WEBVTT 00:05.340 --> 00:06.940 Everyone welcome back. 00:06.950 --> 00:13.910 So in this second part the last part of this video we're going to be implementing the last three resources 00:14.360 --> 00:20.840 which are subtract multiply and divide it now subtract multiply are very similar to. 00:20.890 --> 00:24.620 And in fact the only difference there are very few differences. 00:24.680 --> 00:31.380 But if you remember that divide we discussed at that great divide we should be careful about that there's 00:31.400 --> 00:36.370 an extra layer of code which is three hundred and two which is when y is zero. 00:36.530 --> 00:38.720 We have to be a bit careful here. 00:38.720 --> 00:43.900 When when when we're doing when we're doing the checking for it. 00:44.280 --> 00:44.650 OK. 00:44.660 --> 00:48.830 So let's go back to our app here. 00:48.890 --> 00:49.430 OK. 00:49.520 --> 00:52.510 So let's start implementing subtract. 00:52.730 --> 00:59.030 Well we don't have to really you know usually we don't like to copy code and we can we can you know 00:59.060 --> 01:01.540 instead do this process much much easier. 01:01.550 --> 01:10.310 But for now was just copy the code and see how we would change that to suit our need here in this case. 01:10.310 --> 01:12.100 Let's start with the premise. 01:12.240 --> 01:15.040 Ok so you do this and then paste it. 01:15.310 --> 01:15.930 OK. 01:16.100 --> 01:25.730 So if I'm here then the resource subtract Shipley's and we should replace this one with subtract was 01:25.730 --> 01:31.510 requested using the method post and then the step one is to get the posted to. 01:32.040 --> 01:37.390 Step 1 be to verify the validity of the posted data. 01:37.400 --> 01:39.510 So let's go back to the validity data. 01:39.520 --> 01:45.270 But this time we're going to be passing this conscience contract because we're in the subtract resource 01:45.370 --> 01:46.930 not the and resource. 01:46.940 --> 01:49.220 So let's go back and see. 01:49.610 --> 01:50.630 Whoops. 01:50.660 --> 01:56.180 So right so we need to I think we need to do. 01:56.410 --> 01:59.790 So let's give me a second here. 02:00.200 --> 02:08.790 So pseudo atom right this atom needs to be in Suder. 02:08.900 --> 02:09.890 We're developing it 02:13.510 --> 02:18.100 OK so let's first case is going to happen to them. 02:18.370 --> 02:25.690 Let's first copy the code from the other one because we can't even accept unless we're in Suta right. 02:25.720 --> 02:34.000 So we're gonna copy this code here and then we're going to switch to the other one here. 02:34.810 --> 02:42.180 And then you just paste everything and say you should take with no problem let's close this one. 02:42.190 --> 02:48.970 This one is without pseudo axes don't save and then OK let's let's keep going here. 02:48.970 --> 02:52.110 So it's just a pseudo problem it's nothing too serious. 02:52.180 --> 02:56.590 So we're going to have you Gotcha the posted data for the track method. 02:56.650 --> 03:01.300 So let's go back and see how the subject method is used. 03:01.300 --> 03:08.020 So if you go back here and then which you check the posted data if the function name is that then we 03:08.020 --> 03:11.750 have to check if x is not in the posted data or Y. 03:12.070 --> 03:16.860 But actually this is the same conditions that we're checking for in these Tracht functions. 03:16.870 --> 03:23.070 If we look here subtract function has exactly the same error code status codes 200 and 300 and they're 03:23.080 --> 03:29.320 exactly relating to the same exact missing parameters or OK's. 03:29.320 --> 03:31.360 Or you're missing parameters are OK. 03:31.390 --> 03:39.570 So in fact we can we couldn't really avoid writing this whole thing again if we just say four function 03:40.690 --> 03:47.580 is equal to subtract that is tracked and then that's it. 03:47.570 --> 03:54.180 If x is not in there then we return 3 0 1 code to indicate a missing parameter. 03:55.240 --> 03:59.330 And if this is all everything's fine then returned 200. 03:59.750 --> 04:00.130 OK. 04:00.130 --> 04:06.370 So let's go back to our subtract resource now once we've made sure the status code is the status quo 04:06.420 --> 04:08.880 is not 200 meaning is 300. 04:09.010 --> 04:12.240 Hear them return message and there happened. 04:12.280 --> 04:15.990 And where we turned the state code we got from the Hanshin. 04:16.090 --> 04:19.250 Next we would get the value of x y. 04:19.390 --> 04:29.140 Change it to an integer and then we would do X minus Y's here and b subtract the posted data and then 04:29.180 --> 04:35.490 return map as a message returned and status code 200. 04:35.620 --> 04:38.160 So the message we're getting traction. 04:38.390 --> 04:41.980 Man is and the state has good success. 04:42.220 --> 04:44.640 Finally let's go to the ER. 04:44.650 --> 04:49.840 Finally please let's do the same thing for us. 04:50.350 --> 04:52.600 So let's do the same thing for multiply. 04:52.600 --> 04:54.960 Let's copy this code every year. 05:02.840 --> 05:08.310 Embraced it here and then and so this resource is now multiply. 05:08.480 --> 05:15.090 Now if you go back to multiply this here we see it's also two hundred and three oh wow. 05:15.140 --> 05:16.580 So what was your place. 05:16.590 --> 05:18.380 Two hundred three answers. 05:18.380 --> 05:18.910 Two hundred. 05:18.920 --> 05:19.400 OK. 05:19.500 --> 05:21.640 Three are One missing parameter. 05:21.800 --> 05:28.950 So we're going to do first get the posted data then we're going to check the validity of this in that 05:29.020 --> 05:31.100 show posted data and that's it. 05:31.190 --> 05:33.760 But then we have to account for the function. 05:33.890 --> 05:40.980 So instead of subtract is going to be multiply your hopes as is the substract one. 05:41.030 --> 05:43.880 So it's going to be a multiply one here 05:48.860 --> 05:59.150 and then we got caucuses and then we're going to check here in the check posted function or the function 05:59.150 --> 06:03.980 name is equal to multiply. 06:04.070 --> 06:08.550 Then we do that again the same check check if X or Y are not there. 06:08.600 --> 06:10.640 Else return 200. 06:11.350 --> 06:20.360 OK so now we go here and then instead of subtraction multiplication multiply and then return map is 06:20.360 --> 06:21.940 equal to this. 06:21.950 --> 06:27.560 Now you can notice here that the only difference we're doing is we're doing this tracked here and this 06:27.560 --> 06:29.700 multiply here so you can actually do. 06:29.900 --> 06:31.840 You can be a bit smarter about this. 06:31.840 --> 06:38.720 You can do like a map and then for example map every name with a function to an operator to perform 06:38.780 --> 06:39.380 a function. 06:39.380 --> 06:39.650 Right. 06:39.680 --> 06:42.920 To perform the operator here. 06:43.040 --> 06:46.540 But you know let's let's just go for the minimum viable product right. 06:46.550 --> 06:52.790 Let's just go for the most you know worst code we can write just to make sure it's working and to get 06:52.850 --> 06:59.930 the idea of the whole workflow and how things really work and usually things you know resources are 07:00.080 --> 07:06.220 very that related if they're related then we usually encapsulate them all in one class. 07:06.500 --> 07:11.840 So don't worry about the the the copy pasting for now. 07:11.930 --> 07:14.990 Usually we don't really copy paste the code. 07:15.230 --> 07:21.320 I think I said this should be so tracked because this is the subtract method. 07:21.800 --> 07:22.820 And the other one. 07:22.820 --> 07:26.450 And again this is just the problems of copy pasting code. 07:26.450 --> 07:31.200 That's why we usually copy paste code that you know. 07:31.280 --> 07:36.280 Let's let's just focus on the ideas for now and later on we need to optimize this. 07:36.710 --> 07:42.870 OK so once we have multiplication The last thing to do is to check for division and division. 07:42.870 --> 07:44.610 Isn't that a bit different. 07:44.620 --> 07:45.060 Right. 07:45.140 --> 07:48.380 Let's copy this one last time. 07:52.610 --> 07:55.450 And then paste it here. 07:55.550 --> 07:59.890 Are we going to finally resource divide. 07:59.960 --> 08:05.410 We're going to get decent data and we're going to pass it as we're in the subject the posted data in 08:05.450 --> 08:07.420 case of the division. 08:07.940 --> 08:11.570 And then Les mentioned let's just fix the function here first. 08:11.630 --> 08:17.630 Once we get to see this code we're going to return an error if there's any errors whether it's 3 1 or 08:17.630 --> 08:18.390 3 2. 08:18.410 --> 08:25.390 So here we have 3 1 and 3 2 3 or 1 is missing parameter 3 and 2 is why was zero. 08:25.400 --> 08:28.080 So we can't divide by zero. 08:29.360 --> 08:37.850 So we get X Y and then the response is X Y and return the response and then we can do this. 08:38.270 --> 08:44.020 Since this is my this this is an integer and this is an integer so which do times one point. 08:44.970 --> 08:51.950 It was done on point out over why just to make sure that it's a float. 08:51.950 --> 08:54.930 And then we turned the response back. 08:55.160 --> 08:55.840 OK. 08:55.910 --> 09:05.220 So let's go now that she posted Daytona function and then this one here is going to have two cases or 09:05.300 --> 09:11.300 else is a function name whose 09:13.940 --> 09:18.480 name is equal to division. 09:18.890 --> 09:19.160 Right. 09:19.160 --> 09:22.250 That's what you called it from here. 09:22.540 --> 09:22.880 Yes. 09:22.880 --> 09:24.000 Division. 09:24.720 --> 09:27.910 Let's make sure we spell that correctly. 09:28.460 --> 09:30.690 So is the function name is division. 09:30.740 --> 09:32.840 We're going to check for two codes right. 09:32.940 --> 09:39.520 If so the first one is if x not in Kostin data. 09:40.040 --> 09:45.590 Or why not in person. 09:46.560 --> 09:51.560 Then we simply return three or what else. 09:51.890 --> 10:03.330 Yes or Ellis is host and data why is equal to zero. 10:03.720 --> 10:06.230 In that case we're would return 3 0 2. 10:06.450 --> 10:10.200 Because that was cast into an integer. 10:10.200 --> 10:13.170 Make sure everything's fine. 10:13.280 --> 10:22.220 So if integer is zero then you tend to go to else where we turn 200. 10:22.230 --> 10:26.050 So success. 10:26.370 --> 10:34.050 OK so we have here 3 1 denoting that one of the parameters was not there 3 or 2 meaning why was zero 10:34.290 --> 10:37.170 or 200 which is a success. 10:37.170 --> 10:41.460 So now we really finished building the API or the resources. 10:41.550 --> 10:45.000 Now the only thing left is to add these resources here right. 10:45.010 --> 10:47.700 So so far we haven't added it to our API. 10:47.710 --> 10:57.860 So there's one last step which is to add the resources and then add subtract to slash unless you get 10:57.900 --> 11:13.110 our API was slash subtract slash subtract should do AP either and resource multiply and slash multiply. 11:13.550 --> 11:16.560 And finally API and resource 11:19.620 --> 11:26.420 divide divide and slash division right. 11:26.660 --> 11:30.250 And now with initial basically build our API. 11:30.420 --> 11:41.520 So let's start testing lets make sure that lets try first exporting flask code to and up P-ROC flask 11:42.320 --> 11:46.040 this flask from a flask. 11:46.610 --> 11:49.830 Okay OK so I've done as else if. 11:49.840 --> 11:50.130 Right. 11:50.200 --> 11:53.770 This it's that's in C++ 9. 11:54.020 --> 11:59.580 So it's l s l f this. 12:00.160 --> 12:00.640 OK. 12:00.780 --> 12:02.660 Let's see if we have any other problems. 12:02.730 --> 12:03.910 And we don't. 12:04.410 --> 12:09.660 OK so let's now open post them and try and test our application. 12:09.660 --> 12:12.020 Make sure everything's working fine. 12:24.910 --> 12:32.690 OK so once we have once we have an open can go to slash multiply Let's try multiply first. 12:33.430 --> 12:45.260 And then in the row data with us and x 10 and y 12 to that should return us 120. 12:45.430 --> 12:56.650 So let's put this year and send the request and we get indeed Under-20 is the message and 200 is escrowed. 12:56.680 --> 12:58.590 Now let's try. 12:59.020 --> 13:01.600 Tracked 10 and 12. 13:01.600 --> 13:06.470 That should give us negative 2 so negative 2 and their sponsors do. 13:06.820 --> 13:08.340 Now let's check divide. 13:08.380 --> 13:08.930 Right. 13:09.130 --> 13:11.190 So that's one divide. 13:11.190 --> 13:13.660 For example 10 by 5. 13:14.330 --> 13:16.930 When we said that we have an error. 13:16.960 --> 13:19.020 Let's check the air first here. 13:19.360 --> 13:21.710 So it says here that 0. 13:21.820 --> 13:25.900 So I I my routed to the wrong place. 13:25.900 --> 13:26.790 OK. 13:27.290 --> 13:27.620 Good. 13:27.650 --> 13:28.100 Yeah. 13:28.300 --> 13:34.300 So it's slash divisions if you look at last year it tells me post-blast divide four or four. 13:34.300 --> 13:36.150 It doesn't Nowhere's less divide. 13:36.160 --> 13:38.640 So it should be slash division. 13:38.770 --> 13:45.420 So let's change that to slash division and then send the request and we get the response to. 13:45.460 --> 13:45.700 Right. 13:45.700 --> 13:48.180 This is the response 10 to about it. 13:48.190 --> 13:51.820 My 5 is 2 and the status goes 200. 13:51.820 --> 13:57.150 Now what happens if it's 10 divided by three and it should be three points or anything. 13:57.150 --> 13:57.890 So these are three. 13:57.890 --> 14:01.660 And so what about if we put 8 or 0. 14:01.660 --> 14:04.470 Now that's that's what we should have cared about. 14:04.480 --> 14:05.590 Right. 14:05.650 --> 14:11.010 So once we have that we get this message and there have been statis go to 302. 14:11.020 --> 14:13.960 So our checking worked. 14:14.290 --> 14:16.430 What if we don't have one of the parameters 14:19.390 --> 14:24.280 and then well that one should should have must check are posted. 14:24.290 --> 14:25.590 Message me me me 14:38.920 --> 14:43.880 OK so I think the problem was to come over here that we should delete this summer. 14:43.970 --> 14:50.800 So let's try again in the GSA and then we get it on the air happens 3 or 1 which means there is a missing 14:53.110 --> 14:55.060 parameter in the sense data. 14:55.540 --> 14:59.670 So we now have a fully working API that is documented. 14:59.710 --> 15:02.420 You can easily change this. 15:03.100 --> 15:09.500 This diagram over here to the documentation for the user to see. 15:09.670 --> 15:14.860 Usually you can use something like swagger which is an online Web site to help you write the documentation 15:14.860 --> 15:15.540 for the API. 15:15.550 --> 15:22.120 But yeah we now have a working API that supports four functions and subtract divide and multiply with 15:22.150 --> 15:29.860 error checking we're returning correct responses to the users and it won't crash on any given input. 15:29.860 --> 15:36.760 Now of course you could argue that you know I can crash it of course if if if I give my application 15:36.760 --> 15:42.020 something like you know X as you know ABC. 15:42.060 --> 15:42.320 Right. 15:42.350 --> 15:46.610 And instead of a number you can be in a string right. 15:46.960 --> 15:50.170 Or for example why five right. 15:50.190 --> 15:51.030 So what would happen. 15:51.030 --> 15:54.870 Of course it would crash the you know an internal server. 15:54.880 --> 15:55.680 Right. 15:55.720 --> 16:01.030 So you know it's up to you for how much validation you want to do you know. 16:01.030 --> 16:06.880 Are you trusting that the user always send x and y are you trusting that the user assigned always x 16:06.880 --> 16:10.870 and y but are the always numbers or are they always in the years. 16:11.050 --> 16:13.000 Are they always not strings. 16:13.000 --> 16:18.340 You know you have to know this function could really you could spend a lot of time on just to make sure 16:18.340 --> 16:21.560 that nothing basically crashes your server. 16:21.640 --> 16:25.430 For example here you get a value error invalid literal for it. 16:25.570 --> 16:26.130 Right. 16:26.170 --> 16:28.220 Because a b c is not integer. 16:28.360 --> 16:37.060 So it's really up to you to to to to you know work on this error checking point here and make your error 16:37.060 --> 16:43.390 codes very very specific to the user and make sure what you can assume and what you can't assume on 16:43.390 --> 16:44.030 the data. 16:44.080 --> 16:49.660 But it's generally better if you you know anticipate everything can't trust that the user will always 16:49.660 --> 16:53.610 send you good information or are valid parameters. 16:53.620 --> 16:55.410 You have to always check it internally. 16:55.410 --> 16:58.170 Don't let anything crash your server. 16:58.220 --> 17:03.080 So that's basically the bare minimum in this for this API. 17:03.200 --> 17:05.030 And yeah I'll see you in the next video. 17:05.080 --> 17:06.500 So until that happens Tony.