How to Add, Update, Save and Delete Key List> in C#

Question

Specific Problem I want to update KeyValue Pair, if I delete something , it should get deleted and remaining items gets saved, but when I delete a key, every value gets deleted. I just want to delete a specific value and retain the remaining values and save it back.

Edited: Obviously if I delete a key every value will get deleted, I want to delete a specific value from the key and retain remaining values from key.

Note: if my question is wrong you can suggest edits.

A Little Background:

1st ComboBox has category A and 2nd comboBox has category B. when I select category A, I generate some serials and at the same time I add to comboBox2 for display and add to keyvalue pair.

same with category B.

when I select category A, I only want to see generated serials in category A and when I select category B, I only want to see generated serials in category B.

This is why I'm using KeyValuePair, i could not find any other better solution, I save the file with json and when I load the application I reload the file and repopulate my comboBoxes with the data.

now I want to use a specific serial, when the serial is used, I want to remove it from the comboBox and also remove from the keyvalue pair and save back existing data.

here is the picture to understand it better.

Global Variables:

    List<KeyValuePair<int, string>> vals = new List<KeyValuePair<int, string>>();
    int from;
    int to;
    int result;

Following is the code to add List.

Add to comboBox and add to keyvalue pair.

 for (int i = 0; i <= result; i++)
     {
       string item = Convert.ToString(from + i);
       comboBox1.Items.Add(item);
       vals.Add(new KeyValuePair<int, string>(0, item));
     }

Save Code:

  string json = JsonConvert.SerializeObject(vals);
        using (StreamWriter sw = File.CreateText("C:\\Dictionary.txt"))
        {
            sw.Write(json);
        }

Repopulating comboBox

string jsonToRead = File.ReadAllText("c:\\Dictionary.txt");

        List<KeyValuePair<int, string>> myDictionaryReconstructed = 
            JsonConvert.DeserializeObject<List<KeyValuePair<int, string>>>(jsonToRead);

        if (comboBox1.SelectedIndex == 0)
        {
            comboBox2.Items.Clear();
            foreach (var item in myDictionaryReconstructed)
            {
                if (item.Key == 0) //If Key value is 0, if it is CategoryA
                {
                    comboBox2.Items.Add(item.Value);
                    comboBox2.Refresh();
                }
            }

How to Delete Key & Save back remaining data

// this is probably wrong way of doing it. // I want to delete that value that is selected in comboBox2

   private void DeleteButton_Click(object sender, EventArgs e)
    {
   // Deserialise it from Disk back to a Dictionary
        string jsonToRead = File.ReadAllText("c:\\Dictionary.txt");

        List<KeyValuePair<int, string>> myDictionaryReconstructed =
            JsonConvert.DeserializeObject<List<KeyValuePair<int, string>>>(jsonToRead);

        foreach (var item in myDictionaryReconstructed)
        {
            if (item.Key == 0) //If Key value is 0, if it is CategoryA
            {
                if (item.Value == this.comboBox1.SelectedValue.ToString())
                {
                    vals.Remove(new KeyValuePair<int, string>(0, comboBox1.SelectedValue.ToString()));
                }
            }

        }

        string json = JsonConvert.SerializeObject(myDictionaryReconstructed);
        using (StreamWriter sw = File.CreateText("C:\\Dictionary.txt"))
        {
            sw.Write(json);
        }


    }

`vals.Add(new KeyValuePair(0, item));` You always set the key pair as (0, something)? — Raskayu, Aug 05 '16 at 07:20
For category A I'm using 0 and for category B I'm using 1. `vals.Remove(new KeyValuePair(0, comboBox2.SelectedItem.ToString()));` using this deletes entire key, instead of just value. — Patrick, Aug 05 '16 at 07:36
Try using `IndexOf()` to get where the element is and `RemoveAt()` of vals, so you force deleting just one for sure — Raskayu, Aug 05 '16 at 08:59
Remove actually works fine. I think it's something related with the foreach loop which seemed rather unnecessary to me. @Patrick Have you actually debugged the behavior? Could you please try removing foreach block in `DeleteButton_Click` event and replace it with `vals.Remove(new KeyValuePair(0, comboBox1.SelectedItem.ToString()));` ? — uTeisT, Aug 05 '16 at 09:12
@uteist I removed for-loop and it worked, only comboBox did not get updated il check that... — Patrick, Aug 05 '16 at 10:34
I set comboBox2.SelectedIndex = -1, after removing value and it worked. Thanks uteist. — Patrick, Aug 05 '16 at 10:42
@Patrick I just posted it as an answer. Could u please mark it, if it helped? Ty — uTeisT, Aug 05 '16 at 11:05

score 1 · Accepted Answer · answered Aug 05 '16 at 11:04

I think it's something related with the foreach loop which seemed rather unnecessary to me.

Could you please try removing foreach block in

DeleteButton_Click

event and replace it with

vals.Remove(new KeyValuePair<int, string>(0, comboBox1.SelectedItem.ToString()));

How to Add, Update, Save and Delete Key List> in C#

1 Answers1