1 1 00:00:00,810 --> 00:00:02,350 Hi guys, welcome back. 2 2 00:00:02,350 --> 00:00:06,040 In this video we're going to be storing the last price 3 3 00:00:06,040 --> 00:00:09,390 found for an item into a database. 4 4 00:00:09,390 --> 00:00:10,223 The reason for that, 5 5 00:00:10,223 --> 00:00:12,890 is that when a user is looking at their alerts, 6 6 00:00:12,890 --> 00:00:15,670 at the moment they see the alert name, 7 7 00:00:15,670 --> 00:00:17,993 and the item ID and the item URL. 8 8 00:00:18,850 --> 00:00:21,230 But, it would be nice if we could tell them, 9 9 00:00:21,230 --> 00:00:24,860 what the last price was for the item, 10 10 00:00:24,860 --> 00:00:26,400 when they're looking at their screen, 11 11 00:00:26,400 --> 00:00:28,740 without having to, you know, click the item, 12 12 00:00:28,740 --> 00:00:30,940 and find what the price is right now themselves. 13 13 00:00:30,940 --> 00:00:32,660 If a programme can do it for them, 14 14 00:00:32,660 --> 00:00:34,370 that's gonna make their life a little bit easier, 15 15 00:00:34,370 --> 00:00:36,500 it's gonna make things a bit faster. 16 16 00:00:36,500 --> 00:00:41,310 So the plan is to be able to show something like last price, 17 17 00:00:41,310 --> 00:00:46,310 and then have this alert dot item dot price in here. 18 18 00:00:47,230 --> 00:00:48,063 Like that. 19 19 00:00:48,063 --> 00:00:52,453 So we'll say last price, maybe £1000 or £100 or whatever. 20 20 00:00:54,150 --> 00:00:54,983 In order to do that, 21 21 00:00:54,983 --> 00:00:57,670 we do need to store the price on the item. 22 22 00:00:57,670 --> 00:01:00,020 So let's go over to our item model. 23 23 00:01:00,020 --> 00:01:01,490 And, notice that at the moment, 24 24 00:01:01,490 --> 00:01:04,000 we are having this post init, 25 25 00:01:04,000 --> 00:01:06,100 that says self dot price is none. 26 26 00:01:06,100 --> 00:01:09,570 And then, when we call the load price method, 27 27 00:01:09,570 --> 00:01:11,900 we populate self dot price. 28 28 00:01:11,900 --> 00:01:15,270 But, we don't save it to the database, 29 29 00:01:15,270 --> 00:01:17,730 which means that, when we create the item again, 30 30 00:01:17,730 --> 00:01:20,570 such as if we reload the page or whatever, 31 31 00:01:20,570 --> 00:01:23,940 it's not gonna have a price until we call load price again. 32 32 00:01:23,940 --> 00:01:26,390 If we store that in the database, 33 33 00:01:26,390 --> 00:01:30,130 that means that, the latest price that we got, 34 34 00:01:30,130 --> 00:01:32,010 will always be saved there, 35 35 00:01:32,010 --> 00:01:34,010 and when we call load price, 36 36 00:01:34,010 --> 00:01:36,170 what we'll have to do is, we will have to 37 37 00:01:36,170 --> 00:01:39,860 re-save that price into the database, 38 38 00:01:39,860 --> 00:01:41,360 so that the database always has 39 39 00:01:41,360 --> 00:01:43,733 the latest price we retrieved. 40 40 00:01:44,720 --> 00:01:46,210 In this video, 41 41 00:01:46,210 --> 00:01:48,874 we're going to say price is going to be a float, 42 42 00:01:48,874 --> 00:01:50,450 which is going to be a field 43 43 00:01:50,450 --> 00:01:53,170 and the default is going to be none. 44 44 00:01:53,170 --> 00:01:56,420 And, that does exactly the same that, this post init does. 45 45 00:01:56,420 --> 00:01:57,313 It gives us, 46 46 00:01:58,197 --> 00:01:59,510 a float value, 47 47 00:01:59,510 --> 00:02:01,360 but the default is none. 48 48 00:02:01,360 --> 00:02:02,430 There is a difference, 49 49 00:02:02,430 --> 00:02:07,150 which is that now it can be passed in to the init method. 50 50 00:02:07,150 --> 00:02:09,030 Which means that we can take it, 51 51 00:02:09,030 --> 00:02:11,703 and save it here into the JSON method. 52 52 00:02:12,860 --> 00:02:16,030 So that when we load an item from the database, 53 53 00:02:16,030 --> 00:02:18,890 it will automatically have the price, 54 54 00:02:18,890 --> 00:02:20,440 that was saved in the database. 55 55 00:02:22,970 --> 00:02:23,803 Now remember, 56 56 00:02:23,803 --> 00:02:26,090 whenever we call load price, 57 57 00:02:26,090 --> 00:02:29,010 that is going to populate self dot price. 58 58 00:02:29,010 --> 00:02:31,330 But, it's not going to save it to the database 59 59 00:02:31,330 --> 00:02:34,900 unless we call self dot save to Mongo, 60 60 00:02:34,900 --> 00:02:36,500 so we do have to still call that. 61 61 00:02:36,500 --> 00:02:38,300 It's not gonna happen automatically. 62 62 00:02:39,400 --> 00:02:41,120 The last thing we have to do is, 63 63 00:02:41,120 --> 00:02:43,460 when we create a new alert 64 64 00:02:44,430 --> 00:02:45,263 in here, 65 65 00:02:45,263 --> 00:02:47,560 before we save the item to MongoDB, 66 66 00:02:47,560 --> 00:02:49,830 we're going to save item dot load price. 67 67 00:02:49,830 --> 00:02:51,670 And what that's gonna do again is, 68 68 00:02:51,670 --> 00:02:55,530 going to go the site, fetch the price of the item, 69 69 00:02:55,530 --> 00:02:58,000 store it in self dot price, and then, 70 70 00:02:58,000 --> 00:02:59,634 we're gonna save it to MongoDB, 71 71 00:02:59,634 --> 00:03:02,950 and then we're gonna take the user back to our site. 72 72 00:03:02,950 --> 00:03:04,170 Why? 73 73 00:03:04,170 --> 00:03:06,820 So that, when they go to the alerts page, 74 74 00:03:06,820 --> 00:03:09,820 this item will already have a price. 75 75 00:03:09,820 --> 00:03:12,060 Then we won't have had to, you know, call load price on it, 76 76 00:03:12,060 --> 00:03:14,700 using the alert updater, which is the thing, 77 77 00:03:14,700 --> 00:03:17,450 that actually does most of the work in our application. 78 78 00:03:18,750 --> 00:03:21,850 So, now when we create a new item we'll load the price, 79 79 00:03:21,850 --> 00:03:24,350 and then, when the user ever goes back to the alerts, 80 80 00:03:24,350 --> 00:03:27,740 they'll see what the price was when they created the item, 81 81 00:03:27,740 --> 00:03:31,200 or the last time, that we ran the alert updater. 82 82 00:03:31,200 --> 00:03:32,033 And by the way, 83 83 00:03:32,033 --> 00:03:34,840 we are planning on running this alert updater periodically, 84 84 00:03:34,840 --> 00:03:38,000 maybe every few hours, maybe everyday. 85 85 00:03:38,000 --> 00:03:40,033 Just depends on the user, probably. 86 86 00:03:42,000 --> 00:03:43,380 That's it for this video though. 87 87 00:03:43,380 --> 00:03:46,790 We have added the price into our items and, 88 88 00:03:46,790 --> 00:03:48,120 notice how easy it was. 89 89 00:03:48,120 --> 00:03:50,490 We just added a property into the data class, 90 90 00:03:50,490 --> 00:03:52,380 and then saved into to the JSON. 91 91 00:03:52,380 --> 00:03:53,329 And that's it. 92 92 00:03:53,329 --> 00:03:55,170 So, thanks for joining me. 93 93 00:03:55,170 --> 00:03:56,720 I'll see you on the next video.