ASP.Net MVC : Get query values with no key

Question

I have URL: http://site.com/page.aspx?update

how do I check if that update value is present?

HttpValueCollection treats that as an entity with null key. I have tried:

var noKeyValues = Request.QueryString.GetValues(null);
if (noKeyValues != null && noKeyValues.Any(v=>v==update)) ...

but it gives me a frowny line, because GetValues' argument is decorated with [NotNull].

so I end up doing:

    var queryValuesWithNoKey =
            Request.QueryString.AllKeys.Select((key, index) => new { key, value = Request.QueryString.GetValues(index) }).Where(
                    item => item.key == null).Select(item => item.value).SingleOrDefault();
    if (queryValuesWithNoKey != null && queryValuesWithNoKey.Any(v => v.ToLower() == "update")) live = true;

not the most elegant workaround. Is there a better way to get key-less value from query string?

Mike Chamberlain · Accepted Answer · 2015-07-08 14:37:51Z

5

You can use

Request.QueryString[null]

to retrieve a comma separated list of keys with no values. For instance, if your url is:

http://mysite/?first&second

then the above will return

first,second

In your case, you could just do something like:

if(Request.QueryString[null] == "update") 
{
    // it's an update
}

edited Jul 8, 2015 at 14:37

answered Nov 16, 2012 at 5:50

Mike Chamberlain

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2 Comments

THX-1138 Over a year ago

I stil get warning argument decorated with [NotNull] if I don't mind that - I can as well use Request.QeryString.GetValues(null). I wonder if warning is baseless, since I don't see [NotNull] on the argument.

Mike Chamberlain Over a year ago

Yeah I think the same thing. It all seems to work OK, so I'm not worrying too much about the warning.

BlackTigerX · Accepted Answer · 2011-04-13 18:29:28Z

1

if that's the only key you would use

Request.QueryString.ToString() to get the "update" value

answered Apr 13, 2011 at 18:29

BlackTigerX

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Comments

A.R. · Accepted Answer · 2018-07-10 14:38:48Z

0

I know I'm late to the party, but this a function that I use for this kind of task.

internal static bool HasQueryStringKey(HttpRequestBase request, string key)
{
    // If there isn't a value, ASP will not recognize variable / key names.
    string[] qsParts = request.QueryString.ToString().Split('&');
    int qsLen = qsParts.Length;
    for (int i = 0; i < qsLen; i++)
    {
        string[] bits = qsParts[i].Split('=');
        if (bits[0].Equals(key, StringComparison.OrdinalIgnoreCase))
        {
            return true;
        }
    }

    return false;
}

You may need to update it so that it is case sensitive, or uses different arguments depending on your purposes, but this has always worked well for me.

answered Jul 10, 2018 at 14:38

A.R.

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1 Comment

aloisdg Over a year ago

I cannot speak for the proc/cons of this solution, but here a one liner of it

return request.QueryString.ToString().Split('&').Select(parts => parts.Split('=')).Any(bits => bits[0].Equals(key, StringComparison.OrdinalIgnoreCase));

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