1 00:00:05,320 --> 00:00:09,790 Welcome back, everyone, to this lecture where we're going to be discussing responses and for, of 2 00:00:09,790 --> 00:00:10,210 course. 3 00:00:11,280 --> 00:00:16,350 So inevitably, there's going to be a time when a client requests a Web page view that doesn't actually 4 00:00:16,350 --> 00:00:22,380 exist, or they accidentally provided the incorrect URL route that didn't match up with what you were 5 00:00:22,380 --> 00:00:24,060 expecting on your end of things. 6 00:00:24,420 --> 00:00:30,960 In these cases, you can try to preempt an error page by using a dispute response not found to still 7 00:00:30,960 --> 00:00:35,670 return some web page for the user and at least inform them that you weren't able to find what they were 8 00:00:35,670 --> 00:00:36,270 looking for. 9 00:00:37,540 --> 00:00:43,690 Django also has a default for a four page that we can display in case we get a 404 error. 10 00:00:44,140 --> 00:00:49,030 So later on, we're going to have a lot deeper into templates and see how to create our own custom 404 11 00:00:49,030 --> 00:00:49,390 page. 12 00:00:49,630 --> 00:00:54,550 But for right now, I'll just focus on two main functions, which is HTP response not found. 13 00:00:54,670 --> 00:00:57,310 And then the HDP 404 response. 14 00:00:57,610 --> 00:00:59,410 Let's head back to our code editor. 15 00:00:59,890 --> 00:01:00,130 All right. 16 00:01:00,160 --> 00:01:02,530 Here I am back at the website we've been working with. 17 00:01:02,890 --> 00:01:09,670 Recall that we had this dictionary of articles and then a news view that ended up showing you the particular 18 00:01:09,670 --> 00:01:12,280 page for whatever topic was asked for. 19 00:01:12,310 --> 00:01:14,410 And then we had this kind of silly ad view here. 20 00:01:14,710 --> 00:01:17,980 I'm going to collapse this one since we won't be working with it right now. 21 00:01:18,460 --> 00:01:23,710 And then here in URLs that pie, we ended up using that topic and displayed that particular news view 22 00:01:24,010 --> 00:01:25,870 from the articles dictionary. 23 00:01:26,170 --> 00:01:32,890 But right now, if we go to our website and say something like first app for sports, we get the sports 24 00:01:32,890 --> 00:01:33,310 page. 25 00:01:33,580 --> 00:01:38,410 But then if I ask for something that's not there like arts, then I get a key error. 26 00:01:38,800 --> 00:01:43,720 Well, it'd be nice if I could try to preempt this sort of error and just tell the user, Hey, I can't 27 00:01:43,720 --> 00:01:46,090 find anything for this particular topic. 28 00:01:46,270 --> 00:01:47,200 How do we actually do that? 29 00:01:47,650 --> 00:01:52,240 Well, we'll come back to our view and we're going to use a try except statement. 30 00:01:52,780 --> 00:01:56,320 So what we're going to do is we are going to inside of news view. 31 00:01:56,770 --> 00:02:01,360 We're first going to attempt to try make sure our indentations correct here. 32 00:02:01,780 --> 00:02:06,850 We're going to try to figure out that particular headline or page. 33 00:02:07,300 --> 00:02:09,789 So I can say result is equal to. 34 00:02:10,180 --> 00:02:13,420 And then I'm going to say here articles. 35 00:02:14,310 --> 00:02:15,180 Topic past. 36 00:02:15,420 --> 00:02:22,180 So I'm going to try to get that result and then we're going to return, and here we're going to grab 37 00:02:22,710 --> 00:02:26,490 your response article's topic, so we're going to try to do what we just did before. 38 00:02:26,760 --> 00:02:31,560 Now, in the case that we can't find something like arts, that's where we have to have some sort of 39 00:02:31,560 --> 00:02:35,370 exception where we can use the h to the poor response not found. 40 00:02:35,880 --> 00:02:40,830 So what I'm going to do then, is if that fails, I can say, except. 41 00:02:41,280 --> 00:02:47,130 And if the accept line or block is already running, then I know we don't have that topic. 42 00:02:47,640 --> 00:02:50,640 So I could just say result is equal to. 43 00:02:51,870 --> 00:02:53,280 Let's say no page. 44 00:02:54,250 --> 00:02:55,480 For that topic. 45 00:02:57,090 --> 00:03:04,380 And then inside of this block, I'm going to have and then sit here, return, and here I can say HTP 46 00:03:04,380 --> 00:03:05,020 response. 47 00:03:05,700 --> 00:03:07,680 And I say it should be a response. 48 00:03:08,710 --> 00:03:12,100 Not found, and in order to use this, you have to make sure to import it. 49 00:03:12,370 --> 00:03:16,690 So at the top here, I've already imported from response HTP response not found. 50 00:03:17,110 --> 00:03:20,920 This is essentially a further indication that, hey, what you're looking for, I don't actually have 51 00:03:20,920 --> 00:03:21,790 a web page for that. 52 00:03:22,120 --> 00:03:27,190 And then we can still pass in results here, and we're going to save that. 53 00:03:28,300 --> 00:03:32,020 And so now what happens is we come back here and I refresh this. 54 00:03:32,990 --> 00:03:39,770 I say, hey, no page for that topic, but what's nice about this is instead of just doing a normal 55 00:03:39,830 --> 00:03:45,650 HTP response, I'm actually taken to account of the fact that this is technically if we look down at 56 00:03:45,650 --> 00:03:51,290 our terminal a 404 error, meaning there was no page for that particular URL route. 57 00:03:51,830 --> 00:03:57,230 Now I should point out, if you check out the documentation, there are two main pages I want you to 58 00:03:57,230 --> 00:03:57,890 be aware of. 59 00:03:58,280 --> 00:04:04,190 One is the documentation on writing views, so it's just the general topic on writing views. 60 00:04:04,550 --> 00:04:09,350 It talks about a simple view stuff that we've already talked about, but it also has a section on returning 61 00:04:09,350 --> 00:04:09,900 errors. 62 00:04:09,920 --> 00:04:14,450 So the main one that you start off with is HTP response not found. 63 00:04:14,870 --> 00:04:20,029 However, as you continue developing your website would be nice is to switch this out for some sort 64 00:04:20,029 --> 00:04:22,100 of generic 404 exception. 65 00:04:22,520 --> 00:04:28,550 Otherwise, you'd have to keep automatically defining somehow the specific errors you want for every 66 00:04:28,550 --> 00:04:29,210 single view. 67 00:04:29,570 --> 00:04:35,690 Instead, it would be nice if you could just write HTP four or four and then say something like, Hey, 68 00:04:35,690 --> 00:04:40,250 this page doesn't exist or connect it to some 404 template you have later on. 69 00:04:40,670 --> 00:04:46,790 I should also note that there are many subclasses that are not just HTP response and HTP response not 70 00:04:46,790 --> 00:04:47,180 found. 71 00:04:47,510 --> 00:04:52,310 You can check that out on a link here on this page, where it talks about the URL dispatcher, as well 72 00:04:52,310 --> 00:04:54,620 as the requests and views. 73 00:04:54,950 --> 00:05:00,170 There's a request and response objects page that basically has a list of all the different types of 74 00:05:00,170 --> 00:05:03,680 subclasses inside of HTP response and how it works. 75 00:05:03,980 --> 00:05:06,670 So a lot of what we work with here is on this page. 76 00:05:06,680 --> 00:05:12,380 It's a really long page talks about kind of all the different subclasses of HIV response, all different 77 00:05:12,380 --> 00:05:13,160 methods on that. 78 00:05:13,460 --> 00:05:15,590 So you can see here a severe response subclasses. 79 00:05:15,890 --> 00:05:19,790 There's redirects not modified, but requests a step response gone. 80 00:05:20,120 --> 00:05:27,470 So essentially, all those 404 HTML codes in general, four or three for over 400, 500, etc. the main 81 00:05:27,470 --> 00:05:29,630 ones all have subclasses associated with them. 82 00:05:29,990 --> 00:05:35,420 However, really, what we're looking for is an HTP response not found to be replaced by just raising 83 00:05:35,420 --> 00:05:39,860 some sort of generic for a for code that later on, when we learned about templates, we can actually 84 00:05:39,860 --> 00:05:42,380 connect to a specific 404 page. 85 00:05:42,650 --> 00:05:43,820 So how do we do this? 86 00:05:43,850 --> 00:05:47,720 We're going to come back to our code and we're going to do two things here. 87 00:05:48,500 --> 00:05:51,950 Instead of saying accept return response, not found. 88 00:05:52,640 --> 00:06:03,200 I'm going to raise the HP 404 error and say four or four generic error. 89 00:06:03,530 --> 00:06:07,850 And then later on, when we actually learn about templates, we're going to end up doing is this will 90 00:06:07,850 --> 00:06:14,030 actually be connected to something like our custom 404 HTML template that we can connect to later on. 91 00:06:14,330 --> 00:06:19,730 Right now, though, we can actually just raise it as a simple string in order to use each TDP for a 92 00:06:19,730 --> 00:06:21,710 form when you come back up here and import it. 93 00:06:22,280 --> 00:06:25,290 So we have HTP for four. 94 00:06:27,060 --> 00:06:29,040 And let's make sure that's correct there. 95 00:06:30,650 --> 00:06:34,760 All right, so that should be looking good, that's matching up here with the import. 96 00:06:35,060 --> 00:06:40,970 One thing to note, though, is you actually need to adjust your settings, otherwise you'll still get 97 00:06:40,970 --> 00:06:43,190 some sort of debug page. 98 00:06:43,190 --> 00:06:44,780 So even if we save these changes. 99 00:06:45,110 --> 00:06:48,200 Let me show you what happens before we edit the actual settings file. 100 00:06:48,680 --> 00:06:59,390 So I come back to my website here, and if I refresh, I see Page not found for 04 and it says 404 and 101 00:06:59,390 --> 00:07:00,830 then the term actually put here. 102 00:07:00,860 --> 00:07:01,760 Generic error. 103 00:07:02,150 --> 00:07:05,990 If you scroll down here, you'll notice that it says, Hey, you're seeing this particular error page 104 00:07:06,320 --> 00:07:09,860 because you have debug equal to true in your jingo settings file. 105 00:07:10,220 --> 00:07:13,610 Change that to false and jingo will display a standard for a four page. 106 00:07:13,940 --> 00:07:16,040 So let's experiment a little bit with this. 107 00:07:16,580 --> 00:07:20,150 Later on, we'll talk a lot more about project settings, but right now I do want to talk a little bit 108 00:07:20,150 --> 00:07:20,630 about this. 109 00:07:20,900 --> 00:07:22,340 And there's two things here at the change here. 110 00:07:22,580 --> 00:07:27,470 One is our debug settings and the other is our actual allowed hosts list. 111 00:07:27,880 --> 00:07:28,790 Somebody keep in mind, though. 112 00:07:28,820 --> 00:07:33,830 Whenever you're developing a Django project, you do typically want to have debug equal to true that 113 00:07:33,830 --> 00:07:37,640 we can help debug what's happening with the moral force and to see if it's working. 114 00:07:37,640 --> 00:07:42,620 As you expected, when you deploy a website, you definitely want to have debug equals to false. 115 00:07:42,860 --> 00:07:47,180 Otherwise, your users will get some sort of page like this, which gives way too much information about 116 00:07:47,180 --> 00:07:48,920 the website operations to the public. 117 00:07:49,310 --> 00:07:52,550 So we're going to come back to our Visual Studio code. 118 00:07:53,000 --> 00:07:54,290 Go to settings that pie. 119 00:07:55,770 --> 00:08:01,020 And let's actually kill the websites we're going to control, seeing my terminal to not have the website 120 00:08:01,020 --> 00:08:01,650 run anymore. 121 00:08:02,100 --> 00:08:07,860 And we're going to say debug is equal to false and again, security warning don't run debug turn on 122 00:08:07,860 --> 00:08:13,950 in production because there's a debug editing tool and it gives way too much power to any person visiting 123 00:08:13,950 --> 00:08:14,460 your website. 124 00:08:14,880 --> 00:08:19,110 The other thing is, when you have debug equal to false, you need to actually tell Django which hosts 125 00:08:19,110 --> 00:08:19,650 are allowed. 126 00:08:21,020 --> 00:08:26,090 Now, because I'm running this locally, I'm simply going to say the following host is allowed. 127 00:08:26,420 --> 00:08:31,730 It's the one two seven zero zero one that we've been running off of. 128 00:08:31,760 --> 00:08:35,480 So remember, we're running off of this right here, so I'm going to say that's an allowed host. 129 00:08:36,260 --> 00:08:37,380 Save that change. 130 00:08:37,400 --> 00:08:39,380 Let's run our site again. 131 00:08:40,220 --> 00:08:42,080 OK, so the site is now running. 132 00:08:42,289 --> 00:08:47,780 I'm going to come back here and let's refresh the arts page and we see we get not found. 133 00:08:47,900 --> 00:08:50,030 The requested resource was not found on the server. 134 00:08:50,330 --> 00:08:54,730 So that is essentially Django's 404 page that a user would see. 135 00:08:54,740 --> 00:08:58,460 How do we deploy this in real life with debugging turned off? 136 00:08:58,880 --> 00:08:59,210 OK. 137 00:08:59,720 --> 00:09:03,470 So what I'm going to do is turn back here to debug. 138 00:09:04,460 --> 00:09:09,630 Set that equal to true again for the rest of these lectures, and we can delete this allowed hosts. 139 00:09:09,650 --> 00:09:10,700 That's not necessary anymore. 140 00:09:11,210 --> 00:09:12,380 Go ahead and save that. 141 00:09:12,380 --> 00:09:16,430 We'll talk a lot more about settings in general later on, but let's do a quick review of everything 142 00:09:16,430 --> 00:09:23,210 we covered in this particular lecture so you can always use a try except statement in order to take 143 00:09:23,210 --> 00:09:28,400 into account the fact that a client may visit something that doesn't actually exist in the beginning. 144 00:09:28,400 --> 00:09:33,380 You may just want to use it to response not found, especially if you're debugging things later on. 145 00:09:33,380 --> 00:09:36,740 Which you're going to want to do is use some sort of generic HTP for. 146 00:09:37,490 --> 00:09:40,820 And later on, we'll link it to our own custom forum for each HTML template. 147 00:09:41,150 --> 00:09:41,480 All right. 148 00:09:41,630 --> 00:09:42,470 That's it for this lecture. 149 00:09:42,650 --> 00:09:43,460 I'll see you at the next one.