1 00:00:04,460 --> 00:00:07,510 Alright, so continuing on with our project. 2 00:00:07,510 --> 00:00:09,330 We're almost done at this point, 3 00:00:09,330 --> 00:00:12,730 but what if our data listBox isn't linked to another one? 4 00:00:12,730 --> 00:00:13,750 So we're going to need some way 5 00:00:13,750 --> 00:00:15,830 of linking two listBoxes together 6 00:00:15,830 --> 00:00:20,700 and this on_select method you can see here on line 59. 7 00:00:20,700 --> 00:00:22,410 Well, that should only try to requery 8 00:00:22,410 --> 00:00:24,930 another listBox if there actually is one. 9 00:00:24,930 --> 00:00:26,160 Now in a minute, what we're going to do 10 00:00:26,160 --> 00:00:28,250 is add another couple of fields to the class 11 00:00:28,250 --> 00:00:29,680 to handle the link. 12 00:00:29,680 --> 00:00:31,690 We're gonna finish off this method first, though. 13 00:00:31,690 --> 00:00:33,180 We're gonna get it to check 14 00:00:33,180 --> 00:00:34,910 that there is a link to this box 15 00:00:34,910 --> 00:00:39,020 before trying to requery one, so let's do that. 16 00:00:39,020 --> 00:00:41,270 We're going to put if self. 17 00:00:42,490 --> 00:00:45,660 so that's linked, and it's called box: 18 00:00:46,680 --> 00:00:49,110 we're gonna add that field shortly as I said, 19 00:00:49,110 --> 00:00:50,530 and then we're going to indent everything else. 20 00:00:50,530 --> 00:00:53,490 I'm gonna remove this extra commented out code now, 21 00:00:53,490 --> 00:00:55,650 which we no longer need. 22 00:00:55,650 --> 00:00:58,570 I'm also going to indent this code. 23 00:00:59,820 --> 00:01:03,630 And I'll just put another tab or space in there 24 00:01:03,630 --> 00:01:05,349 because IntelliJ was complaining 25 00:01:05,349 --> 00:01:08,850 that the hash was too close to the code, 26 00:01:08,850 --> 00:01:10,300 you need to put at least two spaces 27 00:01:10,300 --> 00:01:11,800 when you're actually adding a comment. 28 00:01:11,800 --> 00:01:13,550 So I've got rid of that warning. 29 00:01:13,550 --> 00:01:15,080 The other thing we're going to do here 30 00:01:15,080 --> 00:01:17,750 is change this albumList.requery, 31 00:01:17,750 --> 00:01:22,600 let's change that self.linked_box is what it should be. 32 00:01:22,600 --> 00:01:26,100 So that's self.linked_box.requery link id, 33 00:01:29,570 --> 00:01:32,650 so we haven't got the aristList hard coded anymore. 34 00:01:32,650 --> 00:01:34,980 So before we can see the new class working 35 00:01:34,980 --> 00:01:36,520 we need to add a way to link 36 00:01:36,520 --> 00:01:38,560 one data listBox to another. 37 00:01:38,560 --> 00:01:40,600 Now, not all listBoxes will be linked. 38 00:01:40,600 --> 00:01:43,300 Our songs list doesn't cause another box to be updated 39 00:01:43,300 --> 00:01:45,680 and we may want to use a single data listBox 40 00:01:45,680 --> 00:01:47,640 to display a database table 41 00:01:47,640 --> 00:01:50,120 without linking it to anything else. 42 00:01:50,120 --> 00:01:52,950 So rather than insisting that another data listBox 43 00:01:52,950 --> 00:01:55,450 is provided in the class init method, 44 00:01:55,450 --> 00:01:57,230 we're going to add a link method 45 00:01:57,230 --> 00:01:59,190 that can be used if required. 46 00:01:59,190 --> 00:02:00,630 Now we're going to use the link method 47 00:02:00,630 --> 00:02:03,650 by passing it a widget that we wanna link to 48 00:02:03,650 --> 00:02:06,250 and a database column that forms that link, 49 00:02:06,250 --> 00:02:07,580 and that means we're going to need 50 00:02:07,580 --> 00:02:10,449 another couple of data attributes in our class. 51 00:02:10,449 --> 00:02:13,680 Let's go back up to the top and add those data attributes, 52 00:02:13,680 --> 00:02:14,920 and we're going to put them just after 53 00:02:14,920 --> 00:02:17,760 the super call here in line 30. 54 00:02:17,760 --> 00:02:21,930 So first one, self. and it's going to be linked_box, 55 00:02:22,870 --> 00:02:25,290 we set that to none initially, 56 00:02:25,290 --> 00:02:27,950 and likewise for self.link_field 57 00:02:28,970 --> 00:02:30,490 we're going to set that to none, 58 00:02:30,490 --> 00:02:33,110 so that's our two attributes. 59 00:02:33,110 --> 00:02:34,410 And again, we're defaulting to none 60 00:02:34,410 --> 00:02:36,380 so that there's no link to start with. 61 00:02:36,380 --> 00:02:38,580 Now, if we need to link two listBoxes 62 00:02:38,580 --> 00:02:40,610 then we're going to call that link method, 63 00:02:40,610 --> 00:02:41,620 so let's add that method, 64 00:02:41,620 --> 00:02:45,780 and I'm gonna add that just after the clear method here, 65 00:02:46,800 --> 00:02:48,970 so it's gonna be def link, 66 00:02:50,420 --> 00:02:51,840 we've got self as an argument, 67 00:02:51,840 --> 00:02:53,670 , widget , link_field: 68 00:02:57,590 --> 00:03:01,760 and we're gonna put self.linked_box = widget 69 00:03:03,730 --> 00:03:07,140 and then we're gonna do widget.link_field 70 00:03:09,680 --> 00:03:12,100 gonna set that to link_field, 71 00:03:13,290 --> 00:03:14,980 so we're basically saving the value 72 00:03:14,980 --> 00:03:17,190 that was passed in the argument. 73 00:03:17,190 --> 00:03:18,540 So at this point whenever we want 74 00:03:18,540 --> 00:03:20,560 to link two listBoxes together, 75 00:03:20,560 --> 00:03:24,070 we can call this new link method of the master listBox, 76 00:03:24,070 --> 00:03:25,390 then we're passing in a reference 77 00:03:25,390 --> 00:03:27,590 to the data listBox that we wanna link to 78 00:03:27,590 --> 00:03:29,450 as well as the name of the column 79 00:03:29,450 --> 00:03:31,830 in the linked data listBoxes table. 80 00:03:31,830 --> 00:03:33,880 I'm gonna go through what this method's doing again 81 00:03:33,880 --> 00:03:35,570 once we've seen it working 82 00:03:35,570 --> 00:03:37,930 and can refer to the actual widgets. 83 00:03:37,930 --> 00:03:39,590 So that's fixed some of the warnings, 84 00:03:39,590 --> 00:03:41,780 if we have a look at our own query method, 85 00:03:41,780 --> 00:03:43,210 that's looking a lot better now, 86 00:03:43,210 --> 00:03:44,780 we fixed some of those warnings, 87 00:03:44,780 --> 00:03:46,920 but we've still got one more error to fix, 88 00:03:46,920 --> 00:03:48,040 so we come over here and have a look 89 00:03:48,040 --> 00:03:51,210 in our right margin and click on that, 90 00:03:52,070 --> 00:03:55,150 and you can see I've got a problem on line 115, 91 00:03:55,150 --> 00:03:56,480 and you can see with the code there 92 00:03:56,480 --> 00:03:59,200 that that's where we downed the listBox select event 93 00:03:59,200 --> 00:04:01,490 to the get_albums function. 94 00:04:01,490 --> 00:04:02,710 Now we've moved that function 95 00:04:02,710 --> 00:04:04,870 into the class and renamed it, 96 00:04:04,870 --> 00:04:07,090 which is why we're now, of course, getting that error. 97 00:04:07,090 --> 00:04:08,780 Now there's no reason why we have to perform 98 00:04:08,780 --> 00:04:10,450 the bind in the main programme. 99 00:04:10,450 --> 00:04:12,220 Our data listBox class knows 100 00:04:12,220 --> 00:04:13,620 that it's got a nonselect method, 101 00:04:13,620 --> 00:04:15,670 so we can bind to the method itself. 102 00:04:15,670 --> 00:04:19,670 So I'm gonna cut that line of code out, 103 00:04:19,670 --> 00:04:22,450 and I'm going to paste it to the data listBox init method, 104 00:04:22,450 --> 00:04:24,080 so I'm gonna go right up to the top, 105 00:04:24,080 --> 00:04:26,080 the init method up here, 106 00:04:27,410 --> 00:04:29,840 and I'm going to paste it after our data attributes 107 00:04:29,840 --> 00:04:32,140 before the sql select statement, 108 00:04:32,140 --> 00:04:33,620 paste it in there like that. 109 00:04:33,620 --> 00:04:37,800 Now we're no longer binding to the get_albums function 110 00:04:37,800 --> 00:04:40,660 so we have to change that in our on_select method, 111 00:04:40,660 --> 00:04:42,150 and we also wanna use self, though, 112 00:04:42,150 --> 00:04:44,920 instead of referring to the artistList widget, 113 00:04:44,920 --> 00:04:47,170 so I'm gonna change that to 114 00:04:48,630 --> 00:04:53,020 remove the artistList call there, that should be self.bind. 115 00:04:53,020 --> 00:04:54,710 The listBox select is still correct, 116 00:04:54,710 --> 00:04:57,640 but instead of the get_albums function 117 00:04:57,640 --> 00:05:00,230 it's going to be self, or method I should say, 118 00:05:00,230 --> 00:05:02,900 it's going to be self.on_select, 119 00:05:05,700 --> 00:05:07,250 and be careful when you're making that change 120 00:05:07,250 --> 00:05:10,670 because you can see here that IntelliJ tried to be helpful 121 00:05:10,670 --> 00:05:14,040 and added the parenthesis after the on_select. 122 00:05:14,040 --> 00:05:16,420 We actually don't want that, we wanna remove that, 123 00:05:16,420 --> 00:05:17,810 and again, the reason we're moving it is 124 00:05:17,810 --> 00:05:20,240 that if we left it with the parenthesis 125 00:05:20,240 --> 00:05:21,620 then that would result in binding 126 00:05:21,620 --> 00:05:23,510 to the result of calling the method 127 00:05:23,510 --> 00:05:25,360 and our method returns none in this case, 128 00:05:25,360 --> 00:05:26,960 which, by the way, is the default 129 00:05:26,960 --> 00:05:28,570 for all functions and methods 130 00:05:28,570 --> 00:05:30,950 if you don't explicitly return anything, 131 00:05:30,950 --> 00:05:32,620 and we wanna bind to the method, 132 00:05:32,620 --> 00:05:35,330 not to the value that calling it returns, 133 00:05:35,330 --> 00:05:36,310 so watch out for that. 134 00:05:36,310 --> 00:05:38,270 I'm saying, I know we've talked about that in the past, 135 00:05:38,270 --> 00:05:40,050 but it's a very easy mistake to make, 136 00:05:40,050 --> 00:05:41,780 especially with IntelliJ's, you know, 137 00:05:41,780 --> 00:05:43,920 quote unquote helpfulness here. 138 00:05:43,920 --> 00:05:44,810 Alright, so I fixed that, 139 00:05:44,810 --> 00:05:46,840 now I'm going to delete one of those lines 140 00:05:46,840 --> 00:05:48,990 to keep IntelliJ happy. 141 00:05:48,990 --> 00:05:52,390 Okay, so once our main code's created the albumList 142 00:05:52,390 --> 00:05:54,850 we can actually link it to the artistList, 143 00:05:54,850 --> 00:05:57,620 so let's go ahead and do that. 144 00:05:57,620 --> 00:05:59,620 We're gonna go down here 145 00:06:01,330 --> 00:06:04,300 and the moment we've got this albumList.bind 146 00:06:04,300 --> 00:06:08,470 to get_songs, so I'm actually gonna comment that out. 147 00:06:09,800 --> 00:06:10,930 What we're going to do instead 148 00:06:10,930 --> 00:06:12,930 is do an artistList.link 149 00:06:15,470 --> 00:06:18,670 and it's going to be to albumList, 150 00:06:18,670 --> 00:06:20,840 and then the field artist. 151 00:06:22,940 --> 00:06:24,490 Moving down we can do the same 152 00:06:24,490 --> 00:06:27,480 to link the songList to the albumList, 153 00:06:27,480 --> 00:06:30,810 so let's go ahead and do that. 154 00:06:30,810 --> 00:06:34,060 Then we'll do, this case albumList.link 155 00:06:35,800 --> 00:06:38,770 and that's going to be to songList in this case 156 00:06:38,770 --> 00:06:43,470 and then album, that's the column name, or the field. 157 00:06:43,470 --> 00:06:45,050 Alright, so let's run the programme. 158 00:06:45,050 --> 00:06:47,830 It should allow the album and songLists to be updated 159 00:06:47,830 --> 00:06:50,840 when items are selected in the list that they're linked to, 160 00:06:50,840 --> 00:06:54,090 so we'll actually run that and see. 161 00:06:54,090 --> 00:06:57,170 Go ahead and have a look at the code, 162 00:06:58,250 --> 00:07:00,420 and we can select, should be able to select an artist, 163 00:07:00,420 --> 00:07:02,970 we can see that's updating okay, 164 00:07:02,970 --> 00:07:05,520 and if I come over and click on an album 165 00:07:05,520 --> 00:07:07,630 we actually get a crash, 166 00:07:07,630 --> 00:07:09,320 so it's almost working. 167 00:07:09,320 --> 00:07:11,740 So selecting the artists you saw worked fine 168 00:07:11,740 --> 00:07:13,340 and the correct albums are displayed, 169 00:07:13,340 --> 00:07:15,410 but soon as I actually selected an album 170 00:07:15,410 --> 00:07:17,020 we actually had a crash. 171 00:07:17,020 --> 00:07:19,150 And if you come down here and look at the error, 172 00:07:19,150 --> 00:07:21,600 and I'll just close that down for now, 173 00:07:21,600 --> 00:07:22,830 and the error's saying here 174 00:07:22,830 --> 00:07:25,270 that there's no such column artists. 175 00:07:25,270 --> 00:07:26,810 Well the songs table doesn't actually have 176 00:07:26,810 --> 00:07:29,200 an artists column, so we shouldn't be referring 177 00:07:29,200 --> 00:07:31,500 to the artists column in the songs table, 178 00:07:31,500 --> 00:07:34,190 so obviously at this point something's not right. 179 00:07:34,190 --> 00:07:37,150 So if you click on this link to here in the error trace, 180 00:07:37,150 --> 00:07:41,190 that actually takes us to the line where the problem is. 181 00:07:41,190 --> 00:07:42,240 Well, that's actually the line 182 00:07:42,240 --> 00:07:43,980 that's actually executing the sql, 183 00:07:43,980 --> 00:07:46,150 but if you look above on line 56 184 00:07:46,150 --> 00:07:48,050 that's actually where the problem is. 185 00:07:48,050 --> 00:07:50,340 So I've still got the artists column hard coded 186 00:07:50,340 --> 00:07:53,660 as you can see here, into the sql where clause, 187 00:07:53,660 --> 00:07:56,060 and what we should be doing is using the link field, 188 00:07:56,060 --> 00:07:58,810 the one that was set when we call the link method, 189 00:07:58,810 --> 00:08:00,130 so let's go ahead and change that. 190 00:08:00,130 --> 00:08:04,050 So I'm going to delete the artist in the double quotes 191 00:08:04,050 --> 00:08:08,220 and we're going to replace that with self.link_field 192 00:08:09,390 --> 00:08:11,940 so we get the right column for the right table. 193 00:08:11,940 --> 00:08:13,980 But that raises another question, now, 194 00:08:13,980 --> 00:08:15,180 and that question is, what happens 195 00:08:15,180 --> 00:08:17,420 if we don't have a link field, 196 00:08:17,420 --> 00:08:20,180 because the listBox hasn't been linked to another one? 197 00:08:20,180 --> 00:08:22,020 Well in that cause, calling requery 198 00:08:22,020 --> 00:08:24,240 should populate the list with all the rows 199 00:08:24,240 --> 00:08:25,730 so we wanna execute the code 200 00:08:25,730 --> 00:08:27,650 in the else block in that scenario. 201 00:08:27,650 --> 00:08:31,200 So we can fix this by adding a test for the link_field 202 00:08:31,200 --> 00:08:33,299 as well as the link_value. 203 00:08:33,299 --> 00:08:34,480 So if we go ahead and do that, 204 00:08:34,480 --> 00:08:37,980 so I've got if link_value here on line 55, 205 00:08:38,880 --> 00:08:43,049 if we do or add the words "and" and self.link_field 206 00:08:45,970 --> 00:08:47,400 we're now only gonna execute that 207 00:08:47,400 --> 00:08:49,240 if there is a link that has been established 208 00:08:49,240 --> 00:08:51,640 between the two listBoxes. 209 00:08:51,640 --> 00:08:54,040 Otherwise the else code is gonna be executed, 210 00:08:54,040 --> 00:08:56,750 and reflectively going to get the entire contents 211 00:08:56,750 --> 00:08:58,790 of the table added to the listBox 212 00:08:58,790 --> 00:09:01,400 and that's actually what we want in this scenario. 213 00:09:01,400 --> 00:09:05,360 Alright, so we're going to also make a change down here 214 00:09:05,360 --> 00:09:07,750 after the call to self.clear, 215 00:09:07,750 --> 00:09:09,980 then we're actually through and adding the code there 216 00:09:09,980 --> 00:09:13,510 so you can see that adds the entries to the listBox. 217 00:09:13,510 --> 00:09:16,030 What we need to do also is down here 218 00:09:16,030 --> 00:09:18,950 put in some code if self.linked_box 219 00:09:22,210 --> 00:09:25,460 then we wanna do self.linked_box.clear. 220 00:09:28,830 --> 00:09:29,730 Now the reason we're doing that, 221 00:09:29,730 --> 00:09:32,900 that's to clear out the data in any linked data listBox 222 00:09:32,900 --> 00:09:35,420 so that way when we select a new artist 223 00:09:35,420 --> 00:09:38,620 the songs for the previous album aren't still displayed, 224 00:09:38,620 --> 00:09:39,720 and that's the reason, by the way, 225 00:09:39,720 --> 00:09:42,600 that we added a clear method in the first place 226 00:09:42,600 --> 00:09:45,430 rather than just deleting the list items earlier. 227 00:09:45,430 --> 00:09:47,350 So we need a method on the linked listBox 228 00:09:47,350 --> 00:09:49,300 to tell it to delete its contents. 229 00:09:49,300 --> 00:09:50,960 Alright, so let's actually try running this again, 230 00:09:50,960 --> 00:09:55,130 and hopefully things will actually work properly now. 231 00:09:58,980 --> 00:10:01,320 Alright, so if I select an artist, 232 00:10:01,320 --> 00:10:02,520 okay, so we've got an error there, 233 00:10:02,520 --> 00:10:04,040 let's just have a look. 234 00:10:04,040 --> 00:10:07,090 Can't convert DataListBox object to string implicitly, 235 00:10:07,090 --> 00:10:08,640 okay just click on that, 236 00:10:08,640 --> 00:10:09,840 and I've made a typo here, 237 00:10:09,840 --> 00:10:13,140 I've actually typed in self.linked_box, 238 00:10:13,140 --> 00:10:14,870 but it actually should be link_field, 239 00:10:14,870 --> 00:10:17,610 because the field is ultimately gonna be 240 00:10:17,610 --> 00:10:18,980 the column name for the database 241 00:10:18,980 --> 00:10:20,080 that we're trying to add, 242 00:10:20,080 --> 00:10:22,940 so that's just a typo, so I'll fix that. 243 00:10:22,940 --> 00:10:26,290 Link_field, that should fix that up, 244 00:10:26,290 --> 00:10:29,370 so let's just try running that again. 245 00:10:35,150 --> 00:10:37,990 Let's see how we go this time. 246 00:10:37,990 --> 00:10:40,590 Alright so, we'll try running it again, 247 00:10:40,590 --> 00:10:41,980 this time we haven't got an error there, that's good, 248 00:10:41,980 --> 00:10:43,510 so we've got artists showing, 249 00:10:43,510 --> 00:10:45,790 albums you saw was updating automatically, 250 00:10:45,790 --> 00:10:46,870 so each time we're clicking we're getting 251 00:10:46,870 --> 00:10:48,610 the list of albums, so that's good, 252 00:10:48,610 --> 00:10:50,400 and multiple albums are being shown. 253 00:10:50,400 --> 00:10:52,170 Now if we click on an album 254 00:10:52,170 --> 00:10:53,760 we're correctly getting the list of songs, 255 00:10:53,760 --> 00:10:56,090 and that's updating as well. 256 00:10:56,090 --> 00:10:58,460 So that's good, everything's now working great, 257 00:10:58,460 --> 00:11:00,230 and you can see that as I was selecting items 258 00:11:00,230 --> 00:11:01,860 in any one odd data listBox, 259 00:11:01,860 --> 00:11:03,770 the corresponding data is displayed 260 00:11:03,770 --> 00:11:05,880 in the linked data listBox, 261 00:11:05,880 --> 00:11:08,200 and I think at this point that's pretty impressive. 262 00:11:08,200 --> 00:11:11,290 So we've taken the basic tkinter listbox 263 00:11:11,290 --> 00:11:14,350 and now created our own scrollable version of it, 264 00:11:14,350 --> 00:11:16,870 and with that extended that further 265 00:11:16,870 --> 00:11:18,460 to produce a data listBox that can 266 00:11:18,460 --> 00:11:21,300 load its own data from a database table 267 00:11:21,300 --> 00:11:24,550 as well as triggering loading in another data listBox. 268 00:11:24,550 --> 00:11:27,340 So the code in the main programme becomes a lot cleaner 269 00:11:27,340 --> 00:11:30,270 and easier to instal as a result of this, 270 00:11:30,270 --> 00:11:31,750 but with that said we've still got a bit 271 00:11:31,750 --> 00:11:34,430 of tidying up to do there in the code 272 00:11:34,430 --> 00:11:35,880 before I end this video, 273 00:11:35,880 --> 00:11:38,770 and I'm just gonna close this down. 274 00:11:38,770 --> 00:11:40,400 Now to start with, we don't need 275 00:11:40,400 --> 00:11:43,280 this get_songs function anymore 276 00:11:43,280 --> 00:11:46,820 'cause that's now all handled by our data listBox class, 277 00:11:46,820 --> 00:11:48,840 and we also don't need to connect to the database 278 00:11:48,840 --> 00:11:50,750 right at the start of the programme. 279 00:11:50,750 --> 00:11:52,810 Now, we did that originally because our functions 280 00:11:52,810 --> 00:11:55,200 were using the global database connexion, 281 00:11:55,200 --> 00:11:56,760 but now that we're passing the connexion 282 00:11:56,760 --> 00:11:58,550 to our data listBox objects 283 00:11:58,550 --> 00:12:01,200 that code can come down to the main programme. 284 00:12:01,200 --> 00:12:02,860 We should also add a condition 285 00:12:02,860 --> 00:12:04,500 so that the main code isn't executed 286 00:12:04,500 --> 00:12:06,920 when the module's imported by another programme, 287 00:12:06,920 --> 00:12:08,840 and that'll then let other programmes 288 00:12:08,840 --> 00:12:11,690 use our scroll box and data listBox classes. 289 00:12:11,690 --> 00:12:12,750 Let's go ahead and do that, 290 00:12:12,750 --> 00:12:15,960 so I'm actually going to delete the get_songs function 291 00:12:15,960 --> 00:12:17,370 because that's existed in quite a few 292 00:12:17,370 --> 00:12:20,120 other versions of the video prior to this, 293 00:12:20,120 --> 00:12:23,690 or videos prior to this, so we don't need to preserve that, 294 00:12:23,690 --> 00:12:25,720 and clean up some of this. 295 00:12:25,720 --> 00:12:28,210 Let's also add that code there 296 00:12:28,210 --> 00:12:30,200 to make sure that the main code 297 00:12:30,200 --> 00:12:32,080 isn't executed when the module's imported. 298 00:12:32,080 --> 00:12:35,330 So if __name__ is equal to '__main__' : 299 00:12:43,530 --> 00:12:45,060 and from there we want to indent the code 300 00:12:45,060 --> 00:12:48,810 but we gotta start by moving this connexion, 301 00:12:49,740 --> 00:12:52,680 I'll comment that out and we'll delete this, 302 00:12:52,680 --> 00:12:55,110 clear up some spaces there, 303 00:12:55,110 --> 00:12:58,360 then I'm gonna come down and put that code in here, 304 00:12:58,360 --> 00:13:01,520 and then we're going to indent this other code, 305 00:13:01,520 --> 00:13:02,420 then go right down to the bottom 306 00:13:02,420 --> 00:13:05,080 and indent all of that, like so. 307 00:13:07,350 --> 00:13:09,100 Now we also were loading data 308 00:13:09,100 --> 00:13:11,790 into the albums and songLists when the programme starts, 309 00:13:11,790 --> 00:13:13,840 and if you recall we did that when testing earlier 310 00:13:13,840 --> 00:13:16,480 but we can now go ahead and delete those lines now. 311 00:13:16,480 --> 00:13:18,330 So in terms of that code you've got 312 00:13:18,330 --> 00:13:21,310 this requery here, firstly for albums, 313 00:13:21,310 --> 00:13:23,710 so let's, I'll just comment that out. 314 00:13:23,710 --> 00:13:26,000 You could just as easily delete that if you prefer. 315 00:13:26,000 --> 00:13:29,100 We've also got another one in the songs, 316 00:13:29,100 --> 00:13:31,040 the songlist.requery, which we no longer need 317 00:13:31,040 --> 00:13:32,580 to have that code there anymore. 318 00:13:32,580 --> 00:13:33,790 But of course we do wanna leave 319 00:13:33,790 --> 00:13:35,290 the original artists in there, 320 00:13:35,290 --> 00:13:37,100 so that all the artists are initially loaded, 321 00:13:37,100 --> 00:13:39,550 so that's good, that's now fixed. 322 00:13:39,550 --> 00:13:41,340 And down here for the main loop 323 00:13:41,340 --> 00:13:42,810 we can also get rid of the testList 324 00:13:42,810 --> 00:13:45,230 and the albumLV.set tuple, 325 00:13:45,230 --> 00:13:48,110 you don't actually want that to be populated either, 326 00:13:48,110 --> 00:13:49,680 so let's actually get rid of that as well, 327 00:13:49,680 --> 00:13:51,570 comment that out. 328 00:13:51,570 --> 00:13:54,630 Which really only leaves the code for the main loop 329 00:13:54,630 --> 00:13:56,970 in printing, the fact that we're closing 330 00:13:56,970 --> 00:13:59,830 the database connexion and then the connection.close, 331 00:13:59,830 --> 00:14:03,990 so let's just run this to make sure that it still works. 332 00:14:08,300 --> 00:14:10,740 So I've now only got the artists populated initially. 333 00:14:10,740 --> 00:14:13,740 We can click on a particular artist. 334 00:14:14,940 --> 00:14:17,210 By the way, we can click on songs as well, 335 00:14:17,210 --> 00:14:20,240 and because that's not associated with any other listBox 336 00:14:20,240 --> 00:14:21,240 we're not getting any errors, 337 00:14:21,240 --> 00:14:23,940 and that's working as well as we think it should be working, 338 00:14:23,940 --> 00:14:26,420 and we're still getting our other selects working correctly 339 00:14:26,420 --> 00:14:29,990 and the various data listBoxes being updated on the screen. 340 00:14:29,990 --> 00:14:33,440 So that's actually it, that's our data ListBox finished. 341 00:14:33,440 --> 00:14:35,120 I think you'd agree that the main program's now 342 00:14:35,120 --> 00:14:37,020 a lot tidier than what it was, 343 00:14:37,020 --> 00:14:39,180 and we haven't got any code copied and pasted, 344 00:14:39,180 --> 00:14:40,600 more to the point. 345 00:14:40,600 --> 00:14:44,350 We've also now got two completely reusable classes 346 00:14:44,350 --> 00:14:46,330 that we can import into other projects 347 00:14:46,330 --> 00:14:47,810 whenever we need a scrolling listBox 348 00:14:47,810 --> 00:14:51,620 or one that can display data from a database table. 349 00:14:51,620 --> 00:14:54,480 Now, there is a bug in the data listBox class, though. 350 00:14:54,480 --> 00:14:55,400 Let's see if you can figure out 351 00:14:55,400 --> 00:14:57,180 and try and spot what that is. 352 00:14:57,180 --> 00:14:59,630 In the next video I'm gonna show you what the bug is 353 00:14:59,630 --> 00:15:02,550 and then set you a challenge to fix that bug, 354 00:15:02,550 --> 00:15:04,880 so I will see you in the next video.