1 00:00:05,040 --> 00:00:09,690 Alright, so let's look now at finishing the code for our simple jukebox. We've got 2 00:00:09,690 --> 00:00:13,590 our program printing the list of albums, and getting a choice from the user. The 3 00:00:13,590 --> 00:00:17,220 next bit of code will be very similar. It's going to display the songs for the 4 00:00:17,220 --> 00:00:22,380 selected album and let the user choose one. So looking at our albums data, 5 00:00:22,380 --> 00:00:27,880 in nested_data.py, the title of each song appears at index position 1. 6 00:00:27,880 --> 00:00:32,000 The track number, as you can see, is at position 0 and the title 7 00:00:32,000 --> 00:00:36,300 at position 1. Rather than having to remember that, when writing the code, 8 00:00:36,300 --> 00:00:41,260 let's create another constant in jukebox_menu.py. 9 00:00:41,260 --> 00:00:48,860 We'll add it below the existing one - we'll call this one SONG_TITLE_INDEX 10 00:00:48,860 --> 00:00:51,580 and we're setting it to the value of one. 11 00:00:51,590 --> 00:00:55,760 We don't need line 17 onwards. We just added those lines to see how we were 12 00:00:55,760 --> 00:01:00,340 indexing into the albums, to get the song lists. So I'm going to delete those 13 00:01:00,340 --> 00:01:04,540 and then replace that code, and the code we're going to add is going to display 14 00:01:04,549 --> 00:01:09,560 the list of songs. So I'm going to start with a print: print parentheses double 15 00:01:09,560 --> 00:01:16,759 quotes Please choose your song and a colon, closing double quote and right 16 00:01:16,759 --> 00:01:20,930 parenthesis, and notice that error there. I was a bit careless and wasn't paying 17 00:01:20,930 --> 00:01:27,260 attention. I need to tab this to the right indentation level, for this to work. 18 00:01:27,260 --> 00:01:31,220 But it's a good idea, just to make sure that you are indenting to the level 19 00:01:31,220 --> 00:01:37,720 appropriate to the code you're adding. Alright, also continuing on, for index comma then 20 00:01:37,720 --> 00:01:41,500 in parentheses - hopefully, by now, you know why we using parentheses - 21 00:01:41,500 --> 00:01:50,700 track_number comma song in enumerate parentheses songs_list 22 00:01:50,700 --> 00:01:55,240 right parenthesis and a colon. Then we'll get to the actual printing - print 23 00:01:55,240 --> 00:01:59,740 on the next line, parentheses double quotes and two replacement fields here, 24 00:01:59,740 --> 00:02:05,120 so left and right curly braces, colon space, another set of left and right curly braces 25 00:02:05,120 --> 00:02:08,320 double quote, and because it'll all fit on the same line, I won't go to the nextline 26 00:02:08,320 --> 00:02:14,360 with the dot format, parentheses index + 1 comma song 27 00:02:14,360 --> 00:02:18,940 and the two closing right parentheses. Alright, so having done that, 28 00:02:18,940 --> 00:02:23,690 and again, we're putting parentheses around track number and song, because 29 00:02:23,690 --> 00:02:27,290 these are the values that are being unpacked from the tuple, as we saw in an 30 00:02:27,290 --> 00:02:32,100 earlier video. Alright, next we need to get the user's song choice and print the title. 31 00:02:32,100 --> 00:02:36,500 So make a bit of space up here, and at the same indentation level as the 32 00:02:36,500 --> 00:02:41,620 for loop, I'm going to type song_choice is equal to int 33 00:02:41,620 --> 00:02:45,290 parenthesis input, left and right parentheses and then a closing right 34 00:02:45,290 --> 00:02:55,480 parenthesis. Then we'll test this, so if 1 is less than equal to song_choice 35 00:02:55,480 --> 00:03:02,520 less than equal to len parentheses songs_list 36 00:03:02,520 --> 00:03:09,140 right parentheses : Then we'll type title, on the next line, is equal to songs_list 37 00:03:09,140 --> 00:03:12,340 left and right square brackets, and within the first set of square brackets, 38 00:03:12,340 --> 00:03:19,140 song_choice - 1, then a second set of square brackets. 39 00:03:19,140 --> 00:03:22,300 And we need to choose the song index, so that's using our constant, 40 00:03:22,300 --> 00:03:26,880 song_title_index, and we'll put an 41 00:03:26,880 --> 00:03:35,520 else in under the if : and break. Alright, so once again, we've got two levels of 42 00:03:35,520 --> 00:03:40,709 indexing on line 23. We get the song tuple from songs list, using the user's 43 00:03:40,709 --> 00:03:45,480 choice as the index. We have to subtract 1, because indexes are zero-based, 44 00:03:45,480 --> 00:03:50,300 and the user's choice starts at 1. To get the second item from the tuple, we use our 45 00:03:50,300 --> 00:03:55,380 SONG_TITLE_INDEX constant. The name of the song is the second item, 46 00:03:55,380 --> 00:04:02,920 which is at position 1, and if you recall, we set our constant value on line 4 to 1. 47 00:04:02,920 --> 00:04:04,500 So before we run the program, we really 48 00:04:04,500 --> 00:04:08,880 should print out the chosen song, to make sure we got the right one, so let's do that. 49 00:04:08,880 --> 00:04:12,560 So indenting's at the same level as the if and the else. I'm going to type 50 00:04:12,560 --> 00:04:18,760 print parentheses, Playing, left and right curly braces for our replacement field, 51 00:04:18,760 --> 00:04:23,600 double quotes dot format parentheses title. On the next line, 52 00:04:23,600 --> 00:04:29,080 print parentheses double quotes equal sign, then outside of the double quote, 53 00:04:29,080 --> 00:04:34,320 x 40 and a right parenthesis. So in addition to the title that we're 54 00:04:34,320 --> 00:04:38,440 printing on line 27, I'm also printing a row of equal symbols, 55 00:04:38,440 --> 00:04:45,440 just to make the output a bit clearer. Time now to test the code. So I'm gonna run the program. 56 00:04:45,440 --> 00:04:48,940 Alright, clicking into the run window, I'm going to select option 3 - 57 00:04:48,940 --> 00:04:53,560 Nightflight. That's printed the songs from the Nightflight album, which is correct. 58 00:04:53,560 --> 00:04:59,540 I'm going to choose option 4, here, to print the song title, She used me up, and you 59 00:04:59,540 --> 00:05:03,400 can see that the program reports that it's playing She used me up, then the loop goes 60 00:05:03,400 --> 00:05:08,060 around again, ready for the next choice. So test the program thoroughly, to make 61 00:05:08,060 --> 00:05:13,080 sure valid options display the correct list of songs, and the correct song. 62 00:05:13,080 --> 00:05:17,120 At the moment, though, we don't have a lot of data. Because of that, I'd check every 63 00:05:17,130 --> 00:05:20,669 single option to make sure the results are correct. Also, make sure that an 64 00:05:20,669 --> 00:05:25,050 invalid option correctly exits the program, and that should happen when 65 00:05:25,050 --> 00:05:29,460 you're displaying the list of albums and also when a song list is being displayed. 66 00:05:29,460 --> 00:05:32,940 So moving on, the next video will be a challenge, and I'll go over my solution 67 00:05:32,940 --> 00:05:38,479 to that challenge, in the video after that one. See you in the next video.