1 1 00:00:02,150 --> 00:00:03,770 Hey guys welcome back. 2 2 00:00:03,770 --> 00:00:07,490 In this video we're going to be adding a few more methods 3 3 00:00:07,490 --> 00:00:11,610 to our model just to finalise it and make sure that the new 4 4 00:00:11,610 --> 00:00:14,940 model classes that we'll be creating all have 5 5 00:00:14,940 --> 00:00:19,000 these methods, and there are gonna be a few of them. 6 6 00:00:19,000 --> 00:00:23,450 For example we're going to have something like save to Mongo 7 7 00:00:23,450 --> 00:00:25,200 which is going to be in every model. 8 8 00:00:25,200 --> 00:00:28,520 We're going to move that to our model class, 9 9 00:00:28,520 --> 00:00:31,800 we're gonna have things like get by ID 10 10 00:00:31,800 --> 00:00:34,600 which is probably gonna be necessary in every model 11 11 00:00:34,600 --> 00:00:39,174 and even if not all models use this get by ID, 12 12 00:00:39,174 --> 00:00:42,630 most of them will so it's also a good thing 13 13 00:00:42,630 --> 00:00:45,143 to move into our model base class. 14 14 00:00:46,210 --> 00:00:48,160 So I'm gonna do just that, I'm going to implement 15 15 00:00:48,160 --> 00:00:50,750 a few methods into this model base class 16 16 00:00:50,750 --> 00:00:52,443 and then we're gonna talk about them. 17 17 00:01:07,860 --> 00:01:10,720 So I added these two methods now, 18 18 00:01:10,720 --> 00:01:14,520 and we're got save to Mongo and remove from Mongo. 19 19 00:01:14,520 --> 00:01:19,150 Save to Mongo is going to call database.update, 20 20 00:01:19,150 --> 00:01:21,070 this is something that doesn't exist yet in our 21 21 00:01:21,070 --> 00:01:26,070 database class and update is going to insert a new thing 22 22 00:01:26,240 --> 00:01:30,090 into the database, unless there is already 23 23 00:01:30,090 --> 00:01:33,543 something in the database matching this underscore ID. 24 24 00:01:34,490 --> 00:01:37,660 So we're gonna run this search and if something comes back 25 25 00:01:37,660 --> 00:01:40,750 we're gonna update that thing instead of inserting 26 26 00:01:40,750 --> 00:01:43,800 a new one, this is called upserting, 27 27 00:01:43,800 --> 00:01:46,670 and it's a very common thing to do when you're dealing 28 28 00:01:46,670 --> 00:01:49,010 with unique elements. 29 29 00:01:49,010 --> 00:01:51,090 Remove from Mongo is going to do just that. 30 30 00:01:51,090 --> 00:01:53,790 It's going to take something away from MongoDB, 31 31 00:01:53,790 --> 00:01:56,150 all of the things that match this query here, 32 32 00:01:56,150 --> 00:01:58,390 all of the things that have this underscore ID 33 33 00:01:58,390 --> 00:02:00,280 are going to be removed. 34 34 00:02:00,280 --> 00:02:01,800 So we're gonna implement that in a second, 35 35 00:02:01,800 --> 00:02:04,900 but something else that we've got is self.collection 36 36 00:02:04,900 --> 00:02:09,020 and I talked earlier on about cls.collection 37 37 00:02:09,020 --> 00:02:13,470 and how we'd moved collection away from the init method 38 38 00:02:13,470 --> 00:02:16,533 and into a class level property. 39 39 00:02:17,720 --> 00:02:19,990 Can you still access the class property 40 40 00:02:19,990 --> 00:02:23,560 using self.collection, yes so this is 41 41 00:02:23,560 --> 00:02:25,250 a perfectly fine thing to do 42 42 00:02:25,250 --> 00:02:28,290 and it still allows us to access the current object 43 43 00:02:28,290 --> 00:02:30,300 selection property even if it's stored 44 44 00:02:30,300 --> 00:02:33,500 at the class level, rather than hard coding 45 45 00:02:33,500 --> 00:02:35,820 a specific string in here. 46 46 00:02:35,820 --> 00:02:38,393 So this is the way to access that, 47 47 00:02:39,330 --> 00:02:44,330 now you'll notice that self. underscore ID is unresolved 48 48 00:02:44,393 --> 00:02:49,000 and it's not easy to get rid of this warning 49 49 00:02:49,000 --> 00:02:51,540 because we don't want to do self. underscore ID 50 50 00:02:51,540 --> 00:02:54,820 equals something, we don't wanna do that. 51 51 00:02:54,820 --> 00:02:59,820 Because then we are going to still be setting it here 52 52 00:03:00,680 --> 00:03:03,570 and that's gonna be a little confusing. 53 53 00:03:03,570 --> 00:03:05,940 So for now we're gonna leave it as is. 54 54 00:03:05,940 --> 00:03:07,500 We're just going to accept that this 55 55 00:03:07,500 --> 00:03:10,950 is an unresolved attribute in the model class 56 56 00:03:10,950 --> 00:03:13,390 but it's going to be fine in the sub-class. 57 57 00:03:13,390 --> 00:03:16,844 Because they do have a self. underscore ID. 58 58 00:03:16,844 --> 00:03:21,844 Let's go over to our database and add those two methods. 59 59 00:03:23,040 --> 00:03:26,973 These are gonna be update and remove. 60 60 00:03:37,210 --> 00:03:38,950 So here's now we're gonna do it, 61 61 00:03:38,950 --> 00:03:41,680 we're going to receive the collection that 62 62 00:03:41,680 --> 00:03:45,160 we wanna modify, the things that we wanna look for 63 63 00:03:45,160 --> 00:03:47,110 and potentially update, 64 64 00:03:47,110 --> 00:03:50,630 and what we want to update them with. 65 65 00:03:50,630 --> 00:03:52,917 So everything that matches this query, 66 66 00:03:52,917 --> 00:03:56,090 all of the contents of that thing 67 67 00:03:56,090 --> 00:03:58,733 will be replaced by this data, 68 68 00:04:00,070 --> 00:04:03,002 and then we're gonna do update the query with data 69 69 00:04:03,002 --> 00:04:07,220 and we're gonna pass in this upsert equals true argument 70 70 00:04:07,220 --> 00:04:10,250 and what this is gonna do is add a new element 71 71 00:04:11,090 --> 00:04:14,650 with this data if the query returned nothing, 72 72 00:04:14,650 --> 00:04:18,140 and remember this is all PyMongo this module we've installed 73 73 00:04:18,140 --> 00:04:21,320 for interacting with MongoDB and what we're doing is 74 74 00:04:21,320 --> 00:04:24,463 we're just defining a slightly easier way of accessing it. 75 75 00:04:33,910 --> 00:04:36,300 And what we've done here is we have created 76 76 00:04:36,300 --> 00:04:39,950 the remove method and this is going to call 77 77 00:04:39,950 --> 00:04:44,717 the remove method in PyMongo and it's going to return 78 78 00:04:44,717 --> 00:04:49,160 all of the things that were removed matching this query. 79 79 00:04:49,160 --> 00:04:51,420 We're probably not gonna use anything that's being returned 80 80 00:04:51,420 --> 00:04:53,180 from this but nonetheless, 81 81 00:04:53,180 --> 00:04:54,930 it can be interesting to have that. 82 82 00:04:56,000 --> 00:04:57,660 So now we have our two methods here 83 83 00:04:57,660 --> 00:05:01,790 to update or insert and to remove we can go back 84 84 00:05:01,790 --> 00:05:03,983 to our model and continue adding. 85 85 00:05:15,000 --> 00:05:19,760 So what I've done now is I've added a find one by method, 86 86 00:05:19,760 --> 00:05:22,530 what it's gonna do is it's going to allow us to do something 87 87 00:05:22,530 --> 00:05:26,720 like item.find one by URL HTTPS 88 88 00:05:27,680 --> 00:05:29,877 you know whatever your URL is. 89 89 00:05:30,920 --> 00:05:34,900 This is then going to go into the database, 90 90 00:05:34,900 --> 00:05:38,260 it's gonna find one with the collection that's 91 91 00:05:38,260 --> 00:05:41,030 relevant to that class, in this case it's gonna be items 92 92 00:05:41,030 --> 00:05:46,030 and then it's gonna find it with URL is HTTPS bla.com 93 93 00:05:48,040 --> 00:05:50,150 so that's what it's gonna do it's gonna allow us 94 94 00:05:50,150 --> 00:05:54,090 to very easily perform a one item search 95 95 00:05:54,090 --> 00:05:56,740 in the database, just by using this method here 96 96 00:05:56,740 --> 00:05:58,940 and this is gonna be really useful later on. 97 97 00:06:00,550 --> 00:06:04,090 As a counterpart to that, we're gonna have find many by 98 98 00:06:07,560 --> 00:06:09,420 and all that's gonna do is exactly the same thing 99 99 00:06:09,420 --> 00:06:11,330 but instead of returning a single element 100 100 00:06:11,330 --> 00:06:13,603 it's gonna return a list of objects. 101 101 00:06:19,990 --> 00:06:21,640 Just like that. 102 102 00:06:21,640 --> 00:06:24,210 Now it's doing the same stuff but instead of finding one 103 103 00:06:24,210 --> 00:06:26,970 it's gonna find many and then it's gonna give us 104 104 00:06:26,970 --> 00:06:29,933 an object for each of the things that have been found. 105 105 00:06:31,750 --> 00:06:36,203 Now the last one that we're gonna add is the get by ID, 106 106 00:06:39,040 --> 00:06:44,040 and notice how I'm not calling this find by ID. 107 107 00:06:45,260 --> 00:06:48,380 Because the assumption is that when you have 108 108 00:06:48,380 --> 00:06:52,190 an ID property you are gonna have an element with that 109 109 00:06:52,190 --> 00:06:54,830 underscore ID otherwise it doesn't really make sense 110 110 00:06:54,830 --> 00:06:57,920 that you'd have that ID, after all if you don't 111 111 00:06:57,920 --> 00:07:00,160 have an element with underscore ID where did you get 112 112 00:07:00,160 --> 00:07:03,410 that underscore ID from in the first place? 113 113 00:07:03,410 --> 00:07:05,030 And so that's the assumption there, if you do have 114 114 00:07:05,030 --> 00:07:06,390 an underscore ID what you're going to do is you're 115 115 00:07:06,390 --> 00:07:08,633 going to go into the database 116 116 00:07:08,633 --> 00:07:10,800 and get the element that has that underscore ID. 117 117 00:07:10,800 --> 00:07:14,433 So we're gonna say return cls database.find one. 118 118 00:07:22,350 --> 00:07:26,483 Alright so you can see that this is gonna be like that, 119 119 00:07:28,010 --> 00:07:30,520 this is all it's doing is it's going through the database 120 120 00:07:30,520 --> 00:07:33,530 into the collection that we've got for this current class, 121 121 00:07:33,530 --> 00:07:36,910 be that item or alert and then it's going to search 122 122 00:07:36,910 --> 00:07:39,630 for underscore ID, it's gonna return an object. 123 123 00:07:39,630 --> 00:07:42,340 Now we already have a line that does something 124 124 00:07:42,340 --> 00:07:45,323 very similar to this, which is this one. 125 125 00:07:46,270 --> 00:07:48,560 It does exactly the same thing but you can define 126 126 00:07:48,560 --> 00:07:51,270 the attribute at the value that you want, 127 127 00:07:51,270 --> 00:07:54,570 so instead of defining this line ourselves 128 128 00:07:54,570 --> 00:07:58,440 we are going to return cls.find one by 129 129 00:07:58,440 --> 00:08:03,170 and underscore ID, underscore ID, why? 130 130 00:08:03,170 --> 00:08:05,860 Well I mean just that we have this method here 131 131 00:08:05,860 --> 00:08:07,340 so we might as well use it. 132 132 00:08:07,340 --> 00:08:10,170 If we do want to change the way that we interact 133 133 00:08:10,170 --> 00:08:13,270 with the database or maybe we wanna change find one. 134 134 00:08:13,270 --> 00:08:16,810 We wanna rename it into something else or whatever 135 135 00:08:16,810 --> 00:08:19,380 we only have to do that in one place. 136 136 00:08:19,380 --> 00:08:22,920 Because that's the method that's responsible for finding one 137 137 00:08:23,760 --> 00:08:27,163 so there we go this is how you should do that. 138 138 00:08:28,560 --> 00:08:31,250 Now that we have these methods we are ready 139 139 00:08:31,250 --> 00:08:33,430 to implement any other model 140 140 00:08:33,430 --> 00:08:36,490 and all we have to define really is just the collection 141 141 00:08:36,490 --> 00:08:38,370 and the data is going to be stored in it 142 142 00:08:38,370 --> 00:08:40,510 and what the JSON method is going to return 143 143 00:08:40,510 --> 00:08:44,220 and this superclass is going to deal with all 144 144 00:08:44,220 --> 00:08:46,950 the logistical issues of interacting with 145 145 00:08:46,950 --> 00:08:49,670 the database and you know finding things 146 146 00:08:49,670 --> 00:08:53,623 and things like that, so this is going to be really great. 147 147 00:08:54,960 --> 00:08:56,580 We're ready to move on to the next video, 148 148 00:08:56,580 --> 00:08:59,043 so thanks for joining me and I'll see you there.