har-export-trigger | Trigger HAR export any time directly from within a page | HTTP library

I want to be able to get a body of the specific subrequest using a selenium behind the proxy.

Now I'm using python + selenium + chromedriver. With logging I'm able to get each subrequest's headers but not body. My logging settings:

caps['loggingPrefs'] = {'performance': 'ALL', 'browser': 'ALL'}

caps['perfLoggingPrefs'] = {"enableNetwork": True, "enablePage": True, "enableTimeline": True}

I know there are several options to form a HAR with selenium:

• Use geckodriver and har-export-trigger. I tried to make it work with the following code:

window.foo = HAR.triggerExport().then(harLog => { return(harLog); }); return window.foo;

Unfortunately, I don't see the body of the response in the returning data.

• Use browsermob proxy. The solution seems totally fine but I didn't find the way to make browsermob proxy work behind the proxy.

So the question is: how can I get the body of the specific network response on the request made during the downloading of the webpage with selenium AND use proxies.

UPD: Actually, with har-export-trigger I get the response bodies, but not all of them: the response body I need is in json, it's MIME type is 'text/html; charset=utf-8' and it is missing from the HAR file I generate, so the solution is still missing.

UPD2: After further investigation, I realized that a response body is missing even on my desktop firefox when the har-export-trigger add-on is turned on, so this solution may be a dead-end (issue on Github)

UPD3: This bug can be seen only with the latest version of har-export-trigger. With version 0.6.0. everything works just fine.

So, for future googlers: you may use har-export-trigger v. 0.6.0. or the approach from the accepted answer.