Retrieve params value via substitution?

Advanced list filter accepts only sql query and substitutions.
Is it possible to retrieve a specific fields params value via substitution and use it in that query?

Something like [cb:userfield param="param name"]

That would be very handy.

Otherwise as the params field seems to contain JSON only other option seems to be SQL query using json_extract?

What I need is the values for year_min/max resp. age_min/max from a date field for filtering.

There are no plans to implement a substitution for outputting parameter values. Best way to access that information is a CB Code Field, load the field object, and parse its parameters for whatever value you're needing.

That's an interesting idea. I will check this out.

Unfortunately I don't have CB Code Field from when i was a professional member. So it seems there is no other solution than using MySQL Json extraction capabilities.
I believe it would be worth considering an easy built in way to read those params values for further processing or comparing.

We are not going to implement substitutions for parameters. It would be far too easy to cause a vulnerability with that. All it would take is user content going through substitutions and the user themselves could pull parameter values from your site. It's not going to happen, sorry.