I want to pass res_partner_ids in the URL to the calendar view, so that when a user selects a time slot, a popover opens with the selected partners pre-filled.
For example, if I go to:
http://localhost:8069/odoo/calendar?res_partner_ids=5,6,7
I'm redirected to the default URL: http://localhost:8069/odoo/calendar
Then, when I'm on the http://localhost:8069/odoo/calendar page and open the calendar event popover when I select a time, I want it to automatically include the partners from res_partner_ids in the list of attendees.
This is not how actions in Odoo work. There is no implementation of GET parameters in this way. Where do you want to have such a link added in the first place?
As an example: See any Activity (in Chatter) -> Meeting: You will be redirect to /odoo/calendar and upon clicking a time slot, for example the name of the meeting to be created reflects the record this meeting is create for. This whole functionality is based on the context based on by the action actually triggering the rendering of the view.
*based on the context passed on