Encoding StringBuilder querystring

Question

I have some sample code where I want to build a query string but at the end of the code, the string is not encoded properly to be used in a browser.

public partial class UrlBuilder : System.Web.UI.UserControl
    {
        public string Title { get; set; }
        public string Url { get; set; }
        public bool EnableQryString { get; set; }

        public string QueryString1 { get; set; }
        public string QueryString2 { get; set; }
        public string QueryString3 { get; set; }
        public string QueryString4 { get; set; }
        public string QueryString5 { get; set; }

        protected void Page_Load(object sender, EventArgs e)
        {
            lnkUrl.Text = Title;
            lnkUrl.NavigateUrl = Url;

            if (EnableQryString)
            {
                StringBuilder SB = new StringBuilder();
                SB.AppendLine("?");

                #region Query String builder
                if (!QueryString1.IsNullOrEmpty())
                {
                    SB.AppendLine(QueryString1);
                }

                if (!QueryString2.IsNullOrEmpty())
                {
                    SB.AppendLine("&" + QueryString2);
                }

                if (!QueryString3.IsNullOrEmpty())
                {
                     SB.AppendLine("&" + QueryString3);
                }

                if (!QueryString4.IsNullOrEmpty())
                {
                     SB.AppendLine("&" + QueryString4);
                }

                if (!QueryString5.IsNullOrEmpty())
                {
                    SB.AppendLine("&" + QueryString5);
                }

                #endregion
                lnkUrl.NavigateUrl += HttpUtility.UrlEncode(SB.ToString());
            }
        }
    }

This is the string after:

HttpUtility.UrlEncode(SB.ToString());

http://www.google.com%3f%0d%0aA%3d1%0d%0a%26B%3d2%0d%0a

I think I am not using UrlEncode properly. Can someone help?

Thank you!

@Thewads I am expecting a standard url e.g. www.google.co.uk but if the boolean is true I have logic for changing the string. I expect www.google.co.uk?A=1&B=2 — nick gowdy
– nick gowdy, Commented Apr 25, 2014 at 15:26

Thewads · Accepted Answer · 2014-04-25 15:37:40Z

2

You are using AppendLine, which is adding in carriage returns (new lines) to your string, this can be seen with the %0d in your url string.

Simply change your logic to use the string builder Append method.

Example would be:

if (!QueryString1.IsNullOrEmpty())
{
    SB.Append(QueryString1);
}

edit: or if you want to encode only the parameters.

if (!QueryString1.IsNullOrEmpty())
{
    SB.Append(HttpUtility.UrlEncode(QueryString1));
}

I think it can be done either way, the docs at http://msdn.microsoft.com/en-us/library/h10z5byc.aspx say it can be used to encode the entire URL

edited Apr 25, 2014 at 15:37

answered Apr 25, 2014 at 15:30

Thewads

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2 Comments

nick gowdy Over a year ago

Hey, I have a problem with assigning my URL to lnkUrl, that is when the string has the carriage returns. I will update my code.

nick gowdy Over a year ago

Once debugging was done and I hovered over the URL it was correct. Thanks for your help.

LB2 · Accepted Answer · 2014-04-25 15:33:13Z

1

You should be calling HttpUtility.UrlEncode() on each individual value of the query string, rather than on the whole string. So something like

SB.Append("&name=" + HttpUtility.UrlEncode(value));

answered Apr 25, 2014 at 15:33

LB2

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Comments

Gusman · Accepted Answer · 2014-04-25 15:32:40Z

0

You are encoding all the url, you should only encode the parameters values, so as you have coded it, you must encode those values before you set in QueryStringX and don't encode anything else.

Or a better approach, do it in your QueryStringX, when set is called, split th value by "=", encode the second part of the result, join them in one string and store it for later use.

answered Apr 25, 2014 at 15:32

Gusman

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