Add a referer header when new issues are created and redirected to issue page

[miketaylr]

See #1273 (comment)

We can use that as a signal to show the "Thanks!" flash message, rather than the current (hacky, imo) solution of using session.

See https://github.com/webcompat/webcompat.com/blob/master/webcompat/views.py#L214 and all other instances of session['show_thanks'] = True

[nj4710]

Hi @miketaylr I would like to work on this

[miketaylr]

Cool! We might want to get @karlcow to review these patches when they're ready.

[karlcow]

I will remove the status: good next bug for now. As I think it requires a bit more knowledge. Let's rewind a bit and give a longer description of the issue.

Some background.

An HTTP POST is not idempotent and not safe. It means that two subsequent POST /issues/new do not create the same results. In our case each of them will create a new issue and create a new URI. So when we do a POST the server is replying to us and provide a number. We want to use this number to redirect the browser to the URL of the issue and at the same time show a flash message.

In #1273, @miketaylr implemented a way to

1. redirect the browser to the issue which has just been created aka through POST /issues/new.
2. And show the Thanks message.

He is doing the Thanks message by storing in session a keyword with the value True.

session['show_thanks'] = True
return redirect(url_for('show_issue', number=response.get('number')))

This is then used in @app.route('/issues/<int:number>') with def show_issue(number): where it is checked if session contains the right keyword to send the show_thanks and then removes it from the session. This function/route is used for showing issues. So we do not want to send the thanks message all the time. That's why there is the current session mechanism.

webcompat.com/webcompat/views.py

Lines 208 to 217 in 5fdbb0d

	@app.route('/issues/<int:number>')
	@cache_policy(private=True, uri_max_age=0, must_revalidate=True)
	def show_issue(number):
	'''Route to display a single issue.'''
	if g.user:
	get_user_info()
	if session.get('show_thanks'):
	flash(number, 'thanks')
	session.pop('show_thanks')
	return render_template('issue.html', number=number)

What I suggested in my comment is that instead of storing a session for this flash message. We just use the fact that we show the flask message only when we come from POST /issues/new. It means when accessing /issues/<int:number> we need to check the HTTP Referer on the request. If it comes from /issues/new then we send a show thanks message. So instead of a if session.get()… we would use a if request.referer

Things to do:

• Create tests to make sure that the referer is here when we transition from POST /issues/new to GET /issues/issue_number Probably in test_urls.py
• Change the show_issue to use the referer
• Clean the code elsewhere that we are sure we don't use the two ways of doing things
• Make sure that we don't break the functional tests
• Run nosetests

[nj4710]

That was a great explanation. Thank you so much.
Sorry for my last commit.
Can I at-least try and complete one of these tasks?
So, what I understand from this is we do not need to use set_referer or get_referer method in def create_issue(). We will need to remove the session variables from this function since we are not using them anymore.

Now, inside show_issue(number) we need to change the if condition, since we are checking the referer now. It will be if request.referrer == ('/issues/new') and then show the flask message.

Please correct me if I am wrong.
Also, am I eligible to work on this? Since my last PR is in review.
Thanks

[karlcow]

@nj4710 You are always welcome to work on things. And if you can't finish for any reasons it is ok too. And we will help along the way or find a solution together. 🆒

[nj4710]

I tried to complete the show_issue task. r? @karlcow

[miketaylr]

I tried to complete the show_issue task. r? @karlcow

(Our process is to create a PR and ask for review in that, rather than a comment in a bug. :)) It's also OK to open up a PR and ask for feedback as you're developing things, before things are 100% ready for review.

[karlcow]

See my comments in @nj4710 Pull Request
#1466 (comment)

My initial idea was bad and that was discovered by exploring the pull request of @nj4710
For the record, @nj4710 did a good work.

I'm closing the issue as wontfix. Thanks.