1 00:00:02,470 --> 00:00:05,670 To ensure that we can add products to the cart, 2 00:00:05,710 --> 00:00:08,940 we need to work on the post cart method here. 3 00:00:08,950 --> 00:00:13,620 The post cart method is responsible for adding new products to the cart. 4 00:00:13,800 --> 00:00:18,560 For this, let's get rid of the existing code there because we'll rewrite it from scratch, 5 00:00:18,790 --> 00:00:23,920 well almost, I'll keep the code where we get the product ID because I still need to do that. 6 00:00:24,940 --> 00:00:25,390 Next 7 00:00:25,420 --> 00:00:31,860 I'll first of all get access to the cart in exactly the same way I did it up there in get cart with request 8 00:00:31,870 --> 00:00:34,310 user get cart and then my then block, 9 00:00:34,340 --> 00:00:44,910 so I'll repeat that and then have then and thereafter also catch here. And catch as always I'll just 10 00:00:45,060 --> 00:00:46,870 log any potential error I get 11 00:00:46,960 --> 00:00:51,250 and in then here I simply have access to the cart. 12 00:00:51,440 --> 00:00:53,420 So now we have the cart available. 13 00:00:53,930 --> 00:01:00,050 Now the third step is that I want to find out if the product I'm trying to add is already part of the 14 00:01:00,050 --> 00:01:03,630 cart because if it is, then I just need to increase the quantity, 15 00:01:03,650 --> 00:01:07,150 if it's not I need to add it with a quantity of one. 16 00:01:07,460 --> 00:01:18,070 So I will return cart get products here with a where condition where I restrict the retrieved products 17 00:01:18,080 --> 00:01:23,240 to the product with my prod Id, like that. 18 00:01:23,260 --> 00:01:29,680 So now I only retrieve that single product and in the next then block, I will get an array of 19 00:01:29,680 --> 00:01:30,120 products 20 00:01:30,130 --> 00:01:36,280 as you learned but we know that this will only hold one product at most, it might even hold no product 21 00:01:36,350 --> 00:01:42,330 if a product with this ID is not part of this cart yet. So here 22 00:01:45,290 --> 00:01:51,550 I'll retrieve my single product as the first element of this array 23 00:01:51,800 --> 00:02:01,630 but first of all I need to check if products length is greater than zero. I'll right this a bit differently, 24 00:02:01,680 --> 00:02:06,300 create a product variable here and assign a value to that variable 25 00:02:06,300 --> 00:02:09,980 if we do have products, otherwise it will stay undefined. 26 00:02:09,990 --> 00:02:17,910 So now we do have this check in place, then I'll create a new variable, new quantity and this will be one 27 00:02:17,910 --> 00:02:22,760 by default and then I'll check if product is anything but undefined, 28 00:02:22,770 --> 00:02:27,930 so if we actually do have a valid product. If that is the case, I need to increase the quantity, 29 00:02:28,110 --> 00:02:37,260 so if we do have a product here, I now need to basically get my old quantity for this product and then 30 00:02:37,410 --> 00:02:38,670 change it. 31 00:02:38,670 --> 00:02:44,430 We'll do this later because right now we don't have any products in there so let's now only work on 32 00:02:44,430 --> 00:02:46,240 the new product case. 33 00:02:46,290 --> 00:02:50,910 So if we got no product here, we know this product is not part of the cart yet, 34 00:02:50,910 --> 00:02:58,850 so what I'll do at this point here is I will return a call to product find by ID because I need to find 35 00:02:58,850 --> 00:03:00,870 the general product data for this product 36 00:03:00,880 --> 00:03:07,140 now, for my prod ID it's not part of the cart but it's of course still in the database in the products 37 00:03:07,140 --> 00:03:15,670 table and here, I will have a nested then call because it makes things a bit easier here because I will 38 00:03:15,670 --> 00:03:19,490 execute two very different kinds of code for the case that 39 00:03:19,510 --> 00:03:23,970 we have an existing product in the cart or that we have to add a new one and therefore find it 40 00:03:23,970 --> 00:03:29,650 first of all. So here I know this is my product as it's stored in the products table and this is the product 41 00:03:29,650 --> 00:03:34,420 I want to add to my cart and this can now be done by returning 42 00:03:34,600 --> 00:03:36,380 and now I need to access my cart again. 43 00:03:36,400 --> 00:03:43,030 Now my cart is available here in this anonymous function but not in this one. To make it available 44 00:03:43,030 --> 00:03:50,200 down there too, I'll create a new cart to variable or fetch the cart maybe to not always rename, use the same 45 00:03:50,200 --> 00:03:50,940 name 46 00:03:51,130 --> 00:03:55,580 and then here I'll store the cart in fetched cart, 47 00:03:55,630 --> 00:04:02,770 so now it's not only available here but in this overall function here and therefore down there, I now have 48 00:04:02,770 --> 00:04:05,040 access to my fetched cart 49 00:04:05,050 --> 00:04:10,120 and on that fetched cart, I can call add product. 50 00:04:10,150 --> 00:04:15,060 It's another magic method added by sequelize for many to many relationships, 51 00:04:15,100 --> 00:04:20,890 I can add a single product here and I will add it to this in-between table with its ID. 52 00:04:21,310 --> 00:04:23,680 So here I add the product I retrieved, 53 00:04:23,680 --> 00:04:30,720 I just need to also make sure that I set this extra field I added to my cart item, this is the in-between 54 00:04:30,760 --> 00:04:31,330 table 55 00:04:31,390 --> 00:04:34,140 but for every entry, I also want to have quantity 56 00:04:34,570 --> 00:04:40,120 and if I have more than just two matching IDs, I need to tell sequelize that there is an extra field 57 00:04:40,240 --> 00:04:41,450 that needs to be set 58 00:04:41,770 --> 00:04:49,590 and I do this by passing an object to add product as the second argument and there I'll add through, 59 00:04:49,930 --> 00:04:52,150 you might remember through from app.js, 60 00:04:52,180 --> 00:04:58,880 there we use that to tell sequelize which model to use as the in between model and therefore as the in-between 61 00:04:58,960 --> 00:05:00,040 table, 62 00:05:00,040 --> 00:05:04,510 now I'm telling sequelize, well for that in-between table, 63 00:05:04,630 --> 00:05:07,960 here's some additional information you need to set the values in there, 64 00:05:08,140 --> 00:05:13,660 so that's another object and there I'm basically setting the keys or the fields that should be set in 65 00:05:13,660 --> 00:05:15,510 the in-between table, in this case 66 00:05:15,520 --> 00:05:21,080 it's the quantity field which should be set to new quantity. 67 00:05:21,550 --> 00:05:26,530 So this is the case that I add a new product for the first time, new quantity will be one here and I'm 68 00:05:26,530 --> 00:05:28,750 storing the product with that quantity. 69 00:05:29,110 --> 00:05:30,320 Let's see if that works, 70 00:05:30,340 --> 00:05:33,160 if I save this and I go to products, 71 00:05:33,320 --> 00:05:34,170 got no products so 72 00:05:34,180 --> 00:05:38,450 let's quickly add one, just with some dummy data to speed this up. 73 00:05:38,610 --> 00:05:42,140 If I go to products and I click add to cart, 74 00:05:42,360 --> 00:05:45,020 we're not redirecting which is why we're stuck on this page 75 00:05:45,090 --> 00:05:46,740 but we got no error here 76 00:05:46,740 --> 00:05:54,870 by the looks of it and if we refresh or load cart items, we see a new product was added or a new element 77 00:05:54,870 --> 00:06:02,050 was added to the cart with quantity one pointing at that cart with ID 1 and the product with ID 1, 78 00:06:02,070 --> 00:06:04,920 so this seems to work. 79 00:06:05,070 --> 00:06:14,100 Now let's just make sure we also well do see our carts page, so here I'll add a then block where I simply call 80 00:06:14,100 --> 00:06:18,330 res redirect/cart. 81 00:06:18,380 --> 00:06:20,250 So let's try this again now 82 00:06:23,650 --> 00:06:27,710 and now I get an error on that cart page and that is what I mentioned before, 83 00:06:27,770 --> 00:06:29,210 this will now break. 84 00:06:29,210 --> 00:06:35,440 So before we handle the case that we add a product to the cart which is already in the cart and therefore 85 00:06:35,480 --> 00:06:37,060 increase its quantity, 86 00:06:37,070 --> 00:06:40,350 let's make sure we can see the cart items on this page again.