Flatten data using linq

Question

public class A
{
    public string Value1 { get; set; }
    public int Value2 { get; set; }
    public List<B> Values { get; set; }
    public int Value3 { get; set; }          
}

public class B
{
    public int Id { get; set; }
    public string X { get; set; }
}

public class Result
{
    public string Value1 { get; set; }
    public int Value2 { get; set; }
    public string ValueB1X { get; set; }
    public string ValueB2X { get; set; }
    ...
    public string ValueBnX { get; set; }
    public int Value3 { get; set; }  
}

I need to convert List of A into List of Result. Any idea how can that be done with LINQ? Basically what I need is this:

A[0] = |Value1|Value2|Value2|
        B[0]
        B[1]
        B[2]

A[1] = |Value1|Value2|Value2|
        B[0]
        B[1]
        B[2]

converted to

              +------------------------------------------------------+
     rowA[0]  | Value1 | Value2 |  B[0].X | B[1].X | B[1].X | Value3 |
     rowA[1]  | Value1 | Value2 |  B[0].X | B[1].X | B[1].X | Value3 |

Are there always going to be exactly three items in the list of Bs? — SimonC
– SimonC, Commented Sep 20, 2011 at 2:26

Kirk Broadhurst · Accepted Answer · 2011-09-20 02:46:48Z

1

You need to know how many B you will have, because the Result class needs to be written to accomodate that number of items. So this is not a dynamic solution that would work any number of B like you seem to imply (1..n)

A better design would be

public class Result 
{
    public string Value1 { get; set; }     
    public int Value2 { get; set; }     
    public List<B> BValues { get; set; }
}

or, assuming the B Ids are always unique,

public class Result 
{
    public string Value1 { get; set; }     
    public int Value2 { get; set; }     
    public Dictionary<int, string> BValues { get; set; }
}

and then construct a dictionary -

List<A> list = GetList();
List<Result> result = list.Select(a =>
    new Result()
    {
        Value1 = a.Value1,
        Value2 = a.Value2,
        BValues = a.Values.ToDictionary(b => b.Id, b => b.X)
    });

answered Sep 20, 2011 at 2:46

Kirk Broadhurst

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2 Comments

Pet Mor Over a year ago

Your Result class looks very similar to Class A that I started with. (except now its a Dictionary). Also I don't need IDs from class B, just Xs. (I added IDs just to show that B is complex class) What I really need is list of class B separated into variables and added to class A in the Result. Result class can be anonymous.

Kirk Broadhurst Over a year ago

You can't dynamically create concrete types in a strongly typed language. You can easily put all the Xs into a collection - list, dictionary, etc - but you can't dynamically create properties. A good question to you would be why? How are you going to use this Result object?

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