WEBVTT 1 00:00:01.430 --> 00:00:02.860 Hi Guys, and welcome back. 2 00:00:02.860 --> 00:00:06.080 In this video, we're going to be creating the user menu 3 00:00:06.080 --> 00:00:08.710 for our project so that we can start interacting 4 00:00:08.710 --> 00:00:12.500 with users and looking at what our programme is going to do. 5 00:00:12.500 --> 00:00:15.670 To create the project, I've gone ahead and made a folder. 6 00:00:15.670 --> 00:00:16.970 I've called it Prog diary. 7 00:00:16.970 --> 00:00:18.290 You can call it whatever you want. 8 00:00:18.290 --> 00:00:20.630 And I've opened that with Visual Studio code, 9 00:00:20.630 --> 00:00:24.160 in this case, you can use your editor of choice of course, 10 00:00:24.160 --> 00:00:27.600 in here, I'm going to create a file called app.py. 11 00:00:27.600 --> 00:00:30.320 This is normally the app I use to start a project 12 00:00:30.320 --> 00:00:33.623 it's gonna contain the main logic of our application. 13 00:00:36.590 --> 00:00:38.200 Now that I've got this file here, 14 00:00:38.200 --> 00:00:41.560 we're going to start off by creating the main variable 15 00:00:41.560 --> 00:00:43.060 that is going to be the menu that 16 00:00:43.060 --> 00:00:44.763 we're going to show our users. 17 00:00:46.550 --> 00:00:48.360 So I've gone ahead and written that out, 18 00:00:48.360 --> 00:00:50.480 I've used the multi line string and we've got 19 00:00:50.480 --> 00:00:52.560 the Please select one of the following options, 20 00:00:52.560 --> 00:00:53.600 the three options, 21 00:00:53.600 --> 00:00:55.570 and then their selection with a space at the end 22 00:00:55.570 --> 00:00:58.690 so that users can go ahead and type after this. 23 00:00:58.690 --> 00:01:00.580 We're going to be passing this variable 24 00:01:00.580 --> 00:01:04.163 to the input function so that users can type what they want. 25 00:01:05.070 --> 00:01:06.580 As well as this variable, we're going to need 26 00:01:06.580 --> 00:01:08.920 some sort of welcome variable that we're going to show 27 00:01:08.920 --> 00:01:10.933 at the very start of our application. 28 00:01:14.350 --> 00:01:17.143 So here, I've created those two variables now, 29 00:01:18.620 --> 00:01:21.090 the next step is to have a loop 30 00:01:21.090 --> 00:01:23.840 that is going to run continuously asking the user 31 00:01:23.840 --> 00:01:25.940 what they want to do with our application 32 00:01:25.940 --> 00:01:28.470 until they enter the number three. 33 00:01:28.470 --> 00:01:31.070 So what we normally do when we want to do something 34 00:01:31.070 --> 00:01:33.950 like that is we use a while loop. 35 00:01:33.950 --> 00:01:36.450 So the first thing is to get the user input. 36 00:01:36.450 --> 00:01:39.680 And we're going to make that equal to the input of menu. 37 00:01:39.680 --> 00:01:42.940 So we're going to ask the user showing them this prompt, 38 00:01:42.940 --> 00:01:44.160 what they want to do, 39 00:01:44.160 --> 00:01:48.800 and while the user input is not equal to the number three, 40 00:01:48.800 --> 00:01:50.410 and remember that the input function 41 00:01:50.410 --> 00:01:51.780 always returns a string, 42 00:01:51.780 --> 00:01:55.580 so we need to compare against the number three as a string. 43 00:01:55.580 --> 00:01:57.610 Then we're going to run our menu 44 00:01:57.610 --> 00:01:58.970 we're gonna do here, 45 00:01:58.970 --> 00:02:00.540 whatever that the user wants to do. 46 00:02:00.540 --> 00:02:04.210 So we'll deal with user input here. 47 00:02:04.210 --> 00:02:08.070 Then at the end of the menu, we will ask the user again, 48 00:02:08.070 --> 00:02:10.780 we'll say user input equal input of menu. 49 00:02:10.780 --> 00:02:12.210 In just a moment, we're going to find 50 00:02:12.210 --> 00:02:14.310 a slightly better way of writing this menu 51 00:02:14.310 --> 00:02:16.820 so that we don't have this duplication. 52 00:02:16.820 --> 00:02:19.590 First of all, we ask the user for their choice. 53 00:02:19.590 --> 00:02:21.460 If it's not three, we start the loop, 54 00:02:21.460 --> 00:02:25.330 we do what they want us to do, be that one or two. 55 00:02:25.330 --> 00:02:27.090 And then we ask them again, 56 00:02:27.090 --> 00:02:28.050 when we ask them again, 57 00:02:28.050 --> 00:02:29.610 we go back to the top of the while loop, 58 00:02:29.610 --> 00:02:30.780 and we check again. 59 00:02:30.780 --> 00:02:32.080 And if it's not three, we run this again. 60 00:02:32.080 --> 00:02:34.233 And then we ask them again, and so on. 61 00:02:35.850 --> 00:02:38.530 To reduce duplication, we can use a new 62 00:02:38.530 --> 00:02:40.440 feature of Python 3.8. 63 00:02:40.440 --> 00:02:43.950 If you're using Python 3.8, that is the walrus operator 64 00:02:43.950 --> 00:02:46.290 or the assignment expression. 65 00:02:46.290 --> 00:02:48.070 The assignment expression allows us to put 66 00:02:48.070 --> 00:02:51.363 this input statement right in here, 67 00:02:53.100 --> 00:02:54.340 like that. 68 00:02:54.340 --> 00:02:57.560 And what this says is, while user input 69 00:02:57.560 --> 00:03:00.670 which should be equal to the input of menu 70 00:03:00.670 --> 00:03:05.220 is not equal to three, we will then run this code here. 71 00:03:05.220 --> 00:03:08.160 Now very important that the walrus operator or 72 00:03:08.160 --> 00:03:11.260 the assignment expression has lower precedence 73 00:03:11.260 --> 00:03:12.980 than the comparison. 74 00:03:12.980 --> 00:03:15.940 So when we write it like this, what we're actually 75 00:03:15.940 --> 00:03:19.070 doing is we're saying, while user input, 76 00:03:19.070 --> 00:03:22.430 which is equal to whether input of menu 77 00:03:22.430 --> 00:03:24.590 is not equal to three, 78 00:03:24.590 --> 00:03:26.030 and then we will run this code. 79 00:03:26.030 --> 00:03:27.390 So what this is really doing is, 80 00:03:27.390 --> 00:03:29.580 it's assigning two user input, 81 00:03:29.580 --> 00:03:32.190 whether the input of menu is not equal to three. 82 00:03:32.190 --> 00:03:34.930 So this will end up being true or false. 83 00:03:34.930 --> 00:03:38.620 It's not actually going to contain the content 84 00:03:38.620 --> 00:03:40.310 of what the user entered. 85 00:03:40.310 --> 00:03:43.270 So we have to put some brackets around it 86 00:03:43.270 --> 00:03:45.010 so that this evaluates first. 87 00:03:45.010 --> 00:03:47.350 And now this is what we wanted. 88 00:03:47.350 --> 00:03:52.350 We first give user input the value of calling input of menu. 89 00:03:52.800 --> 00:03:54.950 And then we compare that against three 90 00:03:54.950 --> 00:03:57.060 and we check that it's not equal to it. 91 00:03:57.060 --> 00:03:59.040 Now when we run this code here, 92 00:03:59.040 --> 00:04:02.460 the user input variable contains what the user typed. 93 00:04:02.460 --> 00:04:04.450 So that's what we wanted. 94 00:04:04.450 --> 00:04:06.770 So again, this is a new feature in python 3.8. 95 00:04:06.770 --> 00:04:09.380 If you're not using Python 3.8, you can use 96 00:04:09.380 --> 00:04:11.663 what we just typed a moment ago instead. 97 00:04:12.740 --> 00:04:15.510 So now that we've got our user input, we can go ahead 98 00:04:15.510 --> 00:04:18.950 and write a series of if statements that we can use 99 00:04:18.950 --> 00:04:21.010 to deal with a different options. 100 00:04:21.010 --> 00:04:25.217 So if the user input is equal to one, then we will add, 101 00:04:26.490 --> 00:04:27.800 so we'll say adding, 102 00:04:27.800 --> 00:04:29.510 and for now, I'm just gonna put this print statement. 103 00:04:29.510 --> 00:04:30.450 And here we're gonna add 104 00:04:30.450 --> 00:04:33.060 some more stuff to it in just a moment. 105 00:04:33.060 --> 00:04:36.490 Otherwise, if the user input is equal to two, 106 00:04:36.490 --> 00:04:38.510 then we're gonna print viewing. 107 00:04:38.510 --> 00:04:41.310 And again, later on, we're going to actually be displaying 108 00:04:41.310 --> 00:04:44.693 the the entries that they have in their entries list. 109 00:04:45.550 --> 00:04:49.240 Otherwise, if it's not one or two, 110 00:04:49.240 --> 00:04:50.150 but we know 111 00:04:50.150 --> 00:04:51.750 it's not three, because if it was three, 112 00:04:51.750 --> 00:04:54.160 we wouldn't be running this code to begin with. 113 00:04:54.160 --> 00:04:57.760 So otherwise, we know that it's not one, two or three, 114 00:04:57.760 --> 00:04:59.580 it must be something else that they've typed 115 00:04:59.580 --> 00:05:01.570 and that is an invalid option, so we're gonna 116 00:05:01.570 --> 00:05:04.843 tell them invalid option, please try again. 117 00:05:06.870 --> 00:05:09.570 So these are the three different branches 118 00:05:09.570 --> 00:05:10.870 of our if statement. 119 00:05:10.870 --> 00:05:12.790 And this is going to allow us to start 120 00:05:12.790 --> 00:05:16.650 thinking about our menu a bit better by seeing it in code. 121 00:05:16.650 --> 00:05:18.270 Of course, remember, we still have to use 122 00:05:18.270 --> 00:05:20.760 these welcome variable there to welcome users 123 00:05:20.760 --> 00:05:23.000 to our application, we're gonna print that at the top 124 00:05:23.000 --> 00:05:26.610 outside of the loop because we only want to print that once. 125 00:05:26.610 --> 00:05:29.790 And that's really our complete code for the user menu. 126 00:05:29.790 --> 00:05:31.640 Next up, we're gonna be adding functionality 127 00:05:31.640 --> 00:05:33.530 to keep track of entries. 128 00:05:33.530 --> 00:05:36.620 But we're not going to use a database just yet. 129 00:05:36.620 --> 00:05:40.090 We're going to add SQLite later on in this project. 130 00:05:40.090 --> 00:05:42.330 First, we're going to develop our programme logic 131 00:05:42.330 --> 00:05:46.740 by using a Python list as a simple database table, 132 00:05:46.740 --> 00:05:49.690 and then we're going to use SQLite later on. 133 00:05:49.690 --> 00:05:51.480 Using a list instead of a database 134 00:05:51.480 --> 00:05:53.870 allows us to quickly develop our programme 135 00:05:53.870 --> 00:05:56.450 without worrying about interacting 136 00:05:56.450 --> 00:05:58.400 with the database just yet. 137 00:05:58.400 --> 00:06:00.900 Once we're happy with all our functions, and how they work, 138 00:06:00.900 --> 00:06:03.160 we can read and write from the database 139 00:06:03.160 --> 00:06:04.640 instead of from the list. 140 00:06:04.640 --> 00:06:06.720 And changing that will be straightforward. 141 00:06:06.720 --> 00:06:08.130 And this way, we only have to worry 142 00:06:08.130 --> 00:06:12.090 about one aspect of software development at a time. 143 00:06:12.090 --> 00:06:13.370 All right, in the next video, we're going to 144 00:06:13.370 --> 00:06:16.060 look at what is SQL and then we're going to come back 145 00:06:16.060 --> 00:06:19.500 to this code and use Python lists as a database. 146 00:06:19.500 --> 00:06:21.103 I'll see you in the next one.