WEBVTT 00:05.200 --> 00:06.790 Hi everyone welcome back. 00:07.040 --> 00:11.370 So in this video we're going to start to build the back API that we talked about. 00:11.450 --> 00:12.050 OK. 00:12.050 --> 00:19.160 So I made a new folder called Banky ions and deep games and I went into it I opened a new terminal and 00:19.160 --> 00:20.680 I'm in it inside of it. 00:20.710 --> 00:23.160 You're going to start building the pride from scratch. 00:23.390 --> 00:23.720 OK. 00:23.720 --> 00:25.470 So what what do we usually do. 00:25.480 --> 00:32.780 Well you start with a docker composed file case or what I do not touch daquiri compose dykey and then 00:32.780 --> 00:34.420 we're going to do two directories. 00:34.490 --> 00:38.870 Make directory web and make directory. 00:39.140 --> 00:51.820 Then again I and the doc files some Livesay touch web slash docker file them and to also touch divi 00:51.880 --> 00:53.920 slash knocker file. 00:54.340 --> 00:55.610 OK. 00:56.470 --> 00:57.160 All right. 00:57.160 --> 00:59.880 So inside webs are going to do is. 00:59.970 --> 01:07.060 I have a couple of things that my application which is apt up is somewhat a touch at duppy wide. 01:07.180 --> 01:09.290 I also have my requirements dot decks. 01:09.380 --> 01:13.780 So I'm doing touch requirements text. 01:14.390 --> 01:20.070 All right so I have my structure now I'm going to go out sites and then I'm going to do Suda at home. 01:20.230 --> 01:20.720 OK. 01:20.790 --> 01:23.420 So almost in the end folder 01:28.140 --> 01:30.240 or write so we have a folder here. 01:30.330 --> 01:33.670 So let's start with the compost file as usual. 01:33.960 --> 01:40.770 So we're going to write as you do version and then three and then we're going to have two services. 01:40.770 --> 01:45.180 We're going to have the Web and we're going to have D-B again. 01:45.270 --> 01:46.990 So for Abebe It's simple. 01:47.010 --> 01:51.320 We're going to build it from not slash TV. 01:51.720 --> 02:04.450 So the docker file and the for when I'm going to build it from dot slash web and I'm going to open it 02:04.450 --> 02:05.140 on board. 02:05.140 --> 02:13.630 So when I connect some boards and is going to be 5000 to 5000 right then I'm going to link it so links 02:14.480 --> 02:16.490 and I'm going to add D-B into that link. 02:16.500 --> 02:16.870 OK. 02:16.900 --> 02:21.230 So I want to link it into the service D-B so that they're linked together. 02:21.550 --> 02:24.520 OK so that's it for the block recomposing I'm always the same. 02:24.520 --> 02:25.610 Very simple. 02:25.980 --> 02:29.190 OK so let's go to the docker file of D-B. 02:29.350 --> 02:36.260 OK so there should be only one line which is from Mongo then 3.6 point for it and redone. 02:36.460 --> 02:41.410 So if you're using any other and there's a newer version of Mongo and you want to use it then feel free 02:41.410 --> 02:43.190 to just update this number. 02:43.210 --> 02:47.550 The API is usually or usually is the same regardless. 02:47.560 --> 02:48.440 OK. 02:48.940 --> 02:53.850 All right so now we have the docker file for the need for the application. 02:53.860 --> 02:59.640 So first of all we need bison because this is flask and classes from bison. 02:59.650 --> 03:08.230 So from bison 3 and then we're going to do work directory and slash user slash source slash app and 03:08.230 --> 03:16.630 then we're going to copy the requirements dot text requirements that text into dot slash to induce slash 03:16.630 --> 03:26.810 user slash slash output and then we're going to do a run chip install and then no cache directory Nashar 03:26.930 --> 03:30.870 and then requirements die dx. 03:30.970 --> 03:31.900 OK. 03:32.320 --> 03:33.030 All right. 03:33.130 --> 03:41.340 So the finals are two files things we need to copy all this folder to our Web applications or do copy 03:41.350 --> 03:42.340 dot dot. 03:42.460 --> 03:49.090 So we're going to copy this folder over here Web into slush use your slush or slush out and then the 03:49.090 --> 03:51.880 final thing is what we want to run up. 03:51.900 --> 03:58.640 So I want to do CMT and then Piscean and then add up the way. 03:58.700 --> 03:59.480 Right. 03:59.680 --> 04:00.480 And that should be it. 04:00.490 --> 04:03.020 So your save that and redone. 04:03.250 --> 04:10.120 Now what about the requirements well for this route we won't need any fancy or fancy requirements really. 04:10.180 --> 04:13.840 So I just need a flask and each flask restful. 04:13.900 --> 04:14.670 All right. 04:14.920 --> 04:19.610 So flask rest for I need time mango to communicate with. 04:19.870 --> 04:23.860 The bean and I need be Crypta for the password hashing. 04:23.860 --> 04:24.840 All right. 04:24.880 --> 04:32.140 And that's it only for libraries and we're done with building the architecture if you may say of the 04:32.140 --> 04:34.610 software or of the API. 04:34.830 --> 04:35.350 OK. 04:35.380 --> 04:38.760 So the next step that we want to do is to start implementing. 04:38.830 --> 04:42.340 So let's start implementing for example the registration. 04:42.750 --> 04:43.390 All right. 04:43.480 --> 04:49.290 So first of all we're going to import some libraries and some manuals some constructors and so on. 04:49.300 --> 04:56.050 So first of all we're going to import flump flask import the flask constructor Giese identify which 04:56.050 --> 05:01.250 is a super useful function that we always use and request to get the posted data. 05:01.540 --> 05:08.420 We're also going to import from flask restful and want to import AAPI. 05:08.530 --> 05:12.350 So how do you define this as an API and resource. 05:12.460 --> 05:16.180 Since I always inherit from it when I divide the classes. 05:16.180 --> 05:19.620 Next I'm going to import from PI Mongo. 05:19.810 --> 05:26.860 I want to import Mongo client and remember that M is capital and the C is capital and then I'm going 05:26.860 --> 05:28.560 to import secret. 05:28.910 --> 05:32.890 OK because I want to hash my password and that's it. 05:32.890 --> 05:40.960 Next I'm going to initialize my applications only as a app is equal to Flast constructor and that underscore 05:40.960 --> 05:43.390 underscore name and a square inch square gate. 05:43.450 --> 05:45.890 So that's usually main. 05:45.910 --> 05:52.720 Next I'm going to do an API and when I get initialized this apt to be an API I want to see API constructor 05:52.730 --> 05:54.260 off app. 05:54.640 --> 06:01.230 Right now the next step that we need to do is to connect to the byme up to the Mago DBI database writes 06:01.230 --> 06:03.870 on going to a client. 06:03.880 --> 06:07.940 First of all the client is equal to Mongo client. 06:08.710 --> 06:11.000 And then I'm going to write Mongo D-B. 06:11.000 --> 06:13.100 So let's see if I can zoom that in. 06:13.180 --> 06:16.690 Mongered Eby semi-colon slash slash. 06:16.690 --> 06:21.190 And then we're gonna say D-B dot 2 7 0 1 7. 06:21.190 --> 06:27.850 OK so that's the default point that Mago DBI runs on and D-B is that you are ELF from the dock or compose. 06:27.850 --> 06:29.360 Right so this is D-B. 06:29.470 --> 06:32.020 It means refer to this container over here. 06:32.230 --> 06:33.390 All right. 06:33.490 --> 06:35.580 OK cool. 06:35.680 --> 06:43.240 After we've connected our client we need to find a new database to say Give me is equal to client dot 06:43.510 --> 06:50.610 and then let's just say it banca API again so I'm going to define a new database called Mahnke API. 06:51.100 --> 06:53.950 Next I'm going to do a new collection called users. 06:53.980 --> 06:56.790 So I'm going to say users is equal to a. 06:56.830 --> 07:01.190 And then users inside a get go. 07:01.320 --> 07:06.580 Now let's first write a few helper functions that we might need in the registration function. 07:06.600 --> 07:12.720 So one of them that we always usually use is the user exists and one or I define user exist. 07:13.290 --> 07:14.020 OK. 07:14.190 --> 07:20.250 And then he's got eclipse exists and I gothic in a username and we're going that the way we're going 07:20.250 --> 07:25.280 to check a user exists is we're going to see if the users not find. 07:25.530 --> 07:31.330 And then I want to find some username with the one in the function parameter. 07:31.560 --> 07:37.600 So if I find that the count of such records is equal to zero then I return false. 07:37.650 --> 07:41.670 Right because this user name doesn't exist. 07:41.670 --> 07:42.390 So I work. 07:42.420 --> 07:45.930 So the answer to user exists is false. 07:45.930 --> 07:50.770 Else return true because the user does exist. 07:50.790 --> 07:53.990 If this count is not zero so it's greater than zero. 07:54.120 --> 07:57.040 Then this user exists and I should return true. 07:57.810 --> 08:03.060 All right so I'm done with the user exists now the next thing we need to do is to implement the registration 08:03.060 --> 08:03.520 class. 08:03.530 --> 08:10.920 I'm going to write a class register and then resource what I inherit from resource that I'm not into 08:10.980 --> 08:18.000 since all of these resources are remember all of them are post post post post but post some undefine. 08:18.020 --> 08:20.070 Post self. 08:20.760 --> 08:27.780 And then inside that the first step is usually to get the posted data right so posted data is equal 08:27.780 --> 08:28.840 to your request. 08:28.850 --> 08:30.600 DOD get underscore. 08:30.720 --> 08:32.270 Jason. 08:33.280 --> 08:44.790 OK after that I'm gonna get the username and password so username is equal to posted data username and 08:44.790 --> 08:46.410 password. 08:46.860 --> 08:51.780 You two posted data password. 08:51.880 --> 08:54.460 Alright ok cool. 08:54.570 --> 09:01.840 Now the next thing we're going to do is to check if the user exists so if user exist. 09:02.190 --> 09:06.290 So if user exists with this username. 09:06.630 --> 09:16.810 So if the user exists then I can't allow the user to or to to log in right because that would be. 09:17.040 --> 09:22.920 I can't have two usernames with the same user in two users with the same usernames so I won't allow 09:22.920 --> 09:28.970 that so I'm going to say returned Jason or return map isn't equal to the. 09:29.740 --> 09:32.670 Return map is equal to status is 3 or 1. 09:32.670 --> 09:35.880 Because it's an invalid username 3 or 1. 09:36.450 --> 09:43.110 And for the message I'm going to write invalid username invalid username and then I'm just going to 09:43.110 --> 09:45.260 return Jaysh on the fly. 09:45.940 --> 09:48.160 The return Jasen OK. 09:48.960 --> 09:49.410 All right. 09:49.420 --> 09:52.640 So this user doesn't exist on the other hand. 09:52.740 --> 10:02.510 Then I need to hash passwords I want to say hashed password is equal to the script so we grabbed the 10:02.610 --> 10:10.570 hash password that I'm on right password but don't forget to encode it as UTF 8. 10:10.700 --> 10:13.210 So when I asked UTF 8. 10:13.740 --> 10:20.530 And then when I write the script it generates salt and generates old function. 10:20.940 --> 10:23.800 Ok so now I've had my function. 10:23.940 --> 10:25.740 So what's the next thing to do. 10:25.830 --> 10:32.220 Well I need to store the user name and password into the database of my users. 10:32.580 --> 10:37.570 So his last password of course not the normal backstrap password. 10:37.650 --> 10:40.550 So many new users Doug answered. 10:40.810 --> 10:45.270 Ok then I inserted the user with this username. 10:45.300 --> 10:47.290 The one that was posted to me. 10:47.580 --> 10:55.710 I'm going to set put a user with the hashed password so hashed underscore which is hashed and the score 10:55.710 --> 10:56.990 password. 10:57.240 --> 11:02.460 And I'm going to put 2 extra Ifill's I want to put for each of the users. 11:02.550 --> 11:09.830 Can has 0 1 and get OK. 11:10.790 --> 11:14.180 So 0 in is how much money does he own. 11:14.190 --> 11:19.140 For example in your bank account you might own $1000 or $2000. 11:19.140 --> 11:26.470 So how much money does this person own and how much debt to the bank does this person own. 11:26.550 --> 11:29.120 So how many low how much loans has he taken. 11:29.280 --> 11:29.810 OK. 11:29.910 --> 11:34.650 So when you open an account you usually don't have anything in that country you have $0 and you have 11:34.650 --> 11:35.330 zero debt. 11:35.370 --> 11:36.050 Good. 11:36.390 --> 11:38.990 So we're going to start the user from scratch. 11:39.060 --> 11:40.110 OK. 11:40.650 --> 11:47.070 Now the second thing that we need to do is to return to reply the user that hey you successfully signed 11:47.070 --> 11:48.300 up for the API. 11:48.330 --> 11:48.900 Right. 11:48.900 --> 11:54.490 So going to see your return Jaison is equal to status is 200. 11:54.810 --> 12:02.850 And then for the message I'm going to return something along the line off use successfully signed of 12:02.870 --> 12:04.260 course the API. 12:04.260 --> 12:05.210 OK. 12:05.820 --> 12:07.120 And then just returned. 12:07.170 --> 12:17.760 Jason if I engage in a game and we're done we should be done with the registration class and that's 12:17.760 --> 12:18.140 it. 12:18.180 --> 12:18.890 OK. 12:19.110 --> 12:24.760 So the next class that we need to implement is going to be the class. 12:24.850 --> 12:25.380 Let's see. 12:25.420 --> 12:29.380 So we should probably implement that transfer class right. 12:29.520 --> 12:31.650 So let's see how we can implement that. 12:31.660 --> 12:32.110 OK. 12:32.250 --> 12:38.340 So first of all we need to implement a few helper functions that we're going to be using later on in 12:38.340 --> 12:44.820 the transfer and all the other classes really which are just so we can you know we don't have to reuse 12:44.820 --> 12:46.790 code or copy and paste code. 12:46.800 --> 12:52.560 So are you going to define functions that do the useful operations for us so you can just finish them 12:52.560 --> 12:53.610 in one line of code. 12:53.610 --> 12:54.220 OK. 12:54.690 --> 12:59.640 So the first helper function that we're going to use is the verify password function of an array and 12:59.910 --> 13:08.930 define verify password that is Gothika username and password and either going to return true or false. 13:09.240 --> 13:12.990 It returns true if the password is. 13:13.210 --> 13:18.620 This password matches this username and it returns false otherwise. 13:19.230 --> 13:19.770 All right. 13:19.800 --> 13:21.210 So let's get started. 13:21.210 --> 13:25.220 So first of all I need to make sure that this username exists in my database right. 13:25.230 --> 13:29.900 Because if he doesn't then this username definitely doesn't match this password. 13:30.090 --> 13:30.340 OK. 13:30.360 --> 13:37.500 So the first thing I do is check if not user exists with this username. 13:37.770 --> 13:40.230 Then just return false. 13:40.340 --> 13:46.940 Ok this user this password does not match this username otherwise is this user exists. 13:46.980 --> 13:49.780 So now I need to retrieve his hashed password. 13:49.930 --> 13:55.460 I'm going to get hashed password is equal to users that find. 13:55.620 --> 13:56.320 OK. 13:56.540 --> 14:02.990 And then I find the username user with this user name here that was posted. 14:03.690 --> 14:05.640 And I want to access the first one. 14:05.640 --> 14:08.090 There's only one user with this user name. 14:08.250 --> 14:16.410 And I want to get his password field so his hashed password the one I stored and then I'm going to see 14:16.500 --> 14:17.890 if be crypt. 14:17.970 --> 14:28.550 So if the crypt does Tasche password and then password does encode UTF 8. 14:29.210 --> 14:29.890 OK. 14:30.190 --> 14:37.260 And then hashed password is equal to the hashtag password. 14:37.360 --> 14:39.300 Then in that case I return true. 14:39.400 --> 14:45.210 Yes this password matches they use any else return false. 14:45.220 --> 14:46.730 This is incorrect right. 14:46.840 --> 14:53.820 So this this password does not match this using it because their hatches the hash is don't match. 14:53.980 --> 14:54.690 OK. 14:54.850 --> 14:58.590 And that's it for the function so the verify passwords on you. 14:58.840 --> 15:04.210 Now another function that might be useful is if I want to know how much cash this user has. 15:04.210 --> 15:06.750 How much does he own then. 15:06.820 --> 15:09.230 I should only do it whether it just won't go to a function. 15:09.250 --> 15:09.820 Right. 15:10.000 --> 15:18.640 So when I do define cash with user OK with this username and I want to know how much cash or how much 15:18.640 --> 15:19.940 does he owe you money. 15:19.960 --> 15:20.540 OK. 15:20.650 --> 15:28.540 So when I say cash is equal to users so just users does find that I'm going to find the user with this 15:28.540 --> 15:36.820 user name and I'm going to access the zero user because there's only one with this username and I'm 15:36.820 --> 15:41.390 going to get on because if you remember what he owns is in the field own. 15:41.570 --> 15:43.350 And I'm when to return cash. 15:43.450 --> 15:46.370 OK so that's how much the user owns. 15:46.510 --> 15:52.680 Now another function that we might of course need is to know how much debt does it does this user our. 15:52.770 --> 15:54.760 So why don't you find another function. 15:54.770 --> 16:03.200 Def define debt with a user with this username and I want to get the debt that he has. 16:03.210 --> 16:12.670 So what is a debt is equal to users defined gay and then the user name is going to be username and then 16:12.670 --> 16:18.030 I'm going to access the first user and I'm going to get the amount of debt that he has. 16:18.190 --> 16:18.860 OK. 16:19.000 --> 16:20.830 And then I just returned dead. 16:21.250 --> 16:26.640 So all these functions of course I'm using them with the assumption that this username exists. 16:26.650 --> 16:31.210 Now if you want to add some extra checks you're free to do so of course. 16:31.410 --> 16:32.320 OK. 16:32.850 --> 16:33.870 Now what else. 16:34.000 --> 16:40.270 Well we've got another function that we've been using in previous videos instead of just doing a return 16:40.270 --> 16:46.840 Jay Sawney calls to this and then filling it in every single time that we actually meet a function that 16:46.840 --> 16:50.000 generates this return dictionary automatically. 16:50.020 --> 16:51.880 So let's do it do this function again. 16:51.880 --> 16:58.710 So I want to do define generate a return dictionary. 16:58.980 --> 17:01.250 OK then I'm going to have a status. 17:01.380 --> 17:02.840 And then I have a message. 17:02.860 --> 17:03.430 OK. 17:03.700 --> 17:06.540 And then what does this function is going to do. 17:06.640 --> 17:16.080 It's going to go return Jaison is equal to its status is status message is the message. 17:16.540 --> 17:19.780 And I'm just going to return return they said. 17:19.900 --> 17:21.440 And that's basically the function. 17:21.460 --> 17:24.210 That's all it does. 17:24.430 --> 17:25.040 All right then. 17:25.050 --> 17:27.000 So far so cool. 17:27.130 --> 17:28.770 Now what else do we need. 17:28.930 --> 17:30.890 Well we need a couple of things oles. 17:31.060 --> 17:35.080 We also need a function that verifies credentials of a user. 17:35.110 --> 17:35.600 Right. 17:35.680 --> 17:45.340 So we need to check whether some user is in inputted the correct username and password or not. 17:45.340 --> 17:52.710 But then this function is not only going to return the this this password is correct. 17:52.750 --> 17:53.640 True or false. 17:53.710 --> 17:57.080 But it's also going to return the error that we should return. 17:57.190 --> 17:57.930 OK. 17:58.000 --> 18:01.260 So I'm going to define a function defined are you going to see what I mean by that. 18:01.270 --> 18:03.800 In a few seconds to define verify. 18:04.120 --> 18:12.100 OK so there's very psi credentials with username and password. 18:12.730 --> 18:13.480 OK. 18:13.720 --> 18:18.820 And then I want to say if not user exist user name. 18:18.820 --> 18:23.320 So this function is going to return to things like say this user doesn't exist. 18:23.320 --> 18:25.380 I'm going to return first of all. 18:25.400 --> 18:31.510 So this function to me at the conference here is going to add you're going to return a tuple. 18:31.570 --> 18:36.720 The first part of the tuple is going to be an error. 18:37.220 --> 18:38.890 Now dictionary. 18:38.920 --> 18:39.480 OK. 18:39.510 --> 18:41.380 It is going to be a dictionary with the error. 18:41.380 --> 18:44.600 So for example status three or three message. 18:44.640 --> 18:45.320 Blah blah blah. 18:45.340 --> 18:46.120 OK. 18:46.360 --> 18:51.490 And then the second part of that is going to be true or false. 18:51.580 --> 18:55.710 So this one is going to tell me whether there's an error or not in the credentials. 18:55.720 --> 18:59.240 So true means this user name and password there is a problem. 18:59.410 --> 19:02.390 And the problem is described in this ere dictionary. 19:03.130 --> 19:06.040 But if this is false then that means there is no problems. 19:06.040 --> 19:10.200 And then this dictionary is just none or no or whatever. 19:10.360 --> 19:11.240 OK. 19:11.470 --> 19:14.960 So if the user doesn't exist then I'm going to retire and do things. 19:14.980 --> 19:15.530 OK. 19:15.610 --> 19:18.490 I need to return the generator. 19:18.550 --> 19:25.570 So I'm going to generate dictionary with the air three or one I'm going to tell them invalid username 19:27.580 --> 19:30.200 but I'm also going to read you something else which is true. 19:30.250 --> 19:32.020 So I tell them hey there is an air. 19:32.040 --> 19:33.470 So take care. 19:33.940 --> 19:34.650 OK. 19:34.870 --> 19:37.410 Now I'm going to say correct password. 19:37.420 --> 19:40.050 So what is the correct password of this user. 19:40.180 --> 19:45.430 Well I'm going to say all correct answer is basically a bully and says not tell me whether this password 19:45.430 --> 19:46.680 is correct or not. 19:46.690 --> 19:49.400 So let me use the function that we are in the road here. 19:49.630 --> 19:57.670 Verify and P.W. is going to write verify that with you with this username and this password. 19:57.900 --> 20:04.790 Ok now I'm going to check it's not the correct answer is the password is not correct. 20:04.900 --> 20:12.460 Now I'm going to read Tyrian generate riparian dictionaries on one or turn it and an error dictionary 20:12.550 --> 20:20.830 of three or two which is an incorrect in correct password. 20:20.830 --> 20:22.340 And I'm also going to return true. 20:22.360 --> 20:23.980 So that means I'm returning some. 20:23.970 --> 20:25.440 There is a problem. 20:25.930 --> 20:33.550 However if I pass these do tests and everything is fine then I just return non and false. 20:33.550 --> 20:39.420 So there is no errors and the error dictionary is none because there is no errors right. 20:39.950 --> 20:40.470 OK. 20:40.530 --> 20:46.300 So now a couple of functions that were and it was done with the helper functions and we're not going 20:46.300 --> 20:51.030 to write any help or functions from now on it's gonna to be strictly classes. 20:51.130 --> 20:57.070 So the last two is we are going to write two functions to update the account to update the balance of 20:57.100 --> 21:01.360 what a user owns and what that debt off a user. 21:01.360 --> 21:07.270 OK so we're going to update our update account from to update what the user owns or when I write an 21:07.270 --> 21:11.260 update debt account to update how much debt the user has. 21:11.260 --> 21:11.930 OK. 21:12.280 --> 21:15.780 So the first one is define update account. 21:16.070 --> 21:16.810 OK. 21:16.960 --> 21:21.840 That takes in that username and then a balance and then it needs to update. 21:21.880 --> 21:24.180 What this user owns to the balance. 21:24.310 --> 21:26.900 So when do users update. 21:27.100 --> 21:27.780 OK. 21:28.300 --> 21:34.180 And then user name is username and that what I want update it with. 21:34.180 --> 21:43.900 So I'm going to do a comma and then set and that is that year I want to change his what he owns into 21:43.900 --> 21:44.790 the new balance. 21:44.800 --> 21:45.850 Okay. 21:46.540 --> 21:48.010 And then that's it. 21:48.010 --> 21:50.360 So that's what all the functions. 21:50.740 --> 21:54.420 Now the same thing goes for update debt. 21:54.540 --> 21:57.760 OK so that's a new function with user name and balance. 21:58.020 --> 22:01.460 And I need to update his debt to be this new balance. 22:01.760 --> 22:04.340 Do users update. 22:04.480 --> 22:05.290 Okay. 22:05.780 --> 22:11.690 And then I'm going to choose the correct user. 22:12.910 --> 22:20.020 Without you Capital your posts so use your name and then for a year I'm going to sit through things 22:20.030 --> 22:23.520 I'm going to do a dollar set and I'm going to change his debt. 22:23.650 --> 22:26.260 So the debt is going to be the new balance. 22:26.260 --> 22:27.130 All right. 22:27.310 --> 22:33.070 So now we finally finished the helper functions and now let's finally finally finally right. 22:33.070 --> 22:37.820 The class ad and you're going to see why these helper functions are very useful. 22:37.960 --> 22:46.180 Ok so now I want to write a classical ad which allows me to add a couple of some money into my accounts 22:46.250 --> 22:46.810 own. 22:46.870 --> 22:47.640 OK. 22:47.940 --> 22:50.430 So then a new class added resource. 22:50.780 --> 22:58.190 And then when I do define post self and then first of all I want I need to get the posted data. 22:58.230 --> 23:02.340 I get it from request that I get underscore Jason. 23:02.530 --> 23:03.240 OK. 23:03.550 --> 23:17.360 Next I get username is equal to post a data username password is equal to the posted data password. 23:17.560 --> 23:18.520 All right. 23:19.030 --> 23:25.090 Then we do also want the money right how much money you want to add to the bank account so money you 23:25.080 --> 23:27.980 go to post a data money. 23:28.120 --> 23:29.280 OK. 23:29.620 --> 23:30.580 All right. 23:30.850 --> 23:33.560 Or amounts listless change that to amount to great. 23:33.580 --> 23:36.640 So it makes more sense. 23:36.640 --> 23:39.690 All right so the first thing is we need to verify the credentials. 23:39.850 --> 23:45.850 So I'm going to use this function here which is the verify credentials and it returns two things the 23:45.850 --> 23:48.510 dictionary and the true or false. 23:48.520 --> 23:49.290 OK. 23:49.720 --> 23:51.370 Whether there is an error or not. 23:51.580 --> 24:01.590 So when I say returned Jason and error is equal to verify credentials with this user name and password. 24:01.690 --> 24:02.820 OK. 24:03.340 --> 24:04.710 Now if error. 24:05.020 --> 24:11.530 So there is an error if this is true then I'm just going to return this on if I return Jason I'm going 24:11.530 --> 24:14.850 to return that Garrett or whatever it is in this dictionary Okay. 24:15.010 --> 24:15.590 And I'm done. 24:15.640 --> 24:18.340 Just a line of go see how useful this is. 24:18.880 --> 24:19.460 OK. 24:19.540 --> 24:23.450 Another thing is I want to check if the money is less than or equal to zero. 24:23.530 --> 24:27.560 So I'm going to see if money is less than or equal to zero. 24:27.850 --> 24:28.980 Then what do I do. 24:29.200 --> 24:36.610 Well I need to return to justify and then generate return dictionary. 24:36.790 --> 24:42.700 I'm going to wager and there are three or four if you remember from here three or four is if the amount 24:42.700 --> 24:49.630 of money is less than or equal to zero or here okay three or four of them on our return three or four 24:49.870 --> 24:59.080 and then I'm going to also say let's say the money amount entered must be greater than zero. 24:59.100 --> 25:01.550 Okay great then year. 25:02.380 --> 25:08.620 And that's it in case we see how this this is very useful or you're turning all these errors checks 25:08.650 --> 25:09.880 into just one line. 25:09.880 --> 25:11.580 So that's pretty useful. 25:12.100 --> 25:15.180 OK so the money is not less than or equal to zero. 25:15.220 --> 25:20.650 So if the money is greater than zero then first of all I want to know how much cash does this user have. 25:20.940 --> 25:27.880 I say cash is equal to cash with the user with this username. 25:27.880 --> 25:32.620 Now the second thing is I want to add I want to have an account for the bank right. 25:32.630 --> 25:33.850 Is your member here. 25:34.030 --> 25:35.790 I have an account for the bank. 25:35.880 --> 25:40.400 And so I need to give the bank some money for this transaction right. 25:40.420 --> 25:44.220 Or you can think of it as money for using this service. 25:44.230 --> 25:50.800 So in fact what I'm going to do is for every transaction I'm going to take only $1 from the users and 25:50.800 --> 25:53.080 put it and give it to my bank account. 25:53.110 --> 25:54.110 OK. 25:54.130 --> 26:03.140 So I'm going to do see money minus the school wants someone to take away one for myself and give the 26:03.140 --> 26:04.870 remaining to the user. 26:04.880 --> 26:10.340 OK so I'm going to take away one from one from the money and then I'm going to check how much does the 26:10.340 --> 26:11.000 bank have. 26:11.000 --> 26:14.360 So bank cash is equal to cash with the user. 26:14.420 --> 26:16.510 And then I'm going to call the bank a bank. 26:16.510 --> 26:18.310 Great with the all caps. 26:18.350 --> 26:26.270 So this is I want to know how much of that the bank has and then I'm I do update account or I want to 26:26.270 --> 26:31.020 update the bank with the bank cash. 26:31.100 --> 26:40.340 So his previous balance that he had that the bank had plus one because I stick in one dollar as a transaction 26:40.340 --> 26:41.940 fee. 26:41.940 --> 26:43.690 Next I'm going to update. 26:43.730 --> 26:48.420 So I want to update the remaining amount of money to the user. 26:48.470 --> 26:50.870 So I'm going to do update account 26:53.270 --> 26:56.280 to the user with the user name. 26:56.390 --> 26:58.930 OK so no not none. 26:59.080 --> 27:04.130 And so just the user with this username and then I'm going to add cash plus money. 27:04.130 --> 27:04.720 OK. 27:04.910 --> 27:09.070 So it's the cash plus the money minus one day that we took away on. 27:09.140 --> 27:12.410 So the previous cash that he had plus the money and then he just added. 27:12.410 --> 27:16.760 So this is his new balance or her new balance rate. 27:17.180 --> 27:25.490 And then once I'm done with that then I just simply return on if I generate to return dictionary of 27:25.850 --> 27:26.430 200. 27:26.420 --> 27:33.650 So success and amount added successfully to the account. 27:33.680 --> 27:34.110 OK. 27:34.160 --> 27:35.880 So that's our message. 27:35.930 --> 27:38.370 And we were done with the add function. 27:38.450 --> 27:42.690 So you can see why these functions were very very very helpful. 27:42.740 --> 27:48.850 They just allow us to write this very concisely and all the logic is actually in here. 27:49.120 --> 27:49.770 OK. 27:50.000 --> 27:55.790 So we're going to stop here so we've written basically two to two of them sort of written register here 27:55.980 --> 27:58.630 and change the color or not. 27:58.910 --> 28:02.750 OK let's change the color to have written this register here. 28:02.750 --> 28:06.110 So this is a check and then were also written this ad over here. 28:06.110 --> 28:13.920 So this is also a check very bad check but so we do have or we still have transfer. 28:13.940 --> 28:15.860 We still have to check balance. 28:15.860 --> 28:20.810 We still have dayglo and we still have been able to do these ones in the next few years we're going 28:20.810 --> 28:23.410 to pause here and pick up in the next video. 28:23.420 --> 28:24.450 So yeah. 28:24.650 --> 28:26.390 So until the next video happy curbing.