Flurl (Fluent Url) custom serialization - query-string

Question

How do I override Flurl's default behaviour when serializing objects to query string values? E.g. the below code
DateTime date = new DateTime(2017, 1, 2, 3, 4, 5);
Url url = "http://domain.com".SetQueryParam("date", date);
produces the following url:
http://domain.com?date=01%2F02%2F2017%2003%3A04%3A05
What I want is this:
http://domain.com?date=2017-01-02T03%3A04%3A05.0000000
which would be the result of serializing the date as follows:
date.ToString("O")

Answer 1

Flurl takes care of URL-encoding but beyond that isn't really concerned with custom string formatting. I guess the most obvious way to do what you want is this:
"http://domain.com".SetQueryParam("date", date.ToString("O"));
If you're doing this a lot and want to avoid specifying the formatting bit every time, you could add your own extension methods (one for Url and one for string, per the pattern):
public static Url SetDateParam(this Url url, string name, DateTime date)
{
return url.SetQueryParam(name, date.ToString("O"));
}
public static Url SetDateParam(this string url, string name, DateTime date)
{
return new Url(url).SetDateParam(name, date);
}
Then you've got:
"http://domain.com".SetDateParam("date", date);