Nested classes lists LINQ

Question

I have the following classes:

public class SerializedDelegate
{
    public List<GOEntry> goEntries = new List<GOEntry>();
}
public class GOEntry
{
    public string go;
    public List<MBEntry> mbEntries = new List<MBEntry>();
}
public class MBEntry
{
    public string mb;
    public List<MethodEntry> methodsEntries = new List<MethodEntry>();
}
public class MethodEntry
{
    public string method;
}

And this data:

var sd = new SerializedDelegate();
var eGo1 = new GOEntry { go = "Player1" };
var eGo2 = new GOEntry { go = "Player2" };
var eMb1 = new MBEntry { mb = "MB1" };
var eMb2 = new MBEntry { mb = "MB2" };
var eM1 = new MethodEntry { method = "target1" };
var eM2 = new MethodEntry { method = "target2" };
var eM3 = new MethodEntry { method = "target3" };
var eM4 = new MethodEntry { method = "target4" };
eMb1.methodsEntries.Add(eM1);
eMb1.methodsEntries.Add(eM2);
eMb2.methodsEntries.Add(eM3);
eMb2.methodsEntries.Add(eM4);
eGo1.mbEntries.AddRange(new[] { eMb1, eMb2 });
eGo2.mbEntries.Add(eMb1);
sd.goEntries.AddRange(new[] { eGo1, eGo2 });

What I'm trying to do - is print them in the following form:

     Player1: MB1.target1
     Player1: MB1.target2
     Player1: MB2.target3
     Player1: MB2.target4
     Player2: MB1.target1
     Player2: MB1.target2

I have printed them using foreach loops:

foreach (var goEntry in sd.goEntries) {
    foreach (var mbEntry in goEntry.mbEntries) {
        foreach (var methodEntry in mbEntry.methodsEntries)
            Console.WriteLine(goEntry.go + ": " + mbEntry.mb + "." + methodEntry.method);
    }
}

But I want to do it in a LINQ way - I want to construct a LINQ structure that corresponds to how I want to print them - so that I only need one foreach loop (so the length of the constructed enumerable is the number of total methods - in this case, 6).

I started like this - but no idea how to proceed further:

var entries = sd.goEntries
    .Select(g => new
    {
        GO = g.go,
        MBs = g.mbEntries,
        Methods = g.mbEntries.SelectMany(e => e.methodsEntries)
    });

Eventually, those method entries will be in a popup - so that's why I need a structure, that through out I could easily tell which MBEntry belongs to which GOEntry, and what MethodEntry belongs to which MBEntry.

Sorry if I wasn't clear enough - if that's the case, please say so.

Thanks.

Sergey Berezovskiy · Accepted Answer · 2014-04-04 15:28:00Z

1

var entries = from goEntry in sd.goEntries
              from mbEntry in goEntry.mbEntries
              from methodEntry in mbEntry.methodsEntries
              select new { goEntry.go, mbEntry.mb, methodEntry.method };

You can output entries this way:

 foreach(var entry in entries)
    Console.WriteLine("{0}: {1}.{2}", entry.go, entry.mb, entry.method);

edited Apr 4, 2014 at 15:28

answered Apr 4, 2014 at 15:21

Sergey Berezovskiy

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5 Comments

vexe Over a year ago

Thank you! - ahh, I missed that. Could you please post the long dotted linq extension methods format?

Sergey Berezovskiy Over a year ago

@vexe it will not be that beautiful, because you will need to use intermediate anonymous objects and SelectMany methods

vexe Over a year ago

ahh... which explains why I had troubles with it... It seems that I have to use the SQL format more often.

Chris Over a year ago

@SergeyBerezovskiy: You don't need any more anonymous objects than in your example, it just doesn't read anywhere near as well (see my answer for implementation).

Sergey Berezovskiy Over a year ago

@Chris I know, thats why I deleted my update. Anyway - I would go with query syntax here

Jon Skeet · Accepted Answer · 2014-04-04 15:21:56Z

It sounds like you want something like:

var lines = from goEntry in sd.goEntries
            from mbEntry in goEntry.mbEnties
            from methodEntry in mbEntry.methodsEntries
            select string.Format("{0}: {1}.{2}",
                                 goEntry.go, mbEntry.mb, methodEntry.method);

foreach (var line in lines)
{
    Console.WriteLine(line);
}

Or if you'd rather do the formatting later:

var entries = from goEntry in sd.goEntries
              from mbEntry in goEntry.mbEnties
              from methodEntry in mbEntry.methodsEntries
              select new { goEntry, mbEntry, methodEntry };

foreach (var entry in entries)
{
    Console.WriteLine("{0}: {1}.{2}", entry.goEntry.go,
                      entry.mbEntry.mb, entry.methodEntry.method);
}

... or capture the individual values to format (goEntry.go etc) as per Sergey's answer. Lots of different approaches :)

Chris · Accepted Answer · 2014-04-04 15:27:46Z

1

Others have given nicer looking answers but since you asked in an other comment for the method version of it I present it here:

sd.goEntries.SelectMany(
    ge=>ge.mbEntries.SelectMany(
        mb=>mb.methodsEntries.Select(
            me=>new {me.method, mb.mb, ge.go}
        )
    )
)

It is much harder to see what this is doing than the query syntax style as demonstrated by two other current answers.

answered Apr 4, 2014 at 15:27

Chris

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1 Comment

vexe Over a year ago

Thanks for the answer - yea, it's very cumbersome.

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