Available inall subroutines.

Returns the given URL with the given parameter name set to the given value, replacing the original value and removing any duplicates. If the parameter is not present in the query string, the parameter will be appended with the given value to the end of the query string. The parameter name and value will be URL-encoded when set in the query string.


set req.url = querystring.set(req.url, "foo", "baz");

Try it out

querystring.set is used in the following code examples. Examples apply VCL to real-world use cases and can be deployed as they are, or adapted for your own service. See the full list of code examples for more inspiration.

Click RUN on a sample below to provision a Fastly service, execute the code on Fastly, and see how the function behaves.

Normalize requests to increase cache efficiency

Improve cache performance by normalizing requests. Filter and reorder query params, convert to lowercase, filter headers, and more.