Consuming HTTP Services in Python Transcripts
Chapter: Screen scraping: Adding APIs where there are none
Lecture: Controlling your user agent in requests

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0:00 Here is a website we can use, called whatsmyuseragent.com
0:04 to actually check what it thinks and pretty much any other web server in the world
0:08 is going to think we are when we talk to it.
0:11 So if we pull that up in Firefox, let me do a request to it,
0:15 you can see it will say what is your user agent,
0:17 your user agent is something like this, Mozilla 5,
0:21 running on Macintosh, Intel running OS 10 Sierra and this version, 51 on Firefox,
0:26 and here, isn't this cool, I even have a public ipv6 address these days
0:31 I'm feeling so much like I'm in the future, okay so if we do a request,
0:34 against that url, it's going to redirect it here, and it turns out
0:38 that there is a special tag or id on that little section of where it says
0:44 what our user agent is, so they can style it, hm, I wonder if we could get that back.
0:48 So over here, what we're going to do is we're going to do a request,
0:51 and we're going to do a get, and we're going to use Beautiful Soup,
0:54 and this time instead of using lxml just to show you you could do the other one,
0:58 we'll use the built in parser, and then we want to go
1:02 grab that user agent and get its text, and print it out,
1:06 so we could do that, and our reported user agent is no surprise,
1:10 Python-request 213. In fact, I think we could do this
1:14 as a select one and drop this zero, get the same effect.
1:20 Perfect, that's more like it. Okay, so how do we control this,
1:23 well, it's this step where we control
1:26 what gets sent to the server, so we can do this with headers,
1:30 because the user agent is just a header, so this is going to be a dictionary,
1:33 and the value is going to be user- agent and then what we put in here is
1:38 whatever we want, you want it to think we're exactly what we were with Firefox,
1:41 fine, oh, there might be a small problem, if you don't pass it along.
1:46 Want to be like Firefox, boom we are, we could even have fun with them,
1:50 so you know, we're Mozilla 7, we're OS 10 32 and we're even Firefox 54,
1:57 just to show you like we can put whatever we want here, alright,
2:00 maybe they think some super secret version of Mac OS is like being prototype
2:06 down their site, who knows, but see,
2:08 we're running Firefox 54, never mind the newest one is 51,
2:11 we can tell it this and it gets sent right along, so there is a couple of uses for this,
2:15 like I said, it could be that you might want to specifically get the desktop site
2:19 or the mobile site and you can control whether you look mobile
2:23 or you look desktopy by setting your user agent,
2:26 you might also be getting blocked if you look like some kind of robot
2:30 so you can look non robot like by doing this, yeah, there is a couple of reasons,
2:33 you also might want to set it to be your own custom thing,
2:37 so we don't want to do this, I'll save this for you,
2:39 but maybe we want something else with user agent,
2:42 maybe we want to say I am super user agent 007 version 0.1, right,
2:50 maybe you want to pass information say this is actually this application
2:53 and it's this version that we're working with
2:56 so there might be a reason you want to pass that as well,
2:59 so we could be sure user agent 007 version .1, whatever you want, right,
3:02 there is a couple of reasons and the value you choose might depend on your thinking.
3:07 But, it can be important to control your user agent
3:10 because it determines the html that you get.