How can I convert a NameValueCollection to a KeyValuePair

Question

I want to convert a NameValueCollection to a KeyValuePair. Is there a way to do this easily for just a single value in a NameValueCollection?

I have this right now but it seems kind of verbose:

private KeyValuePair<string, string> GetEtagHeader(NameValueCollection collection)
{
    var etagValue = collection.Get(HttpRequestHeader.IfMatch.ToString());

    return new KeyValuePair<string, string>(HttpRequestHeader.IfMatch.ToString(), etagValue);
}

Keep in mind that name value collection - like http headers allows single key with multiple values. — Ondrej Svejdar, Nov 20 '18 at 22:28

pamcevoy · Accepted Answer · 2018-11-29T01:08:44.263

I'm not sure how much shorter you can get it.

One possibility is to put the Get in where you create the KeyValuePair

private static KeyValuePair<string, string> GetEtagHeader(NameValueCollection collection)
{
    string key = HttpRequestHeader.IfMatch.ToString();
    return new KeyValuePair(key, collection.Get(key));
}

That should serve your case. I'd go a step further and split it into 2 methods - one for your specific case and one generic helper.

private static KeyValuePair<string, string> GetEtagHeader(NameValueCollection collection)
{
    return ToKeyValuePair(HttpRequestHeader.IfMatch.ToString(), collection);
}

private static KeyValuePair<string, string> ToKeyValuePair(string key, NameValueCollection collection)
{
    return new KeyValuePair(key, collection.Get(key));
}

These methods should be `static` since they don't reference any members of the enclosing class. Better yet, they could be extension methods with a `this NameValueCollection collection` parameter. — TypeIA, Nov 20 '18 at 22:44

score 0 · Answer 2 · answered Nov 20 '18 at 22:27

0

It would be less verbose if you put HttpRequestHeader.IfMatch.ToString() into a temp variable and instead inline the temp etagValue:

private KeyValuePair<string, string> GetEtagHeader(NameValueCollection collection)
{
    string key = HttpRequestHeader.IfMatch.ToString();
    return new KeyValuePair<string, string>(key, collection.Get(key));
}

answered Nov 20 '18 at 22:27

Olivier Jacot-Descombes

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The method should be `static` since it doesn't reference any members of the enclosing class. Better yet, it could be an extension method with a `this NameValueCollection collection` parameter. – TypeIA Nov 20 '18 at 22:44
Yes, unless `HttpRequestHeader` is an instance property. – Olivier Jacot-Descombes Nov 20 '18 at 22:48

score 0 · Answer 3 · answered Nov 21 '18 at 00:25

If it were me, I'd define an extension method like this one:

public static class ExtensionMethods
{
    static public KeyValuePair<string,string> GetPair(this NameValueCollection source, string key)
    {
        return new KeyValuePair<string, string>
        (
            key,
            source.Get(key)
        );
    }
}

Then you can just write your original code like this:

private KeyValuePair<string, string> GetEtagHeader(NameValueCollection collection)
{
    return collection.GetPair(HttpRequestHeader.IfMatch.ToString());
}

How can I convert a NameValueCollection to a KeyValuePair

3 Answers3