[chaley]

Originally Posted by isarl

(At first I thought the Calibre template function to_hex() might be useful, but it hex-encodes the entire string, and without the “%” character. Not really what we want here.)

Actually, to_hex() is exactly what you want. If you use it then you don't do any url encoding.

Libraries that are hex encoded must start with '_hex_-'.

Here is an example of building a calibre:// url using the function.

program:
	lib = 'library.test_small';
	hex_lib = '_hex_-' & to_hex(lib);
	url = 'calibre://book-details/' & hex_lib & '/' & $id;
	'<a href="' & url & '">Book id ' & $id & '</a>'

It produces links that look like

calibre://book-details/_hex_-6c6962726172792e746573745f736d616c6c/1385

You can also use it for query strings. Instead of q=string, you use eq=hex-encoded-string.

All of this is documented here.