Is it possible to implement this functionality even if the user is not logged in? If I collect email addresses through the survey, is there a method to match these emails with the corresponding contacts? Thanks in advance!

Answer above only covers use cases when survey is related to a user.

But in real life you want to relate survey results to products, affiliates, partners, ... 

In my case I have service tasks to assess partners, doing a supplier audit/assessment.

So you have somehow relate the survey to a particular partner and their products, which is not supported out of the box.

The approach I've implemented in odoo is outlined as follows

• Inherit Controller to write related business object info)
  
• In calling the  survey (URL-Action) pass the context (related business object info)
• Inherited Controller process the context and add it to survey.user_input

Custom Controller

Important here: add an additional parameter, in my case task_id

The clue is to pass your context info in the additional_vals which are then evaluated and written by default to the survey.user_input.

You have to inherit of course the according to your needs.

class SurveyController(Survey):        
	​@http.route('/survey/start/', type='http', auth='public', 	​website=True)    
   def survey_start(self, survey_token, answer_token=None, email=False, task_id=None,**post):
   	​	​# the clue, add additional_vals, which are then written to the survey anser        
	​ 	​additional_vals = {} # f
	​	​if task_id:            
	​	​	​reffering_task = request.env['project.task'].sudo().search([
	​	​	​	​('id', '=', task_id)], limit=1)            
	​	​	​additional_vals = {'my_partner_id': reffering_task.partner_id.id,
	​	​	​  'my_standard_id': reffering_task.standard_id.id                    # rest of the controller remain unchanged
	​....

Call Survey:

Survey is called by url action. you have to add your context info (in my case task_id) to be evaluated be the survey controller start (see above)

...

   self.ensure_one()        
	​url = '%s?%s' % (self.get_start_url(), werkzeug.urls.url_encode(
	​	​{'answer_token': answer and answer.access_token or None,
	​	​'task_id': self.id}))

 # open via URL-Action        
	​return {
	​	​'type': 'ir.actions.act_url',
		​​'name': "Start Survey", 
	​	​'target': 'new', 
	​	​'url': url        
	​}

Since the Customer is a Contact in Odoo (res.partner records) you can use Odoo Studio to create a smart button to access all responses, because the partner_id field is already on the Survey Response (if the Customer is logged in when they reply).

First, create a field on the Contact to link to the Survey Responses:

Next, use Odoo Studio to create the Smart Button:

Once you send a Survey and receive a response, you will see them from the Contact record.