C# - how to write a collection (Dictionary?) with one key and two values

Question

What's the easiest way to create a collection of key, value1, value2 ?

Important to me is that it is easy & short to retrieve either value1 or value2 given the pair (please show an example)

I know I can do this -

class MyObject
{
    internal string NameA { get; set; }
    internal string NameB { get; set; }
}


class Other
{
    Dictionary<string, MyObject> MyObjectCollection { get; set; }

   private void function()
    {
        MyObjectCollection = new Dictionary<string, MyObject>()
            { { "key", new MyObject { NameA = "something", NameB = "something else" } } };                
        var valueA = MyObjectCollection["key"].NameA; // = "something"
    }
}

Is there a better way?

you can have a dictionary with key and a List of values `Dictionary> MyObjectCollection { get; set; }` — Renuka Deshmukh, Mar 22 '16 at 08:24

score 4 · Accepted Answer · answered Mar 22 '16 at 08:34

The solution which is easiest to implement (Dictionary<String, Tuple<String, String>>) is not the one which is easiest to support and develop (what is MyObjectCollection[key].Value2?). So I suggest using your own class:

  class MyPair {
    public string NameA { get; internal set; }
    public string NameB { get; internal set; }

    public MyPair(nameA, nameB) {
      NameA = nameA;
      NameB = nameB;  
    }

    public override String ToString() {
      return $"NameA = {NameA}; NameB = {NameB}";
    }
  }

  class Other {
    // you don't want "set" here
    // = new ... <- C# 6.0 feature
    public Dictionary<string, MyPair> Data { get; } = new Dictionary<string, MyPair>() {
      {"key", new MyPair("something", "something else")},
    };

   ...

 Other myOther = new Other();

 String test = myOther.Data["key"].NameA;

Thanks, accepted your answer. – Ory Zaidenvorm Mar 22 '16 at 08:47 — Ory Zaidenvorm, Mar 22 '16 at 08:47

score 2 · Answer 2 · answered Mar 22 '16 at 08:24

2

You can use a Tuple:

Dictionary<string,Tuple<string,string>> MyObjectCollection {get; set;}

private void function()
{
    MyObjectCollection = new Dictionary<string, Tuple<string,string>>();
    MyObjectCollection.Add("key1", Tuple.Create("test1", "test2"));               
}

answered Mar 22 '16 at 08:24

Alexander Derck

13,818
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Are there any benefits vs. using a custom class aside from the few lines of code saved? – Ory Zaidenvorm Mar 22 '16 at 08:38
1

@OryZaidenvorm Not really, I only use them internally because they're easier than defining a struct/class for everything. I wouldn't recommend exposing a Tuple as end result – Alexander Derck Mar 22 '16 at 08:41

score 0 · Answer 3 · answered Mar 22 '16 at 08:28

0

List<MyObject> list = new List<MyObject>();
var res = list.ToDictionary(x => x, x => string.Format("Val: {0}", x));

The first lambda lets you pick the key, the second one picks the value.

answered Mar 22 '16 at 08:28

Eminem

7,206
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C# - how to write a collection (Dictionary?) with one key and two values

3 Answers3