WEBVTT 1 00:00:01.710 --> 00:00:03.220 Hi, guys, and welcome back. 2 00:00:03.220 --> 00:00:04.630 In this video, we're going to learn 3 00:00:04.630 --> 00:00:06.753 about decorators with parameters. 4 00:00:06.753 --> 00:00:09.110 Now, this is slightly different than the last video 5 00:00:09.110 --> 00:00:11.750 where we looked at decorating functions with parameters, 6 00:00:11.750 --> 00:00:13.310 now we're going to add parameters 7 00:00:13.310 --> 00:00:15.400 to the decorators themselves. 8 00:00:15.400 --> 00:00:16.300 Let's get started. 9 00:00:17.220 --> 00:00:19.880 Here, we have our make_secure decorator. 10 00:00:19.880 --> 00:00:23.530 And now, we are looking at two different functions. 11 00:00:23.530 --> 00:00:26.310 One get_admin_password that is decorated, 12 00:00:26.310 --> 00:00:29.510 and get_dashboard_password, which is also decorated. 13 00:00:29.510 --> 00:00:31.600 But now, I want the get_admin_password 14 00:00:31.600 --> 00:00:33.840 function to only be accessible by admins 15 00:00:33.840 --> 00:00:35.700 and the get_dashboard_password to only 16 00:00:35.700 --> 00:00:38.170 be accessible by users. 17 00:00:38.170 --> 00:00:41.180 So if you're a guest, you will get access to neither, 18 00:00:41.180 --> 00:00:43.740 but if you're a user, you'll get access to this one. 19 00:00:43.740 --> 00:00:46.490 And if you're an admin, you'll get access to this one. 20 00:00:46.490 --> 00:00:48.023 So how do we do this? 21 00:00:48.023 --> 00:00:52.040 Well, we have a make_secure decorator here, 22 00:00:52.040 --> 00:00:55.840 and notice that when this gets called, 23 00:00:55.840 --> 00:00:58.480 what happens is the make_secure decorator 24 00:00:58.480 --> 00:01:01.450 gets applied to get_admin_password. 25 00:01:01.450 --> 00:01:05.180 But there are no brackets after this make_secure. 26 00:01:05.180 --> 00:01:07.530 Now, what we're going to do is we're going to create 27 00:01:07.530 --> 00:01:11.660 a function that will return the decorator, 28 00:01:11.660 --> 00:01:14.680 but it will allow us to check for the access level. 29 00:01:14.680 --> 00:01:15.800 Now, here's that's gonna go. 30 00:01:15.800 --> 00:01:17.300 It's a little bit complicated. 31 00:01:18.210 --> 00:01:22.260 We're going to create another decorator, 32 00:01:22.260 --> 00:01:25.057 and this one is going to take in an access_level. 33 00:01:26.364 --> 00:01:30.390 The rest of all of this is going to go inside that. 34 00:01:30.390 --> 00:01:34.253 And this one here is going to return make_secure. 35 00:01:35.440 --> 00:01:38.870 So we have added a third level of function, 36 00:01:38.870 --> 00:01:40.869 and I know this is quite confusing, 37 00:01:40.869 --> 00:01:45.350 but now what we've got is not really a decorator. 38 00:01:45.350 --> 00:01:46.970 Now, I'm going to actually change the name 39 00:01:46.970 --> 00:01:49.800 of these functions because the outer function, 40 00:01:49.800 --> 00:01:52.400 it's not really a decorator anymore. 41 00:01:52.400 --> 00:01:55.040 This one here is a decorator now. 42 00:01:55.040 --> 00:01:57.640 This one is a factory, essentially, 43 00:01:57.640 --> 00:02:00.870 a function that is used to create a decorator. 44 00:02:00.870 --> 00:02:03.200 But what we have is a function call, 45 00:02:03.200 --> 00:02:05.040 that we give it an access_level, 46 00:02:05.040 --> 00:02:07.530 and then it creates a decorator and returns it. 47 00:02:07.530 --> 00:02:10.720 So now we have to put the brackets in here. 48 00:02:10.720 --> 00:02:13.240 And the order is very important. 49 00:02:13.240 --> 00:02:15.970 The function call happens first, 50 00:02:15.970 --> 00:02:19.690 and then the result is applied as a decorator. 51 00:02:19.690 --> 00:02:21.630 So the function call happens first. 52 00:02:21.630 --> 00:02:23.940 This will run in its entirety. 53 00:02:23.940 --> 00:02:26.330 We will define the decorator function, 54 00:02:26.330 --> 00:02:28.180 and we will return it. 55 00:02:28.180 --> 00:02:31.460 Oh, sorry, this should be decorator there, 56 00:02:31.460 --> 00:02:33.600 because we wanna return that function. 57 00:02:33.600 --> 00:02:36.830 So this will run and return the decorator, 58 00:02:36.830 --> 00:02:41.490 and that is the result of calling make_secure, 59 00:02:41.490 --> 00:02:45.770 and then we will apply that decorator into this function. 60 00:02:45.770 --> 00:02:48.610 At the end of the day, the result is the same, 61 00:02:48.610 --> 00:02:53.310 but now we can pass in something like admin in there, 62 00:02:53.310 --> 00:02:56.630 and something like guest in there. 63 00:02:56.630 --> 00:03:01.200 Notice that because this factory does take in a argument, 64 00:03:01.200 --> 00:03:04.313 you need to put the argument and the brackets in there. 65 00:03:05.180 --> 00:03:07.810 The benefit of that is now inside here, 66 00:03:07.810 --> 00:03:09.620 we can check that access level. 67 00:03:09.620 --> 00:03:11.690 So we can say that if the user's access level 68 00:03:11.690 --> 00:03:16.690 is equal to the access level that we want to secure for, 69 00:03:17.460 --> 00:03:19.340 then we have access to the function. 70 00:03:19.340 --> 00:03:21.980 Otherwise, we can say that this user 71 00:03:21.980 --> 00:03:25.520 has no access level permissions, or for that. 72 00:03:25.520 --> 00:03:28.720 So there are no access level permissions for that user. 73 00:03:28.720 --> 00:03:31.010 Now if we want to run these functions, we can do. 74 00:03:31.010 --> 00:03:33.001 Here I've got the get_admin_password 75 00:03:33.001 --> 00:03:34.227 and get_dashboard_password. 76 00:03:34.227 --> 00:03:37.032 We should get no access for either of those. 77 00:03:37.032 --> 00:03:39.212 And then I'm going to change the user to an admin 78 00:03:39.212 --> 00:03:41.730 and run them again, and now we should allow this one, 79 00:03:41.730 --> 00:03:43.216 but not that one. 80 00:03:43.216 --> 00:03:45.419 Let me save that and run it, 81 00:03:45.419 --> 00:03:49.022 and you'll see that you get that problem exactly. 82 00:03:49.022 --> 00:03:51.593 Indeed, we actually have access to the user dashboard there. 83 00:03:51.593 --> 00:03:54.750 We wanna change that, make sure that's for users only 84 00:03:54.750 --> 00:03:56.900 since that was the original intention. 85 00:03:56.900 --> 00:03:58.040 Let's run that again. 86 00:03:58.040 --> 00:04:00.700 And you get no admin permissions for Jose, 87 00:04:00.700 --> 00:04:02.379 no user permissions for Jose. 88 00:04:02.379 --> 00:04:04.980 But Anna does have admin permissions, 89 00:04:04.980 --> 00:04:06.743 but no user permissions. 90 00:04:08.130 --> 00:04:09.730 something that you may wanna look into 91 00:04:09.730 --> 00:04:12.470 to improve this further is, instead of using strings 92 00:04:12.470 --> 00:04:14.520 for your access levels, you can use integers. 93 00:04:14.520 --> 00:04:17.280 So guest can be zero, user can be one, 94 00:04:17.280 --> 00:04:18.650 and admin can be two. 95 00:04:18.650 --> 00:04:20.380 And then, instead of checking a quality here, 96 00:04:20.380 --> 00:04:21.940 you can actually do greater than. 97 00:04:21.940 --> 00:04:24.470 And that'll let admins access the user passwords 98 00:04:24.470 --> 00:04:25.813 as well, if you want that. 99 00:04:28.010 --> 00:04:29.010 That's it for this video. 100 00:04:29.010 --> 00:04:31.520 I wanted to show you how to create decorators 101 00:04:31.520 --> 00:04:32.810 that have parameters. 102 00:04:32.810 --> 00:04:35.240 And I know that they are a bit confusing. 103 00:04:35.240 --> 00:04:37.640 There are three levels of functions, 104 00:04:37.640 --> 00:04:41.040 which make these the most complicated Python code 105 00:04:41.040 --> 00:04:42.740 that you'll see in most Python courses, 106 00:04:42.740 --> 00:04:45.910 and certainly throughout your programming, as well. 107 00:04:45.910 --> 00:04:47.010 But hope you've learned something. 108 00:04:47.010 --> 00:04:48.040 Hope you've enjoyed it. 109 00:04:48.040 --> 00:04:49.790 And I'll see you in the next video.