1 00:00:01,530 --> 00:00:07,290 So in our application, we've been using the built in HTML template package, which is part of the standard 2 00:00:07,290 --> 00:00:11,070 library and go, and I think it's important to know how that library works. 3 00:00:11,820 --> 00:00:17,640 But those of you that are coming to Web development and go from other languages might find that the 4 00:00:17,640 --> 00:00:23,220 syntax for templates in goaland is a little awkward and it is, but it gets the job done and you get 5 00:00:23,220 --> 00:00:24,330 used to it very quickly. 6 00:00:24,330 --> 00:00:26,430 And I think it's very important that you know what it is. 7 00:00:27,240 --> 00:00:33,150 Having said that, there are other template systems out there and there are many to choose from. 8 00:00:33,150 --> 00:00:37,340 You can actually just Google Goaland template engines and you'll get a list of a whole bunch of them. 9 00:00:37,740 --> 00:00:43,140 I want to draw your attention to one, and I want to show you a very, very simple application that 10 00:00:43,140 --> 00:00:44,700 uses this templating system. 11 00:00:45,120 --> 00:00:51,570 So the templating system is found here, GitHub, dot com, cloudy kett with a capital C and a capital 12 00:00:51,570 --> 00:00:53,280 K jet. 13 00:00:53,760 --> 00:00:55,020 And it's been around for a while. 14 00:00:55,020 --> 00:00:56,220 It's up to version six. 15 00:00:56,220 --> 00:01:01,780 As I record this and I use it all the time, I use sometimes I use go templates, sometimes I use cloud 16 00:01:01,780 --> 00:01:03,480 tickets, sometimes I use something else. 17 00:01:03,900 --> 00:01:10,290 But Jet is something that many of you who are used to using, say, blade templates and Laravel might 18 00:01:10,290 --> 00:01:11,720 be find this a little more useful. 19 00:01:11,820 --> 00:01:13,560 It's very, very simple to implement. 20 00:01:13,570 --> 00:01:16,820 So you can read all the documentation here and I'll show you how it works. 21 00:01:17,520 --> 00:01:20,550 So they actually have a syntax reference, a nice wiki. 22 00:01:20,550 --> 00:01:24,600 Some things are out of date, but it's easy to figure it out and I'll show you how it works here anyway. 23 00:01:25,110 --> 00:01:27,740 So I'm going to go back to my application and just take you through the code. 24 00:01:27,990 --> 00:01:29,430 So very simple app. 25 00:01:29,430 --> 00:01:36,270 I'm in my main package, which is in command Web main, and I just define some routes. 26 00:01:36,270 --> 00:01:39,570 And for this one, I used the I think I use Pat. 27 00:01:39,570 --> 00:01:40,890 Let's find the routes and find out. 28 00:01:41,010 --> 00:01:45,000 Yes, I use the pat the pat router, which I went through in this course already. 29 00:01:45,540 --> 00:01:50,640 And I just define two routes slash, which is the home page and send, which is just an empty page. 30 00:01:50,640 --> 00:01:51,780 I needed to put something there. 31 00:01:51,780 --> 00:01:56,070 So I put send so back to our main goal. 32 00:01:56,100 --> 00:02:01,380 Once we do this we actually listen and serve and we listen on Port AT&T, as we've been doing in our 33 00:02:01,380 --> 00:02:01,880 course. 34 00:02:02,280 --> 00:02:06,150 So let's go look and see what some of these handlers, how they work. 35 00:02:06,270 --> 00:02:09,000 OK, so I'll go to the homepage and the home page. 36 00:02:09,600 --> 00:02:11,160 This is the handler for the home page. 37 00:02:11,160 --> 00:02:16,620 And just as it does in our course, it takes a response writer and a pointer to a request. 38 00:02:16,860 --> 00:02:20,730 And then I just built up some data, just dummy data to send to a template. 39 00:02:20,730 --> 00:02:22,950 Let me space this out a bit so you can see a little better. 40 00:02:24,180 --> 00:02:29,070 So I start by defining a jet versus map variable. 41 00:02:29,190 --> 00:02:33,890 OK, so I just make that and it holds anything I want. 42 00:02:34,230 --> 00:02:38,790 So once I've created this variable called data, I call in the builtin method. 43 00:02:38,790 --> 00:02:41,910 I call the builtin method set and I give it a name. 44 00:02:41,940 --> 00:02:46,140 This is what I'm going to refer to it in using my jet template. 45 00:02:46,710 --> 00:02:49,650 And I just store some value in there and I can put whatever I want in there. 46 00:02:49,650 --> 00:02:56,310 So initially I just said user ID is equal to one, then I set another one first for first name is equal 47 00:02:56,310 --> 00:03:01,170 to a string, so I put it into one, I put a string in, then I define a slice of strings, which are 48 00:03:01,170 --> 00:03:07,650 the days of the week, and I set a variable in my data called DSW four days of week and passed in that 49 00:03:07,650 --> 00:03:08,550 slice of strings. 50 00:03:09,360 --> 00:03:13,410 Then I called Render Page and I'm passing that three things. 51 00:03:13,560 --> 00:03:16,380 I'm passing it the response rate, which I need to write to. 52 00:03:16,680 --> 00:03:20,700 That's what's going to be how we render information to the end user and their web browser. 53 00:03:21,210 --> 00:03:24,240 The name of the template I want to load and then the data. 54 00:03:24,270 --> 00:03:28,050 Now, this render page is not part of the template package. 55 00:03:28,050 --> 00:03:31,470 Just to be clear, I'm just calling my own function, which is right down here. 56 00:03:32,160 --> 00:03:41,400 And all I do is I have those three arguments and I create I have a variable called views and I call 57 00:03:41,400 --> 00:03:42,060 get template. 58 00:03:42,060 --> 00:03:45,600 Now, view is way up here and that's a jetset. 59 00:03:45,600 --> 00:03:51,840 And this is what you have to have to start with to make sure that you can actually use the jet template 60 00:03:51,840 --> 00:03:52,200 engine. 61 00:03:52,200 --> 00:03:53,310 And it's really, really simple. 62 00:03:54,060 --> 00:03:57,840 So I say, first of all, there's an OS file system loader. 63 00:03:57,870 --> 00:04:01,530 Look at the root level of the application in a folder called HTML. 64 00:04:01,560 --> 00:04:08,760 And over here I have an HTML folder that has two files home and sent the second one I put in development 65 00:04:08,760 --> 00:04:13,800 mode because I want to be able to load changes to my template without starting or stopping and restarting 66 00:04:13,800 --> 00:04:17,430 the application, kind of like the cache variable we used in our system. 67 00:04:18,630 --> 00:04:21,510 So I have this variable views down here. 68 00:04:21,660 --> 00:04:27,900 I say view error is equal to or assign the value of views, get the template wherever it is. 69 00:04:28,080 --> 00:04:30,030 Now, I passed homecourt jet here. 70 00:04:30,030 --> 00:04:31,440 So it goes to the file system. 71 00:04:31,740 --> 00:04:37,230 It looks in the directory I specified, which I called HTML and it looks for a file called Homeport 72 00:04:37,290 --> 00:04:39,120 Jet, which is the argument I passed. 73 00:04:40,230 --> 00:04:42,120 So it can't get that. 74 00:04:42,300 --> 00:04:44,670 It just returns an error and logs the error. 75 00:04:44,910 --> 00:04:51,840 Otherwise I execute that view, that homecourt jet and I pass it my response writer, because it gives 76 00:04:51,840 --> 00:04:58,860 it something to write to the data, which is that jet set variable that I defined a little while ago 77 00:04:58,860 --> 00:04:59,910 and put a few values. 78 00:05:00,690 --> 00:05:02,520 And the third one is actually context. 79 00:05:02,550 --> 00:05:03,840 I'm not going to bother going through that. 80 00:05:03,840 --> 00:05:05,090 You can read it yourself. 81 00:05:05,100 --> 00:05:11,340 It's another place to store information and it uses the context to store that that executes that template 82 00:05:11,340 --> 00:05:13,350 if it can't execute it, if it turns an error. 83 00:05:13,410 --> 00:05:21,630 So let's start this application, go run command web main or start go try that again. 84 00:05:21,780 --> 00:05:26,360 Stargirl starts the application, listens on Port AT&T. 85 00:05:26,370 --> 00:05:35,130 I go back to my Web browser, I go to a tab and I go to localhost AT&T and I'm not going to put anything 86 00:05:35,130 --> 00:05:35,340 in there. 87 00:05:35,340 --> 00:05:37,680 I want to display the homepage and there it is. 88 00:05:37,680 --> 00:05:39,750 It displays at all very, very simple. 89 00:05:39,990 --> 00:05:43,980 Let's go look at the template and see how that how that is different from the built in go templates. 90 00:05:44,790 --> 00:05:45,690 It's actually pretty simple. 91 00:05:45,700 --> 00:05:49,570 So let me go to the homepage and hide this and have a look. 92 00:05:49,620 --> 00:05:51,990 So this is just a simple HTML page. 93 00:05:52,260 --> 00:05:58,230 I just load bootstraps success and bootstraps JavaScript, which I'm not even using, but I load it 94 00:05:58,560 --> 00:06:01,890 and then I just say this is the homepage and then user ID. 95 00:06:02,160 --> 00:06:05,240 I just refer to user ID with no dot. 96 00:06:05,280 --> 00:06:06,570 That's one difference right away. 97 00:06:07,320 --> 00:06:14,940 And the first name is first with no dot and ranging over things range key value is a the value of and 98 00:06:14,940 --> 00:06:15,980 that's pretty straightforward. 99 00:06:16,140 --> 00:06:20,940 Now the syntax is actually a little simpler than it is in the goal line templates and you have some 100 00:06:20,940 --> 00:06:22,140 built in functions as well. 101 00:06:22,140 --> 00:06:26,550 So let's go back and look at those cloudy kit will go to the wiki. 102 00:06:27,600 --> 00:06:29,360 Some things are out of date, but not too many. 103 00:06:29,460 --> 00:06:32,520 Someday I'm going to go rewrite his documentation and give it to him. 104 00:06:33,030 --> 00:06:38,670 So built in functions, for example, you get some nice simple built in functions to change things to 105 00:06:38,670 --> 00:06:44,880 lowercase, to uppercase, to trim space, check, to see if a variable is actually there or not, which 106 00:06:44,880 --> 00:06:47,610 a lot of people miss and go like templates, including me. 107 00:06:48,420 --> 00:06:50,760 And you get all of these other ones as well. 108 00:06:51,030 --> 00:06:54,000 And the documentation is really, really easy to work with. 109 00:06:54,000 --> 00:07:01,830 So, for example, let's see if we can find decisions, if then else here we are if expression and see 110 00:07:01,830 --> 00:07:03,030 how easy this is. 111 00:07:03,030 --> 00:07:10,350 And it's simpler than using the ECU or any or all of those little comparison operators that you have 112 00:07:10,350 --> 00:07:11,490 in the go line templates. 113 00:07:11,520 --> 00:07:16,890 Now, it sounds as though I'm suggesting you use jet templates instead of the built in go templates, 114 00:07:16,890 --> 00:07:18,780 and nothing could be further from the truth. 115 00:07:18,780 --> 00:07:25,590 I think it's really important that people coming to go for the first time become used to the built in 116 00:07:25,590 --> 00:07:28,740 templating syntax because you're going to run into it in other projects. 117 00:07:29,880 --> 00:07:34,050 But once you've mastered that or you're really comfortable with it, if you want to use something like 118 00:07:34,050 --> 00:07:36,090 Jet, there's nothing to stop you from doing that. 119 00:07:36,090 --> 00:07:37,590 And a lot of people find it easier. 120 00:07:38,070 --> 00:07:42,600 Also, templated inheritance is built in all those things that you really expect to find from a good 121 00:07:42,600 --> 00:07:43,500 templating package. 122 00:07:44,100 --> 00:07:45,210 All right, one other thing. 123 00:07:45,210 --> 00:07:46,350 I want to draw your attention. 124 00:07:46,440 --> 00:07:47,970 So this is my homepage. 125 00:07:48,600 --> 00:07:51,840 Here's one thing, one compelling reason why a lot of people come here. 126 00:07:51,840 --> 00:07:57,780 Let me define or refer to a variable ABC that I know doesn't exist, and I'll save that. 127 00:07:58,410 --> 00:07:59,970 And I'll go back to my. 128 00:08:01,250 --> 00:08:03,810 Web browser right here, find my home page. 129 00:08:03,860 --> 00:08:10,820 Let me reload this, and now it gives me a meaningful error message which is conspicuous by its absence 130 00:08:10,820 --> 00:08:13,060 in the built in go templating system. 131 00:08:13,700 --> 00:08:17,390 And this, if nothing else, is extremely helpful. 132 00:08:17,930 --> 00:08:18,950 So there you go. 133 00:08:18,960 --> 00:08:20,960 I just wanted to draw your attention to this. 134 00:08:20,960 --> 00:08:25,520 And if you really like jump chat templates and want to use those instead of the ones that I'm using 135 00:08:25,520 --> 00:08:28,630 for the remainder of this course, feel free to do so. 136 00:08:28,640 --> 00:08:34,970 But I would strongly encourage you to leave your experimentation with go templates to a separate project 137 00:08:35,270 --> 00:08:40,130 and follow along with the way that I'm doing it in this course or finish the course and then rewrite 138 00:08:40,130 --> 00:08:44,440 the pages in Jet, which is not a terribly onerous task.