How to get nested key value pair from dictionary with linq

Question

I have a lstSubs List<KeyValuePair<string, string> which contain value

FNAME, "ABC"
LNAME ,"XYZ"
VAR001, "VAR002"
VAR002 , "ActualValueforVAR001"
VAR003, "VAR004"
VAR004 , "VAR005"
VAR005, "ActualValueforVAR003"

I have a String like envelop "Hello [FNAME] [LNAME] you have created a request for [VAR001] which got assigned to [VAR003]"

 var regex = new Regex(@"\[(.*?)\]");
                    var matches = regex.Matches(envelop.ToString());
                    foreach (Match match in matches) 
                    {  
                       columnValue = linq to get the value from the list based on key;
                       envelop.Replace(match.Value, columnValue);
                    }

in this, The straight Key,Value pairs are easy to get via Linq but I am getting tough time to fetch the complex values which are nested in terms of connected Key, Value.

is there any way in LINQ or have to go with a loop. Expected Output : Hello ABC XYZ you have created a request for ActualValueforVAR001 which got assigned to ActualValueforVAR003

Thanks, PS. The code is not complete. it's a part of entire code edited with an intention to make it concise to issue

Edited: some of my text was not visible due to formatting. They Dictionary values are nested as I am creating them based on some conditions in which they got configured

VAR001 points to VAR002, so do you expect the when string is replaced, VAR001 should replace with actual value of VAR002 and VAR003 should replace with actual value of VAR005? — user1672994, Oct 11 '19 at 08:47

Dmitry Bychenko · Accepted Answer · 2019-10-11T10:26:50.430

First, let's turn initial List<T> into a Dictionary<K, V>:

  List<KeyValuePair<string, string>> list = new List<KeyValuePair<string, string>>() {
    new KeyValuePair<string, string>("FNAME", "ABC"),
    new KeyValuePair<string, string>("LNAME", "XYZ"),
    new KeyValuePair<string, string>("VAR001", "VAR002"),
    new KeyValuePair<string, string>("VAR002", "ActualValueforVAR001"),
    new KeyValuePair<string, string>("VAR003", "VAR004"),
    new KeyValuePair<string, string>("VAR004", "VAR005"),
    new KeyValuePair<string, string>("VAR005", "ActualValueforVAR003"),
  };

  Dictionary<string, string> dict = list.ToDictionary(
    pair => pair.Key, 
    pair => pair.Value,
    StringComparer.OrdinalIgnoreCase); // Comment out if should be case sensitive

  // Some values can be nested
  while (true) {
    bool nestedFound = false;

    foreach (var pair in dict.ToList()) {
      if (dict.TryGetValue(pair.Value, out var newValue)) {
        dict[pair.Key] = newValue;
        nestedFound = true;
      }
    }

    if (!nestedFound)
      break;
  }

Then for a given envelop

  string envelop = 
    @"Hello [FNAME] [LNAME] you have created a request for [VAR001] which got assigned to [VAR003]";

you can put a simple Regex.Replace:

  string result = Regex
    .Replace(envelop,
           @"\[[A-Za-z0-9]+\]",
             m => dict.TryGetValue(m.Value.Trim('[', ']'), out var value) ? value : "???");

  Console.Write(result);

Outcome:

  Hello ABC XYZ you have created a request for ActualValueforVAR001 which got assigned to ActualValueforVAR003

sorry for the trouble. but I think I wasn't able to put that up clearly. I need to traverse to find the ActualValue via keys.Thanks — Amit Singh, Oct 11 '19 at 09:23
@Amit Singh: I see; you have *nested* values; need some loop after initial dictionary creation; I've edited the answer — Dmitry Bychenko, Oct 11 '19 at 10:12
awesome, I actually did something the same, but your code is very clean. would be using this. Thanks for the help :) — Amit Singh, Oct 11 '19 at 10:25

How to get nested key value pair from dictionary with linq

1 Answers1