I've a data structure of something like this:
class A
{
List<B> data;
}
class B
{
C data;
}
class C
{
List<E> data;
}
class E
{
int Id;
string Name;
}
function GetEById(int id, List<A> data)
{
}
Now I need to build a Linq Lambda Expression where Id = something. I don't want to go for nested loops.
Any help will be greatfull.
Assuming your classes look like this:
public class A
{
public List<B> Data { get; set; }
}
public class B
{
public C Data { get; set; }
}
public class C
{
public List<E> Data { get; set; }
}
public class E
{
public int Id { get; set; }
public string Name { get; set; }
}
You can create a method GetEById that uses Enumerable.SelectMany() to flatten the results and pick the first E object that matches the id with Enumerable.FirstOrDefault():
private static E GetEById(int id, IEnumerable<A> data)
{
return data
?.SelectMany(a => a?.Data?.SelectMany(b => b?.Data?.Data))
.FirstOrDefault(e => e?.Id == id);
}
Or you could collect all E objects into a IEnumerable<E> filtering with Enumerable.Where():
private static IEnumerable<E> GetAllEById(int id, IEnumerable<A> data)
{
return data
?.SelectMany(a => a?.Data?.SelectMany(b => b?.Data?.Data))
.Where(e => e?.Id == id);
}
You can try this on https://dotnetfiddle.net/
Note: You could also look into Null-conditional operators to ensure child properties don't execute if the parent property is null.
I would also name your class types better. Names such as A, B, C etc. don't really mean much, and makes it hard for the reader to understand what these classes do and represent.
?. after SelectMany as that will never return null.