How to build a query string for a URL in C#?

Question

A common task when calling web resources from a code is building a query string to including all the necessary parameters. While by all means no rocket science, there are so

Answer 1

Add this class to your project

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

public class QueryStringBuilder
{
    private readonly List> _list;

    public QueryStringBuilder()
    {
        _list = new List>();
    }

    public void Add(string name, object value)
    {
        _list.Add(new KeyValuePair(name, value));
    }

    public override string ToString()
    {
        return String.Join("&", _list.Select(kvp => String.Concat(Uri.EscapeDataString(kvp.Key), "=", Uri.EscapeDataString(kvp.Value.ToString()))));
    }
}

And use it like this:

var actual = new QueryStringBuilder {
    {"foo", 123},
    {"bar", "val31"},
    {"bar", "val32"}
};

actual.Add("a+b", "c+d");

actual.ToString(); // "foo=123&bar=val31&bar=val32&a%2bb=c%2bd"