How to extract parameters from a URL?

Observe can parse a URL into a JSON array, and then extract the elements of that array to get parameters. There is no parse_query_params function.

To parse the URL, use the following OPAL statement:

make_col parsedUrl:parse_url(url)

This will create a new column called parsedUrl that contains a JSON array of the URL parts.

You can then extract the parameters into their own JSON array, and filter out ones that are empty:

make_col parameters:parsedUrl.parameters
filter parameters != "null"

If you only want a specific parameter name, that can be done from the url object as well:

make_col key1:string(parsedUrl.parameters.key1),
    key2:string(parsedUrl.parameters.key2)