass
{
ID = moc.ID,
Value = moc.Value
}).ToList()
}).FirstOrDefault();
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