C# how to search in Dictionary key by array of tags

Question

I am learning c# and I am trying something simple: inputing some tags separated by comma the code to return a message. The idea is that the code should filter by all the tags that I am splitting into an array.

Defining the variables:

Dictionary<string[], string> messages = new Dictionary<string[], string>();
messages.Add(new string[] { "greeting", "hello", "hei", "hi" }, "Hello!");
messages.Add(new string[] { "greeting", "bye", "buh-bye", "sayonara" }, "Bye!");

Getting the tag:

string[] tags;
tags.Add("greeting");
tags.Add("hello");

The list and iterating:

List<string> lista = new List<string>();
foreach(string tag in e.GetArg("Tag").Split(','))
{
    foreach (KeyValuePair<string[], string> entry in gifs)
    {
        if (entry.Key.Contains(tag))
        {
            lista.Add(entry.Value);
        }
    }
}

The problem with this is that it adds every met item for each tag in the list, even the bye item. Can I filter this with an array of tags? Or I need to pass it more times, each time getting the desired one(s)?

Answer 1

I think you may use simple class for searching by tags. This solution will improve abstraction level of your code. Class example:

public class TagDictionary
{
    Dictionary<string, HashSet<string>> _innerStorage = new Dictionary<string, HashSet<string>>();

    public void Add(IEnumerable<string> tags, string value)
    {
        foreach (var tag in tags)
        {
            if (_innerStorage.ContainsKey(tag))
            {
                var hash = _innerStorage[tag];
                if (!hash.Contains(value))
                {
                    hash.Add(value);
                }
            }
            else
            {
                _innerStorage[tag] = new HashSet<string>
                {
                    value
                };
            }
        }
    }

    public HashSet<string> GetValuesByTags(IEnumerable<string> tags)
    {
        var result = new HashSet<string>();
        foreach (var tag in tags)
        {
            if (_innerStorage.ContainsKey(tag))
            {
                result.UnionWith(_innerStorage[tag]);
            }
        }
        return result;
    }
}

Use example:

    static void Main(string[] args)
    {
        var messages = new TagDictionary();
        messages.Add(new string[] { "greeting", "hello", "hei", "hi" }, "Hello!");
        messages.Add(new string[] { "greeting", "bye", "buh-bye", "sayonara" }, "Bye!");

        foreach (var value in messages.GetValuesByTags(new[] { "greeting", "hello" }))
        {
            Console.WriteLine(value);
        }
    }

Just string[] is not good key type for standard Dictionary.

Answer 2

Search Dictionary by key array

        Dictionary<string[], string> messages = new Dictionary<string[], string>();
        messages.Add(new string[] { "greeting", "hello", "hei", "hi" }, "Hello!");
        messages.Add(new string[] { "greeting", "bye", "buh-bye", "sayonara" }, "Bye!");

        // add tags
        string[] tags = new string[2];
        tags[0] = "greeting";
        tags[1] = "buh-bye";

        List<string> lista = new List<string>(); // list to store the results

        // loop true the keys from every row
        // loop true the keys of the current row
        // check if tags contains key 
        // ckeck if lista already contains the key that was recognized(no duplicates in list)

        foreach (var value in messages.Keys)
            foreach (var value1 in value)
                if (tags.Contains(value1))
                    if(!lista.Contains(messages[value]))
                        lista.Add(messages[value]);

Output

      ==========
      lista Count = 2
      1: Hello
      2: Bye!