Adding items to C# dictionary from JavaScript

Question

What, if any, is the accepted way of adding a key-value pair from ASP.NET/JavaScript code to a C# dictionary? TIA.

What is the persistence of the C# dictionary? As both bits of code are executed at separate times, the persistence of the dictionary will need to be greater than that of simply the page life-cycle. — Richard
– Richard, Commented Jun 27, 2012 at 23:32
I have tried using post-backs but I seem to lack the knowledge for implementing several independent post-back loops (since I am already having a post-back event that processes some other data). I know C# reasonably well but I'm new to using it together with ASP/JS. — Arets Paeglis
– Arets Paeglis, Commented Jun 27, 2012 at 23:46

Jo-Pierre · Accepted Answer · 2012-06-28 00:25:47Z

1

How I've handled this requirement is to get all the data in a name value pair in javascript, then post this to the server via ajax ...

e.g. loc is your page, methodName being the WebMethod in code behind page, arguments you can populate as

var arguments = '"data":"name1=value1&name2=value2"';

$.ajax({
    type: "POST",
    url: loc + "/" + methodName,
    data: "{" + arguments + "}",
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: onSuccess,
    fail: onFail
});

On your code behind, create a web method e.g

[System.Web.Services.WebMethod(EnableSession = true)]
public static string ItemsForDictionary(string data)
{
    Dictionary<String, String> newDict = ConvertDataToDictionary(data);
}

I use a generic method to convert this data parameter in codebehind to a Dictionary.

private static System.Collections.Generic.Dictionary<String, String> ConvertDataToDictionary(string data)
    {

        char amp = '&';
        string[] nameValuePairs = data.Split(amp);

        System.Collections.Generic.Dictionary<String, String> dict = new System.Collections.Generic.Dictionary<string, string>();

        char eq = '=';

        for (int x = 0; x < nameValuePairs.Length; x++)
        {
            string[] tmp = nameValuePairs[x].Split(eq);
            dict.Add(tmp[0], HttpUtility.UrlDecode(tmp[1]));

        }

        return dict;
    }

Anyways .. hope this gives you the idea ...

answered Jun 28, 2012 at 0:25

Jo-Pierre

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Arets Paeglis Over a year ago

Thanks. Apparently I didn't correctly evaluate how much mess should I anticipate from this task.

Andrew Cooper · Accepted Answer · 2012-06-27 23:33:19Z

0

You can't do it directly. You'd have to send the data back to the server using a post-back or ajax call, and then add the data to the Dictionary in the server-side handler.

We could probably be more helpful if you post some of your code to show what you're actually trying to do.

answered Jun 27, 2012 at 23:33

Andrew Cooper

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Arets Paeglis Over a year ago

The current code is a bit too much of a spaghetti mess to post but the idea is as follows. Given: A C# class that generates and renders a customised HTML table, in which each row contains, among others, a cell with a button in it; each cell and each row has an assigned ID. Task: Write an OnClick event for the button that, when triggered, generates a certain number, takes it together with the row's ID (i.e. fetches it from C# side) and stores the resulting pair off in a persistent C# dictionary for later lookup.

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