WEBVTT 00:00.880 --> 00:01.480 Okay. 00:01.690 --> 00:10.210 So far we display a dummy text here in our web application, but it has nothing to do with what we have 00:10.210 --> 00:13.650 in our Django, which is inside our models. 00:13.660 --> 00:18.460 We have something that we can actually use and that's coming from the database. 00:18.460 --> 00:22.360 So we seen that book already in the admin page. 00:22.360 --> 00:26.620 And let's go to the admin and let's do something there. 00:27.130 --> 00:28.540 So if I go admin. 00:31.570 --> 00:33.460 I have just one book here. 00:33.460 --> 00:34.960 I can add another one. 00:35.770 --> 00:45.780 Lord of the Ring or whatever some description goes here and so on. 00:45.790 --> 00:51.790 The price, I can have it for one and publish I can do it today is publish. 00:51.790 --> 00:52.390 It is. 00:52.420 --> 00:54.610 And then I will just leave it there. 00:54.610 --> 00:57.940 I'll make it a bigger screen and I will save it. 00:57.940 --> 00:59.470 So we have two books. 00:59.470 --> 01:06.010 One book is Hobbit and another book is Lord of the Ring. 01:06.010 --> 01:08.680 So that's what we have in our database now. 01:08.680 --> 01:13.750 So let's come back to our application here and goes to the views. 01:13.750 --> 01:20.530 And what we can do actually is we can use whatever is in our database and we can do something about 01:20.530 --> 01:22.540 it anywhere in our application. 01:22.540 --> 01:27.280 It doesn't have to be views, but views is a very good candidate to use it because we can actually grab 01:27.280 --> 01:33.620 something from our database and push it to our view, which is displayed on the screen for the user 01:33.620 --> 01:34.580 and what we can do. 01:34.580 --> 01:36.380 First, we need to import. 01:36.380 --> 01:42.920 So from dot models, dot always means from the current folder, we are inside the views. 01:42.950 --> 01:48.980 As you can see here, model synthesis is in the same folder, so we'll import from the models and then 01:48.980 --> 01:50.810 we'll import book. 01:50.810 --> 01:54.500 So the book is available for us now. 01:54.590 --> 02:03.650 And then the book was just a this class here that has all of this included. 02:03.650 --> 02:09.350 But what we can do here is we can actually reference some some books here. 02:09.350 --> 02:10.670 So I will do books. 02:11.590 --> 02:14.140 And then it will be equal to something. 02:14.140 --> 02:25.480 And in Django, we can reference the model like Doc, which is name of the class book and then objects. 02:28.290 --> 02:31.680 And then we can do, for example, all. 02:32.130 --> 02:33.350 So what does it mean? 02:33.360 --> 02:41.850 We're taking books, our model, we reference all objects of that model and then we want to select all 02:41.850 --> 02:43.830 of them and books now. 02:43.860 --> 02:47.160 Now they represent the set of our books. 02:47.160 --> 02:52.430 So what we can do here is we can actually create a new string. 02:52.440 --> 03:01.080 So output, I can name it whatever I like, but I will do a format here, which is just a formatting 03:01.080 --> 03:04.050 the string and we'll say we have. 03:04.940 --> 03:11.120 And then that many books in database. 03:11.690 --> 03:16.850 So what's happening here is actually I format the string. 03:16.850 --> 03:25.400 And inside here what I can do is I can inject length, which is length of our array of books. 03:25.400 --> 03:31.040 And we can we will be able to see how many books are in our database. 03:31.040 --> 03:38.300 So instead of race returning this string, I can return our new output. 03:38.960 --> 03:40.520 I need to reference self. 03:41.120 --> 03:42.350 Self output. 03:42.350 --> 03:45.590 Which is because this output is already on this class. 03:45.590 --> 03:48.020 So that means it's available on self. 03:48.020 --> 03:50.900 Self is always referencing to the class. 03:51.050 --> 03:54.610 So we will response this output. 03:54.620 --> 04:03.350 This output is a formatted string and inside string we'll just inject inject length of the books, which 04:03.350 --> 04:07.830 is how many books we have altogether because we select all the books here. 04:07.830 --> 04:15.000 We apply this, assign this to to this variable, and this variable will be displayed here as a length, 04:15.000 --> 04:16.590 which is how many books we have. 04:16.620 --> 04:24.330 So if I will refresh it now, come back to our browser and then we need to go to our previous URL, 04:24.330 --> 04:28.920 which was demo and then another that was our class. 04:28.950 --> 04:32.760 We have to that many books in database. 04:33.390 --> 04:38.520 Uh, actually the, the string makes no sense, so I will change it quickly. 04:38.910 --> 04:41.070 I can do it like that. 04:41.070 --> 04:43.800 So we have two books in database. 04:44.490 --> 04:47.220 I go here, refresh it, we have two books in database. 04:47.220 --> 04:49.380 Indeed, we have two books in database. 04:49.380 --> 04:56.610 So what is happening here is books, objects, all select all books in our system. 04:56.610 --> 05:00.600 So using method all will select all of them. 05:00.930 --> 05:04.440 We have other options and I will show you in a second what we can do. 05:04.440 --> 05:12.000 Actually, here is we can do print, we can do for book in books. 05:15.150 --> 05:19.410 And then we can do something about this, let's say our output. 05:21.710 --> 05:22.670 Will be. 05:23.270 --> 05:24.290 We have. 05:26.790 --> 05:27.600 Book. 05:29.050 --> 05:34.290 And then I can reference any field from that book. 05:34.300 --> 05:37.690 So what I can do is. 05:39.000 --> 05:46.770 I can concatenate, I will need to create some kind of writing a lot of things here at the moment. 05:48.110 --> 05:50.570 I will explain you in a second what I'm doing. 05:54.650 --> 06:00.770 And if I'll do it like that, Let's see what we have so far. 06:02.450 --> 06:08.000 So we have Hobbit book in database and we have Lords of the Ring book in database. 06:08.000 --> 06:09.980 So why we are seeing this? 06:10.010 --> 06:18.170 We are seeing this because first I set up an empty string as an output and then for each book in books, 06:18.170 --> 06:26.690 this is my local variable that is created when I do a loop inside books, which is set of all our books 06:26.690 --> 06:27.590 in the system. 06:27.590 --> 06:35.120 And then for each book I just concatenate a new string to our output, which is at the beginning empty. 06:35.120 --> 06:42.830 So we do, we have and then I can reference this book title inside and the book in database. 06:42.830 --> 06:48.740 That's supposed to be a new line, but I think I need to use another slash. 06:49.160 --> 06:50.060 Or maybe I'm not. 06:50.300 --> 06:51.290 I'm wrong. 06:52.930 --> 06:54.490 Just let me double check. 06:55.780 --> 06:57.930 Now, the double slash doesn't work. 06:57.940 --> 07:00.100 And so what? 07:00.100 --> 07:00.940 I can try. 07:00.940 --> 07:01.690 I can try. 07:01.720 --> 07:04.540 Maybe break. 07:10.050 --> 07:11.700 An email break will work. 07:11.700 --> 07:12.180 So. 07:12.180 --> 07:18.930 So what we are doing here is every time we have a new book in our set, then we'll concatenate to the 07:18.930 --> 07:26.910 string and we will put we have book title book in our database and that's what is printed. 07:26.910 --> 07:32.160 So every time we go through the books, then we display this book title. 07:32.160 --> 07:37.740 And on this book we have all the different fields available. 07:37.740 --> 07:42.810 So cover description is published price, everything is available. 07:42.810 --> 07:44.160 So we have an access to this. 07:44.190 --> 07:49.590 We don't need to print it here, but if we need to do something with any of this, we can do it. 07:49.590 --> 07:57.570 So I will leave it as title because it's a good thing to display and I will just save it once again 07:57.570 --> 08:00.480 and let's come back here and memorize what's here. 08:00.480 --> 08:04.980 So we have Hobbit book in database and we have Lord of the Ring book in database. 08:04.980 --> 08:12.430 Let's add some extra information book, and then we can do with it. 08:13.390 --> 08:24.100 And then I can include ID, So book.id ID by default is added to each model we have, despite the fact 08:24.100 --> 08:25.780 we don't have ID here. 08:25.780 --> 08:27.640 This will be added by Django. 08:27.670 --> 08:33.430 Each object in our database has has its own ID and it is unique. 08:33.430 --> 08:36.640 It started from one and it's incrementing for every new record. 08:36.640 --> 08:38.500 So one, two, three and so on. 08:38.500 --> 08:42.730 So we this is index for our records in databases. 08:43.120 --> 08:44.770 So let's go back to views. 08:44.770 --> 08:52.450 I will save it and if I will come back here and refresh it, you can see The Hobbit book with ID one 08:52.450 --> 08:55.810 and then we have Lord of the Ring book with ID two. 08:55.810 --> 09:03.700 And also I can show you that if I will go to this URL and then slash admin. 09:05.560 --> 09:06.760 And go into the books. 09:06.760 --> 09:11.180 If I will click on this book, you can see one that's actually ID. 09:11.320 --> 09:18.010 This is not represented as a proper string because we haven't picked any field that should be printed 09:18.010 --> 09:18.370 here. 09:18.370 --> 09:25.300 This is just an object, but this one is ID, So if I click here, you can see in the URL we have book, 09:25.420 --> 09:28.270 then ID one and then change. 09:28.270 --> 09:35.410 So this Django admin also recognized this ID, so this is ID one if I will go books. 09:35.500 --> 09:39.190 And here you can see in the URL is ID two. 09:39.190 --> 09:42.400 So this ID we also have then access to this. 09:42.400 --> 09:47.680 So we have two books, hop it with ID one and lots of the ring ID two. 09:48.100 --> 09:54.670 So I'll show you now what other options we have, methods that we can use in the objects. 09:54.670 --> 09:56.650 So all will select all. 09:56.650 --> 09:59.860 And then I will show you a few different methods. 09:59.860 --> 10:06.380 So all we'll select all all records in our database, but we have other options, like, for example, 10:06.380 --> 10:07.100 filter. 10:07.100 --> 10:13.910 What we can do in filter is we can pass some extra parameters to the filter method and it will return 10:13.910 --> 10:18.920 only that object that will meet the criteria that we pass it here. 10:18.920 --> 10:26.990 So for example, what we can do here is we can use any of these fields to do some validation on it. 10:26.990 --> 10:30.140 So what I can do is I can select this published. 10:31.460 --> 10:35.090 For example and I will do is published. 10:37.070 --> 10:37.820 True. 10:38.300 --> 10:43.330 So I will select only this books that are published. 10:43.340 --> 10:51.740 And then if I will go back here and refresh it, you can see lots of the ring Only with ID two is selected 10:51.740 --> 10:54.500 here because lots of the ring is published. 10:54.500 --> 10:55.580 It's marked here. 10:55.580 --> 10:58.790 But if we go back to The Hobbit one, it's not published. 10:58.790 --> 11:05.120 So if I will click publish here, it's published and save it and come back to our view and refresh it. 11:07.430 --> 11:17.270 Actually let's come back here is published, and then we have our Lord of the Ring is published as well. 11:19.170 --> 11:21.270 So we don't see the previous one. 11:28.160 --> 11:35.030 And then I refresh the application and you can see here two books are here because one is published 11:35.270 --> 11:38.600 and another one is also published. 11:38.600 --> 11:44.900 So if I only publish one, I had to refresh the application just because to refresh the database. 11:44.900 --> 11:47.420 But normally you shouldn't do it. 11:47.420 --> 11:48.500 You don't have to do it. 11:48.500 --> 11:53.570 So save one is published, one is not, and then let's try to refresh it. 11:53.570 --> 11:57.800 It might be actually cached here by our browser, this view. 11:57.830 --> 12:02.330 So we might see the old version that is cached. 12:02.330 --> 12:06.920 But if I will go here and then I will refresh the server. 12:08.720 --> 12:11.270 And then I will refresh it here. 12:11.270 --> 12:15.110 You can see now we have a better view. 12:15.140 --> 12:23.330 So basically coming back to here, the filter can filter our records based on some conditions what we 12:23.330 --> 12:24.050 have here. 12:24.050 --> 12:31.940 So what we can also use different things so we can check if a string contains something, we can check 12:31.940 --> 12:35.420 if the value is greater than something or less than something. 12:35.420 --> 12:39.830 And we have a bunch of different options here available in the filter. 12:39.830 --> 12:42.260 So that's a second option. 12:42.260 --> 12:44.360 The third option is Cat. 12:44.720 --> 12:55.970 What Cat will do is get Will brings us just one object all and filter brings us back a set of books. 12:55.970 --> 12:59.900 In this case, Cat will bring only one, so we can't actually do this. 13:00.170 --> 13:05.600 So we need to put a comment there and here because this won't be allowed. 13:05.630 --> 13:10.170 The get always brings one record. 13:10.380 --> 13:19.050 So what I can do here is I can say give me a book of ID two and that will be just one book here. 13:19.590 --> 13:27.660 And then instead of having this output here, what I can do is actually I can copy this one. 13:30.360 --> 13:31.680 And I will put it here. 13:31.680 --> 13:37.050 So we have book title with ID here. 13:37.320 --> 13:38.850 So I will save it now. 13:38.850 --> 13:44.220 And we this time we select just one book with ID two. 13:44.760 --> 13:48.840 I come here and you can see lots of the ring with ID two. 13:48.870 --> 13:56.400 If I will go here and change this ID to one and I will save it and I'm coming back here. 13:56.430 --> 13:57.600 I will refresh it. 13:57.630 --> 14:00.240 It's still the caching problem in the browser. 14:00.240 --> 14:04.080 So what I will do is refresh the the server. 14:05.040 --> 14:06.590 And coming back here. 14:06.600 --> 14:09.840 And then you can see Hobbit with Book one. 14:10.020 --> 14:19.020 So this book objects give us opportunity to access our database and the records in our database. 14:19.020 --> 14:21.180 So book dot objects dot. 14:21.180 --> 14:29.430 And then we have three methods, all selecting all filter returns set of records from our database based 14:29.430 --> 14:36.960 on some conditions and get you also pass some conditions here and that will return only one record. 14:37.800 --> 14:40.280 So that will be it in the next videos. 14:40.290 --> 14:49.200 We will also also show you how the built in Django solution is much better and much more performant 14:49.200 --> 14:51.870 than what we are doing now here manually.