1 00:00:00,775 --> 00:00:02,491 - [Instructor] Hi and welcome back to the course. 2 00:00:02,491 --> 00:00:07,212 In this video we would like to implement the put endpoint. 3 00:00:07,212 --> 00:00:09,513 But unfortunately there is something that 4 00:00:09,513 --> 00:00:12,624 we have to do before we can do that. 5 00:00:12,624 --> 00:00:15,296 Notice how the put endpoint also has a line 6 00:00:15,296 --> 00:00:19,709 items dot append because this used to append the new 7 00:00:19,709 --> 00:00:22,716 item to the items list, or update an item 8 00:00:22,716 --> 00:00:25,403 if it was already there. 9 00:00:25,403 --> 00:00:28,998 There is an items dot append here, but we don't have 10 00:00:28,998 --> 00:00:33,499 a way to add an item to the database right now. 11 00:00:33,499 --> 00:00:35,582 We do have a post method. 12 00:00:38,532 --> 00:00:41,049 The post method does create an item and 13 00:00:41,049 --> 00:00:43,021 put it in the database. 14 00:00:43,021 --> 00:00:47,128 However, there is no way for the put method 15 00:00:47,128 --> 00:00:50,933 to call the post method unless it also wants 16 00:00:50,933 --> 00:00:55,146 to do things like return the item on the status code 17 00:00:55,146 --> 00:00:58,113 and check that the items are already there. 18 00:00:58,113 --> 00:01:00,215 What we're going to do, is we're going to once again 19 00:01:00,215 --> 00:01:03,632 extract this here into a separate method. 20 00:01:05,133 --> 00:01:08,853 Extract the insertion of items onto a separate method. 21 00:01:08,853 --> 00:01:13,037 I'm going to cut that out and then create another 22 00:01:13,037 --> 00:01:16,370 class method which I'm gonna call insert 23 00:01:18,332 --> 00:01:23,287 and it's going to take in an item actually not a name. 24 00:01:23,287 --> 00:01:25,923 The item that it takes in is then used to get a 25 00:01:25,923 --> 00:01:28,379 name and a price and then that's inserted 26 00:01:28,379 --> 00:01:29,879 into the database. 27 00:01:31,395 --> 00:01:36,282 The way we call this is by doing self dot insert item. 28 00:01:36,282 --> 00:01:38,284 The item is this piece of chasing here, 29 00:01:38,284 --> 00:01:40,117 this dictionary there. 30 00:01:41,832 --> 00:01:44,514 Hopefully that makes sense. 31 00:01:44,514 --> 00:01:48,014 Do remember that there might be a problem. 32 00:01:49,095 --> 00:01:54,002 The database may fail to insert the item for example. 33 00:01:54,002 --> 00:01:57,051 If that does happen there is a specific construct 34 00:01:57,051 --> 00:02:00,905 that python has that is to deal with exceptions. 35 00:02:00,905 --> 00:02:04,322 An exception is what python runs whenever 36 00:02:05,173 --> 00:02:06,506 an error occurs. 37 00:02:07,655 --> 00:02:11,488 We can try self dot insert, accept, exception. 38 00:02:15,440 --> 00:02:16,912 Actually we don't need that. 39 00:02:16,912 --> 00:02:21,079 Except only and then return message an error occurred 40 00:02:23,986 --> 00:02:25,986 with two r's, inserting. 41 00:02:28,927 --> 00:02:32,747 Let me explain what's happening here. 42 00:02:32,747 --> 00:02:35,938 This really is as logical as it seems. 43 00:02:35,938 --> 00:02:38,707 The first thing we do is we try to do something. 44 00:02:38,707 --> 00:02:42,849 We try to run the self dot insert method. 45 00:02:42,849 --> 00:02:47,477 The except block only runs if there was an error. 46 00:02:47,477 --> 00:02:49,144 An exception raised. 47 00:02:50,702 --> 00:02:53,640 The cursor for example may raise an exception 48 00:02:53,640 --> 00:02:57,958 if it cannot insert the item into the database. 49 00:02:57,958 --> 00:03:00,542 The commit may raise an exception if the connection 50 00:03:00,542 --> 00:03:03,041 gets closed prematurely. 51 00:03:03,041 --> 00:03:05,035 There's a few things that could go wrong 52 00:03:05,035 --> 00:03:06,956 and here all that we're doing is we're saying, 53 00:03:06,956 --> 00:03:09,649 we're gonna try to insert the item in and if we 54 00:03:09,649 --> 00:03:11,970 fail for any reason we're just going to return 55 00:03:11,970 --> 00:03:15,508 a message saying an error occurred. 56 00:03:15,508 --> 00:03:17,585 It's not something we've done before but it makes 57 00:03:17,585 --> 00:03:19,699 sense to be able to do that. 58 00:03:19,699 --> 00:03:24,346 You can also apply this to any other part of your code. 59 00:03:24,346 --> 00:03:27,400 For example up here in the get. 60 00:03:27,400 --> 00:03:30,212 The find by name may also fail prematurely. 61 00:03:30,212 --> 00:03:34,311 You may also want to round up with a try accept block 62 00:03:34,311 --> 00:03:36,163 given an appropriate error message 63 00:03:36,163 --> 00:03:38,417 if it fails to find something. 64 00:03:38,417 --> 00:03:39,753 Sorry, not if it fails to find something, 65 00:03:39,753 --> 00:03:42,253 if it fails to run the search. 66 00:03:43,209 --> 00:03:45,044 Remember if it fails to find something, 67 00:03:45,044 --> 00:03:48,293 we're already saying not found. 68 00:03:48,293 --> 00:03:50,926 Also something to remember, if an error occurs 69 00:03:50,926 --> 00:03:53,351 inserting the item, that's not the 70 00:03:53,351 --> 00:03:57,018 requester's fault and it's certainly not OK. 71 00:03:58,524 --> 00:04:02,085 We don't want to return 200, 200 is the default. 72 00:04:02,085 --> 00:04:03,401 We do not want to do that. 73 00:04:03,401 --> 00:04:07,063 What we want to return is 500 internal server error. 74 00:04:07,063 --> 00:04:09,082 That's what that means. 75 00:04:09,082 --> 00:04:10,915 Internal server error. 76 00:04:13,081 --> 00:04:14,588 That just means something went wrong 77 00:04:14,588 --> 00:04:16,481 and we can't tell you exactly what. 78 00:04:16,481 --> 00:04:21,095 But something went wrong and it's not your fault. 79 00:04:21,095 --> 00:04:23,416 Do remember that it's very important 80 00:04:23,416 --> 00:04:28,001 you are returning 400 when something did go wrong 81 00:04:28,001 --> 00:04:31,204 with the request, and 500 when something didn't 82 00:04:31,204 --> 00:04:34,705 go wrong with the request but the server messed up 83 00:04:34,705 --> 00:04:37,574 so that the user knows they didn't do anything wrong 84 00:04:37,574 --> 00:04:40,907 it's just the server that had a problem. 85 00:04:42,904 --> 00:04:44,158 That's everything for this video. 86 00:04:44,158 --> 00:04:46,632 We've covered the try accept block that's really 87 00:04:46,632 --> 00:04:49,644 useful in python and also we've extracted 88 00:04:49,644 --> 00:04:53,392 the insert method out and we're gonna be able to 89 00:04:53,392 --> 00:04:56,642 write the put method in the next video. 90 00:04:58,044 --> 00:05:00,356 Thanks for joining me and I'll see you there.