1 00:00:01,170 --> 00:00:03,210 ‫And now, to finish this part, 2 00:00:03,210 --> 00:00:06,363 ‫let's incorporate a geolocation feature. 3 00:00:07,590 --> 00:00:11,310 ‫And to do that, you will actually bring back the custom hook 4 00:00:11,310 --> 00:00:15,180 ‫that we wrote earlier in one of the challenges. 5 00:00:15,180 --> 00:00:17,430 ‫Now, if you didn't complete that challenge, 6 00:00:17,430 --> 00:00:20,310 ‫then you can just grab this custom hook here 7 00:00:20,310 --> 00:00:24,270 ‫from this URL that I will provide in this lecture. 8 00:00:24,270 --> 00:00:27,630 ‫And so this is now really the power of custom hooks. 9 00:00:27,630 --> 00:00:30,870 ‫So we just write them once, and then we can drop them 10 00:00:30,870 --> 00:00:33,630 ‫into any project that we want, 11 00:00:33,630 --> 00:00:36,930 ‫at least if we made them reusable enough. 12 00:00:36,930 --> 00:00:39,120 ‫So let's just copy... 13 00:00:39,120 --> 00:00:41,700 ‫Well, actually we're missing this part, 14 00:00:41,700 --> 00:00:45,870 ‫so let's copy all of this. 15 00:00:45,870 --> 00:00:50,870 ‫And then let's first create a new folder here for our hooks. 16 00:00:52,410 --> 00:00:56,340 ‫So then we get a new nice icon there. 17 00:00:56,340 --> 00:00:59,673 ‫And then let's say useGeolocation.js. 18 00:01:04,740 --> 00:01:07,560 ‫So this one doesn't have to be a JSX file 19 00:01:07,560 --> 00:01:10,710 ‫because we are not exporting any JSX. 20 00:01:10,710 --> 00:01:13,113 ‫So it's just a JavaScript function. 21 00:01:14,340 --> 00:01:18,300 ‫Now, here we are missing the useState hook, 22 00:01:18,300 --> 00:01:20,970 ‫so let's include it like this, 23 00:01:20,970 --> 00:01:25,970 ‫and then let's actually export this function from here. 24 00:01:27,540 --> 00:01:30,540 ‫And here I'm not doing a default export, 25 00:01:30,540 --> 00:01:32,820 ‫but really a named export. 26 00:01:32,820 --> 00:01:35,460 ‫So that's how I like to do it with hooks, 27 00:01:35,460 --> 00:01:38,820 ‫because sometimes we can have multiple custom hooks 28 00:01:38,820 --> 00:01:40,050 ‫in the same file. 29 00:01:40,050 --> 00:01:42,720 ‫And so then it's easier to have this convention, 30 00:01:42,720 --> 00:01:46,560 ‫where we always export them with named exports. 31 00:01:46,560 --> 00:01:48,870 ‫Now, there's just one thing that I want to change 32 00:01:48,870 --> 00:01:51,570 ‫in this custom hook, which is to have it 33 00:01:51,570 --> 00:01:53,973 ‫allow a default position. 34 00:01:56,190 --> 00:02:00,060 ‫So I want this custom hook to receive a default position, 35 00:02:00,060 --> 00:02:04,740 ‫but if not, then let's set the position to null. 36 00:02:04,740 --> 00:02:07,950 ‫So to null instead of an empty object 37 00:02:07,950 --> 00:02:09,510 ‫that we have right now. 38 00:02:09,510 --> 00:02:11,340 ‫So I think that the empty object 39 00:02:11,340 --> 00:02:12,930 ‫doesn't make a lot of sense, 40 00:02:12,930 --> 00:02:14,970 ‫and instead, this should be null. 41 00:02:14,970 --> 00:02:19,110 ‫And so here, let's now use that default position 42 00:02:19,110 --> 00:02:23,343 ‫which will default to null if it's not set. 43 00:02:24,390 --> 00:02:28,890 ‫Okay, and so with this, we can then use 44 00:02:28,890 --> 00:02:31,410 ‫the get position function on any button 45 00:02:31,410 --> 00:02:35,250 ‫to retrieve the current position of our user. 46 00:02:35,250 --> 00:02:39,180 ‫And so let's use that here now. 47 00:02:39,180 --> 00:02:43,410 ‫And like to always have all my hooks at the very top 48 00:02:43,410 --> 00:02:45,633 ‫to keep the code a bit more organized. 49 00:02:46,770 --> 00:02:48,153 ‫So let's do that here. 50 00:02:50,670 --> 00:02:52,443 ‫And for now, just leaving it empty. 51 00:02:53,550 --> 00:02:55,173 ‫So useGeolocation. 52 00:02:58,650 --> 00:03:02,343 ‫And then we have have to manually import that here. 53 00:03:03,900 --> 00:03:06,607 ‫Import useGeolocation from... 54 00:03:12,450 --> 00:03:15,900 ‫We need to move up, then into the hooks folder, 55 00:03:15,900 --> 00:03:17,573 ‫and useGeolocation. 56 00:03:19,341 --> 00:03:22,860 ‫Now let's just check again what this actually exports. 57 00:03:22,860 --> 00:03:27,860 ‫So it exports isLoading, position, error, and getPosition. 58 00:03:28,050 --> 00:03:31,383 ‫Now, let's not use the error, but only these other ones. 59 00:03:33,570 --> 00:03:38,570 ‫So isLoading, but since we are already using a variable 60 00:03:39,480 --> 00:03:42,630 ‫with this name, let's actually rename it. 61 00:03:42,630 --> 00:03:44,613 ‫So isLoadingPosition. 62 00:03:46,830 --> 00:03:49,053 ‫So just to avoid any confusion. 63 00:03:52,140 --> 00:03:55,170 ‫Then we have to position, and let's again rename it 64 00:03:55,170 --> 00:03:59,667 ‫to geolocationPosition so that we are really sure 65 00:04:01,740 --> 00:04:04,680 ‫what each of the variable names mean. 66 00:04:04,680 --> 00:04:09,513 ‫And then let's also get the getPosition function. 67 00:04:10,350 --> 00:04:14,482 ‫Okay, and now we need to trigger this 68 00:04:14,482 --> 00:04:16,830 ‫with the button right here. 69 00:04:16,830 --> 00:04:20,700 ‫So let's place that button also right here in this div, 70 00:04:20,700 --> 00:04:22,743 ‫so beside this map container. 71 00:04:24,030 --> 00:04:27,330 ‫So for this, we will bring back our button component 72 00:04:27,330 --> 00:04:28,653 ‫that we built earlier. 73 00:04:30,570 --> 00:04:34,053 ‫And then here, this one is of the type of position. 74 00:04:35,340 --> 00:04:40,280 ‫So I know that because here in the CSS module, 75 00:04:41,250 --> 00:04:44,100 ‫that's one of the types of classes that we have. 76 00:04:44,100 --> 00:04:46,650 ‫So we have the primary button, the back button, 77 00:04:46,650 --> 00:04:49,950 ‫and the position button, and that's it. 78 00:04:49,950 --> 00:04:51,243 ‫So only those three. 79 00:04:52,740 --> 00:04:54,990 ‫And here we also need the onClick handler, 80 00:04:54,990 --> 00:04:57,960 ‫which is simply getPosition, like this. 81 00:05:02,400 --> 00:05:04,890 ‫And then here, let's do some conditional rendering 82 00:05:04,890 --> 00:05:09,890 ‫and ask isLoadingPosition, then here display 83 00:05:11,130 --> 00:05:16,130 ‫loading and otherwise use your position. 84 00:05:19,110 --> 00:05:21,060 ‫Okay, nice. 85 00:05:21,060 --> 00:05:24,243 ‫So we should already see that button here in our UI. 86 00:05:25,854 --> 00:05:26,687 ‫And there it is. 87 00:05:27,690 --> 00:05:30,390 ‫So let's just reload to make sure. 88 00:05:30,390 --> 00:05:31,773 ‫And now let's see. 89 00:05:32,790 --> 00:05:36,750 ‫So we click here and then we get the question 90 00:05:36,750 --> 00:05:39,510 ‫if we want to allow the geolocation. 91 00:05:39,510 --> 00:05:43,740 ‫So let's say so, and then at some point it will finish. 92 00:05:43,740 --> 00:05:46,650 ‫It will however, not do anything with the map yet, 93 00:05:46,650 --> 00:05:48,930 ‫because we haven't set that up. 94 00:05:48,930 --> 00:05:53,930 ‫But if we come here to our map component, 95 00:05:55,050 --> 00:05:59,450 ‫somewhere down here in this huge tree, then... 96 00:06:03,450 --> 00:06:06,213 ‫Now it went back to app, so that's not helpful. 97 00:06:08,040 --> 00:06:09,153 ‫Right here. 98 00:06:10,920 --> 00:06:12,660 ‫Yeah, we have our geolocation, 99 00:06:12,660 --> 00:06:15,600 ‫and then there we have our position. 100 00:06:15,600 --> 00:06:18,360 ‫And so what we want to do then with this position 101 00:06:18,360 --> 00:06:20,913 ‫is of course to move the map there. 102 00:06:22,380 --> 00:06:25,533 ‫All right, and so let's implement that. 103 00:06:26,490 --> 00:06:29,730 ‫So basically we need to do the same thing as before, 104 00:06:29,730 --> 00:06:33,510 ‫which is to synchronize this map position now 105 00:06:33,510 --> 00:06:35,700 ‫with the geolocation position. 106 00:06:35,700 --> 00:06:38,613 ‫So we will need another effect to do that. 107 00:06:39,510 --> 00:06:42,480 ‫Now, if we were not using the custom hook 108 00:06:42,480 --> 00:06:44,850 ‫for the geolocation, then we could of course 109 00:06:44,850 --> 00:06:49,710 ‫directly store the received position into map position. 110 00:06:49,710 --> 00:06:53,580 ‫So right here we would then... 111 00:06:53,580 --> 00:06:56,850 ‫Yeah, set map position right here. 112 00:06:56,850 --> 00:06:59,580 ‫However, since we are using this custom hook, 113 00:06:59,580 --> 00:07:02,040 ‫we cannot easily do that. 114 00:07:02,040 --> 00:07:05,250 ‫So we could of course pass in a setter function as well, 115 00:07:05,250 --> 00:07:07,680 ‫but that's not the point here. 116 00:07:07,680 --> 00:07:09,900 ‫So instead, this geolocation hook 117 00:07:09,900 --> 00:07:12,663 ‫should actually have its own position state. 118 00:07:14,010 --> 00:07:17,490 ‫We just happen to now want to synchronize 119 00:07:17,490 --> 00:07:19,950 ‫that state here with our map position 120 00:07:19,950 --> 00:07:22,893 ‫so that we can then display exactly that. 121 00:07:25,380 --> 00:07:28,383 ‫So let's do that here. 122 00:07:31,128 --> 00:07:32,880 ‫And so I was telling you about all that 123 00:07:32,880 --> 00:07:36,090 ‫because in React there's right now a push 124 00:07:36,090 --> 00:07:39,120 ‫to write as little effects as possible. 125 00:07:39,120 --> 00:07:41,970 ‫And so if we did what I mentioned earlier, 126 00:07:41,970 --> 00:07:45,030 ‫then we could just avoid this one. 127 00:07:45,030 --> 00:07:46,860 ‫So then we wouldn't need this effect. 128 00:07:46,860 --> 00:07:48,690 ‫But it's also not a big deal. 129 00:07:48,690 --> 00:07:51,480 ‫So all we're going to do is to just synchronize 130 00:07:51,480 --> 00:07:54,483 ‫two variables here, very similar to what we have here. 131 00:07:55,920 --> 00:07:58,560 ‫So here we will run this effect each time 132 00:07:58,560 --> 00:08:01,320 ‫that the geolocation position changes, 133 00:08:01,320 --> 00:08:03,540 ‫and then what we want to do here 134 00:08:03,540 --> 00:08:08,160 ‫is to check if the position actually exists. 135 00:08:08,160 --> 00:08:12,483 ‫So only if it exists, then we want to set the map position. 136 00:08:14,058 --> 00:08:15,990 ‫And then let's create an array here. 137 00:08:15,990 --> 00:08:20,990 ‫So geolocationPosition.lng, and geolocationposition., 138 00:08:22,800 --> 00:08:27,093 ‫actually here it's the LNG and here the latitude. 139 00:08:29,190 --> 00:08:31,260 ‫Okay, so at the beginning, 140 00:08:31,260 --> 00:08:35,610 ‫the geolocation position will by default still be null, 141 00:08:35,610 --> 00:08:38,250 ‫and so then this code here doesn't run. 142 00:08:38,250 --> 00:08:40,020 ‫But then, as we click this button, 143 00:08:40,020 --> 00:08:42,960 ‫the geolocation will get retrieved, 144 00:08:42,960 --> 00:08:46,470 ‫and then of course this state here will update. 145 00:08:46,470 --> 00:08:48,360 ‫And so then this effect will run, 146 00:08:48,360 --> 00:08:51,780 ‫which will then in turn set the map position, 147 00:08:51,780 --> 00:08:55,230 ‫which will re-render the whole component once more, 148 00:08:55,230 --> 00:08:59,790 ‫and then finally the map can move to that new position. 149 00:08:59,790 --> 00:09:03,120 ‫So basically this effect here introduces another render, 150 00:09:03,120 --> 00:09:05,610 ‫which is one of the reasons why we should avoid 151 00:09:05,610 --> 00:09:07,440 ‫having too many effects. 152 00:09:07,440 --> 00:09:10,383 ‫But we will learn more about that in the next section. 153 00:09:12,030 --> 00:09:15,570 ‫But anyway, I think with this we are done. 154 00:09:15,570 --> 00:09:18,270 ‫So let's check, and it should move 155 00:09:18,270 --> 00:09:20,313 ‫to somewhere close to Lisbon. 156 00:09:21,840 --> 00:09:24,810 ‫So yeah, there it is. 157 00:09:24,810 --> 00:09:27,330 ‫So this is not because there's a city there, 158 00:09:27,330 --> 00:09:30,810 ‫but really because that's where my GPS location 159 00:09:30,810 --> 00:09:32,130 ‫is pointed to. 160 00:09:32,130 --> 00:09:35,370 ‫But we can actually change that somewhere. 161 00:09:35,370 --> 00:09:38,130 ‫I haven't done that in a long time. 162 00:09:38,130 --> 00:09:43,130 ‫So maybe it's right here somewhere. 163 00:09:45,810 --> 00:09:48,060 ‫Yeah, I think it's in sensors. 164 00:09:48,060 --> 00:09:50,160 ‫Yeah, here we can set the location, 165 00:09:50,160 --> 00:09:52,023 ‫for example, to San Francisco. 166 00:09:53,100 --> 00:09:58,100 ‫And so if I do this again, then let's see what happens. 167 00:10:01,740 --> 00:10:04,293 ‫Yeah, we actually moved to San Francisco. 168 00:10:05,670 --> 00:10:09,930 ‫So that's where this is in the US west coast. 169 00:10:09,930 --> 00:10:14,930 ‫And so this did work, but now of course, let's go back. 170 00:10:14,970 --> 00:10:18,540 ‫And actually this button should really disappear 171 00:10:18,540 --> 00:10:21,513 ‫once the geolocation position has been received. 172 00:10:22,890 --> 00:10:26,460 ‫So the user will not suddenly move somewhere else, 173 00:10:26,460 --> 00:10:28,860 ‫and so it doesn't make a lot of sense 174 00:10:28,860 --> 00:10:32,790 ‫that this button stays here after the position 175 00:10:32,790 --> 00:10:35,040 ‫has already been received. 176 00:10:35,040 --> 00:10:40,040 ‫So yeah, let's load this button here conditionally. 177 00:10:41,670 --> 00:10:46,653 ‫So only if there is no geolocation position yet. 178 00:10:47,880 --> 00:10:50,250 ‫So in that case, display the button. 179 00:10:50,250 --> 00:10:52,293 ‫And so now it is gone. 180 00:10:53,370 --> 00:10:56,670 ‫Okay, and with this, our map here 181 00:10:56,670 --> 00:10:58,830 ‫is actually feature complete. 182 00:10:58,830 --> 00:11:03,830 ‫So it can move between cities like this, 183 00:11:04,230 --> 00:11:08,430 ‫and we can use our own position to also move the map 184 00:11:08,430 --> 00:11:11,580 ‫to that geo-located position. 185 00:11:11,580 --> 00:11:14,670 ‫And finally, as we click somewhere on the map, 186 00:11:14,670 --> 00:11:18,150 ‫that will then move there as well, open the form, 187 00:11:18,150 --> 00:11:22,590 ‫and place the current clicked position in the URL. 188 00:11:22,590 --> 00:11:25,110 ‫Great, and in the next lecture, 189 00:11:25,110 --> 00:11:28,770 ‫it's actually time to start working on this form. 190 00:11:28,770 --> 00:11:30,813 ‫So let's move there right away.