amp-analytics does not accept query string parameters with 2 _'s in them

[mborof]

What's the issue?

When using amp-analytics if I build a request that has a query string parameter with 2 _'s in it then amp-analytics does not generate any requests.

For example, this generates an HTTP post:

const VENDOR_CONFIG = jsonLiteral({
'requests': {
// Variables
'req' : 'https://pubads.g.doubleclick.net/subopt?',
},
triggers: {
on: {
'on': 'visible',
'request': 'req',
},
'transport': {
'beacon': true,
'xhrpost': false,
'image': false,
},
});

And this does not generate an HTTP post:

const VENDOR_CONFIG = jsonLiteral({
'requests': {
// Variables
'req': 'https://pubads.g.doubleclick.net/subopt?__amp_source_origin=${sourceHost}',
},
triggers: {
on: {
'on': 'visible',
'request': 'req',
},
'transport': {
'beacon': true,
'xhrpost': false,
'image': false,
},
});

How do we reproduce the issue?

1. Create a JavaScript file with the above in it inside the amp-analytics vendors folder.
2. Register the component in vendors.js (remember the TYPE)
3. Add this tag to an amp page (filling in the TYPE):
   

4. Execute the page you added it to. You should see a request generated without the __ query string param and not see one generated with it.

What browsers are affected?

I was specifically testing in Chrome; I did not test other browsers.

Which AMP version is affected?

This is the current version of AMP (as of 12/11/2019). I have no seen this work previously (or tried).

[micajuine-ho]

Hi @mborof, thank you for your issue report.

Are you still experiencing this issue?

I tried to reproduce this issue, through both inline config as well as altering a vendor config, without any success.

[mborof]

Yes. In this PR:

#26003

If I modify "subscriptions-propensity.json" so that _amp_source_origin= is instead __amp_source_origin I no longer get any amp-analytics HTTP requests from my propensity module.

[micajuine-ho]

@mborof Thanks for your follow up.

The reason for this is that __amp_source_origin is not allowed as a parameter name and not that it has 2 leading underscores. See #4670 for more details.

[mborof]

Makes sense. Closing.