1 00:00:01,570 --> 00:00:08,020 So we have a driver package set up, and now it's time to use that driver package to connect our application 2 00:00:08,020 --> 00:00:11,550 to the database, and we're going to do that using the repository pattern. 3 00:00:12,100 --> 00:00:14,640 So we already have one repository, if you recall. 4 00:00:14,650 --> 00:00:18,700 And if we look at our main go file, we can see where that is. 5 00:00:19,660 --> 00:00:25,180 And that's way down here where we create a new repository and that calls Handler's new repo. 6 00:00:25,900 --> 00:00:32,620 And what we're going to do is add something to this repository, which is itself a repository, because 7 00:00:32,620 --> 00:00:39,430 our my goal here is to set up my application in such a way that right now I'm going to use postgrads. 8 00:00:39,460 --> 00:00:46,630 But if down the road I want to use, say, my as well or Maria DB or Oracle or some other database, 9 00:00:47,050 --> 00:00:48,190 I can do so. 10 00:00:48,460 --> 00:00:54,160 And when I make that change, I change as little of the application as possible. 11 00:00:54,190 --> 00:00:58,240 And the repository pattern is ideal for that particular situation. 12 00:00:58,930 --> 00:01:04,300 So what I'm going to do is I'm going to create a new package and I'm going to do it on my internal I'm 13 00:01:04,300 --> 00:01:05,680 going to create a new package. 14 00:01:06,280 --> 00:01:08,920 So I'll just create a new directory, which will be a package. 15 00:01:09,340 --> 00:01:11,200 And I'm going to call that repository. 16 00:01:13,850 --> 00:01:20,420 And inside of that, I'm going to create another package, so inside of the repository directory, I'll 17 00:01:20,720 --> 00:01:27,620 create another directory which I'm going to call DB Repo, and at the root level of repository, not 18 00:01:27,620 --> 00:01:31,220 inside the DP Rebo DB repo, but inside the repository folder. 19 00:01:31,220 --> 00:01:36,680 I'll create a gopher and I will call that repository Dongo. 20 00:01:37,790 --> 00:01:42,530 And I will add that to get and that file right now is very, very simple. 21 00:01:42,620 --> 00:01:50,060 I'm just going to create a type in here, an interface type, and I'll call it database repo, which 22 00:01:50,060 --> 00:01:53,930 is an interface, and right now it will be empty, will add something to that in a little while. 23 00:01:55,100 --> 00:01:59,210 And inside of the DB repo folder, I'll create a new file. 24 00:02:02,800 --> 00:02:08,760 And I will call that, not surprisingly, debri pogo, and I will add that to get as well. 25 00:02:10,150 --> 00:02:15,760 Now inside of here, I'm going to create a type and that type will be the repository itself and the 26 00:02:15,760 --> 00:02:20,200 type will be called Postgres Divi Repo. 27 00:02:20,950 --> 00:02:23,770 And it's a struct and it will hold two things. 28 00:02:23,800 --> 00:02:29,310 It will hold up an app, which will be a pointer to our config app config. 29 00:02:30,400 --> 00:02:35,800 So it's going to hold that and it's also going to hold a database connection pool, which, as you know, 30 00:02:35,800 --> 00:02:38,500 is a pointer to four postgrads of sequel. 31 00:02:38,500 --> 00:02:42,440 DeeVee So that's a type which I'm currently not using. 32 00:02:42,850 --> 00:02:44,230 Now I'm going to create a new function. 33 00:02:44,230 --> 00:02:50,560 And just as we did with our other repository, this is created using a function which I'll call new 34 00:02:50,620 --> 00:02:53,350 postgrads repoll. 35 00:02:56,170 --> 00:03:01,270 And it will take a parameter, actually a couple of parameters, one I'll call Con because it's a connection 36 00:03:01,270 --> 00:03:08,700 pool and it's a pointer to sequel DB and the other one is a and it's just a pointer to our config config 37 00:03:09,340 --> 00:03:14,680 and it's going to return a repository database repo. 38 00:03:16,210 --> 00:03:17,380 But our spell repository. 39 00:03:17,380 --> 00:03:17,580 Right. 40 00:03:21,220 --> 00:03:29,020 And just as we did with our other repository, we'll just return a reference to Postgrads Divi Rebo 41 00:03:29,650 --> 00:03:35,750 and of course, that has to take two arguments in order to be populated at which we have as a parameter 42 00:03:35,750 --> 00:03:40,580 we're passing here A and our DB, which will be our connection pool. 43 00:03:41,530 --> 00:03:41,970 All right. 44 00:03:42,490 --> 00:03:50,200 So now I have a means of passing this function, our connection pool and our app config and returning 45 00:03:50,200 --> 00:03:51,060 a repository. 46 00:03:51,100 --> 00:03:57,130 And because I'm now initializing this using new Postgres repo, it will be a connection pool that has 47 00:03:57,580 --> 00:03:58,690 Postgres connection pool. 48 00:03:59,680 --> 00:04:06,100 If I wanted to have another database, I would simply create a new type say type MySQL DB repo, which 49 00:04:06,130 --> 00:04:11,230 would hold whatever is required for that are up configuring a connection pool for for my school. 50 00:04:11,620 --> 00:04:17,650 And I'd create a new function called func new MySQL Repo and create that. 51 00:04:17,680 --> 00:04:21,760 So now I have a means of swapping out my database very, very quickly. 52 00:04:22,300 --> 00:04:22,710 All right. 53 00:04:22,720 --> 00:04:24,460 So this is created now. 54 00:04:24,460 --> 00:04:25,510 What am I going to do with this? 55 00:04:25,540 --> 00:04:28,120 Well, let's go back to our main file. 56 00:04:29,920 --> 00:04:34,180 May not go and down in the run function. 57 00:04:35,240 --> 00:04:37,180 I want to initialize my database here. 58 00:04:37,270 --> 00:04:39,550 I want to actually initialize my database repo. 59 00:04:39,550 --> 00:04:41,190 And I can do that pretty easily. 60 00:04:41,590 --> 00:04:51,640 I could say right after this Aptos session, I can just say connect to a database and what am I going 61 00:04:51,640 --> 00:04:51,970 to do? 62 00:04:52,090 --> 00:05:01,510 I'll write to the terminal log print line connecting to the database just to get some feedback and then 63 00:05:01,510 --> 00:05:02,380 actually do the connection. 64 00:05:04,200 --> 00:05:10,530 So I will call DB error, I'm going to get my connection pool and I get that from my driver package 65 00:05:10,530 --> 00:05:12,270 that we created in the last lecture. 66 00:05:12,960 --> 00:05:14,900 And the math on that is Connect sequel. 67 00:05:14,910 --> 00:05:17,420 And then we have our DSN and our DSN. 68 00:05:17,430 --> 00:05:18,720 I'm going to hardcoded right now. 69 00:05:18,720 --> 00:05:21,110 We'll change that before we're finished with this project. 70 00:05:21,120 --> 00:05:23,280 But right now I'm just going to hardcoded just to get it working. 71 00:05:23,580 --> 00:05:26,850 So we'll do it just like we did in our last hour. 72 00:05:27,090 --> 00:05:34,140 Test database application post equals localhost port equals five, four, three, two. 73 00:05:35,100 --> 00:05:38,280 DB name is equal to bookings. 74 00:05:39,010 --> 00:05:40,020 I think that's what I called it. 75 00:05:40,200 --> 00:05:41,060 We'll find out in a minute. 76 00:05:41,730 --> 00:05:47,340 User equals ticks and of course your username will be different and my password is currently empty. 77 00:05:47,340 --> 00:05:50,850 So I'll just put a password in that I can leave it out, but eventually you're going to be connecting 78 00:05:50,850 --> 00:05:52,260 to a database that has a password. 79 00:05:52,260 --> 00:05:54,720 So we may as well take that into account right now. 80 00:05:55,590 --> 00:05:56,730 So that will do our connection. 81 00:05:56,730 --> 00:05:57,960 Then we test for our error. 82 00:05:57,990 --> 00:06:00,930 If error is not equal to nil, what do I want to do? 83 00:06:00,930 --> 00:06:06,480 I'll I'll just log fatele because if I can't connect to my database, bad things are happening and I'll 84 00:06:06,480 --> 00:06:07,470 print the message. 85 00:06:07,620 --> 00:06:15,030 Cannot connect to database dying because I'll die with that log fail. 86 00:06:15,780 --> 00:06:19,500 Now that I have this connected, I have my database connection pool. 87 00:06:19,530 --> 00:06:20,510 What am I going to do with it? 88 00:06:21,030 --> 00:06:25,290 Well, if you recall, one of the things that I said we should do is close it when we're done with it 89 00:06:25,290 --> 00:06:34,680 so I could write deferred DB Forclose DB dot SQL close. 90 00:06:35,520 --> 00:06:37,370 But if I do that, what's going to happen? 91 00:06:38,010 --> 00:06:42,300 I'm actually in a function called Run, which is called up here. 92 00:06:42,510 --> 00:06:44,730 Very first thing I do in my main function is call that. 93 00:06:45,180 --> 00:06:52,500 So if I open my connection to the database and then put defer close and then the run function is finished, 94 00:06:52,920 --> 00:06:59,190 it will close the database connections immediately after the run finishes, which you know is no good 95 00:06:59,190 --> 00:07:02,070 because I'll close my database connections right after opening them. 96 00:07:02,370 --> 00:07:03,650 So that's not going to be helpful. 97 00:07:04,050 --> 00:07:10,710 So what I need to do instead is have this not here, take it out and have this run function return more 98 00:07:10,710 --> 00:07:11,700 than a potential error. 99 00:07:11,970 --> 00:07:13,380 So I'll have it return. 100 00:07:13,980 --> 00:07:15,240 What shall I have it return. 101 00:07:15,240 --> 00:07:16,290 I shall have a return. 102 00:07:16,290 --> 00:07:21,570 My driver DB So it's a pointer to driver DB and an error. 103 00:07:22,630 --> 00:07:25,440 So now I got a few things to fix down here. 104 00:07:25,440 --> 00:07:26,820 I can't return nothing. 105 00:07:27,180 --> 00:07:28,080 Return just the air. 106 00:07:28,080 --> 00:07:30,350 I have to return nil in the error because I couldn't create it. 107 00:07:30,510 --> 00:07:39,030 Just die at this point and down here I'll return my DB so that will take care of the errors for the 108 00:07:39,030 --> 00:07:39,780 run function. 109 00:07:40,260 --> 00:07:44,460 But up here I can't just er have er equals run. 110 00:07:44,460 --> 00:07:53,520 Instead I say db and error equals run and I'm not using DB right now, but if I get past this then I 111 00:07:53,520 --> 00:08:03,390 want to defer DB sequel Duclos and now the database connection won't be closed until the main function 112 00:08:03,600 --> 00:08:06,720 itself stops running, which means the application is stopped. 113 00:08:06,720 --> 00:08:07,610 So that's very good. 114 00:08:08,100 --> 00:08:13,980 So I've actually got this database connection right now, but I'm not doing anything with it and I need 115 00:08:13,980 --> 00:08:14,940 to do something with it. 116 00:08:14,940 --> 00:08:16,550 So what shall I do with it? 117 00:08:17,430 --> 00:08:19,140 Well, back down here in the run function. 118 00:08:21,030 --> 00:08:27,060 I need to ensure that my database connection is available and certainly to my handlers, possibly something 119 00:08:27,060 --> 00:08:28,950 else, but certainly to my handlers. 120 00:08:29,610 --> 00:08:36,940 So over in our handlers, what I'm going to do is change this repository and have it hold another repository. 121 00:08:37,500 --> 00:08:39,260 So what am I going to put in here? 122 00:08:39,840 --> 00:08:48,600 I call it DBI because of the database connection and it's a type repository that, again, repository 123 00:08:50,190 --> 00:08:51,060 database repo. 124 00:08:52,050 --> 00:08:58,580 And down here I'll actually accept a second parameter and it will not be a repository. 125 00:08:58,740 --> 00:09:06,270 It will instead be a DB, which is a pointer to driver DB and I'll have to pass that in the main function. 126 00:09:06,270 --> 00:09:07,090 But we'll do that in a minute. 127 00:09:08,010 --> 00:09:13,890 And now I will populate my DB repository, not with DB because it's not a repository. 128 00:09:13,890 --> 00:09:15,530 That's a pointer to driver DB. 129 00:09:15,540 --> 00:09:21,080 Instead, I'll call that new pupi new postgrads repo function that I made in my DB Repo Golfo. 130 00:09:21,330 --> 00:09:23,460 So I call DB Repo. 131 00:09:26,890 --> 00:09:36,910 Debbie Repo new postcrisis repo, and it requires our connection, which is Debe, and it requires our 132 00:09:37,330 --> 00:09:37,790 config. 133 00:09:37,870 --> 00:09:38,870 So put that in there as well. 134 00:09:39,130 --> 00:09:41,080 Probably don't need up config there, but it's not going to hurt. 135 00:09:41,710 --> 00:09:44,760 It's not DIVI, it's DB DOT sequel there. 136 00:09:45,430 --> 00:09:46,850 Now that matches the correct type. 137 00:09:47,560 --> 00:09:53,080 So what I've done here, when I call New Repo, I'm going to pass it my app config, which is a pointer 138 00:09:53,080 --> 00:09:54,280 to configure config. 139 00:09:54,280 --> 00:09:58,900 I'm going to pass it in my database connection pool, which is a pointer to Driver DB which holds my 140 00:09:58,900 --> 00:10:00,010 database connection pool. 141 00:10:00,400 --> 00:10:07,030 And then I populate this repository type up here with all the information I received as parameters and 142 00:10:07,030 --> 00:10:08,910 hand that back as a pointer to repository. 143 00:10:09,400 --> 00:10:11,290 So I've created that. 144 00:10:11,650 --> 00:10:15,460 Now we need to go back to our main function and you'll discover that we have an error. 145 00:10:15,460 --> 00:10:23,760 And the error is I need to pass that second parameter, which is DB, and that should create our repository. 146 00:10:24,100 --> 00:10:29,560 So with that one change, I think about what I've done here, I've now created this handlock, this 147 00:10:29,560 --> 00:10:31,450 repo that I'm going to use in my handlers. 148 00:10:31,900 --> 00:10:37,120 We have our application config available to all of our handlers and we can put whatever we want in there. 149 00:10:37,600 --> 00:10:38,830 And we've also passed it. 150 00:10:38,830 --> 00:10:43,920 This DB, which is not a database connection pool tied to a specific database. 151 00:10:44,230 --> 00:10:46,120 Instead, it's a pointer to a driver. 152 00:10:46,330 --> 00:10:50,050 And that driver can right now only handle postgrads. 153 00:10:50,290 --> 00:10:58,480 But I can very easily, just by creating a new instance, a new a new function instead of new my new 154 00:10:58,480 --> 00:11:04,970 postgrads, I can create a new MySQL function so I can have this repository for the handlers, hold 155 00:11:04,990 --> 00:11:13,080 a repository that's of a type for Postgrads or MySQL or Oracle of Mongo DB or whatever I want. 156 00:11:13,330 --> 00:11:15,130 Now let's see how this is all going to work. 157 00:11:16,150 --> 00:11:22,270 You recall a little while ago, first of all, let's make sure this runs and run my application. 158 00:11:23,660 --> 00:11:24,610 Okay, compile. 159 00:11:24,610 --> 00:11:25,090 That's good. 160 00:11:25,240 --> 00:11:30,910 I'm going to put one more log in there just to say that I actually connected to the database. 161 00:11:30,910 --> 00:11:35,830 So log print line connected to database. 162 00:11:36,820 --> 00:11:37,150 All right. 163 00:11:37,160 --> 00:11:44,140 Again, just to get some feedback, so I'll clear the screen and run it again and everything past. 164 00:11:44,140 --> 00:11:44,490 Good. 165 00:11:44,530 --> 00:11:45,000 All right. 166 00:11:45,670 --> 00:11:48,610 So now that I've done this, how can I use it? 167 00:11:48,610 --> 00:11:56,560 How can I put some methods or some functions available to this repository for the database that I've 168 00:11:56,560 --> 00:11:57,810 created and passed right here? 169 00:11:58,150 --> 00:12:00,070 How can I actually use some functions in there? 170 00:12:00,100 --> 00:12:04,690 Well, you may recall we have this interface that's of type database. 171 00:12:04,690 --> 00:12:06,580 It's a type database repo. 172 00:12:06,580 --> 00:12:07,450 That's an interface. 173 00:12:07,720 --> 00:12:14,140 I'm going to create another file inside of the DB repo folder and I'm going to call it Postcrisis Dargo. 174 00:12:14,350 --> 00:12:20,140 And here is where I will put any functions that I want to be available to that interface. 175 00:12:20,140 --> 00:12:25,360 So I'll create a function, I'll call it, and it has to have a receiver and I'll call the receiver 176 00:12:25,570 --> 00:12:26,110 for model. 177 00:12:26,350 --> 00:12:32,140 And it's a type postgrads DB repo which links it to my postgrads repository and I'll call it all users. 178 00:12:32,920 --> 00:12:36,150 And it's right now it's not going to take any parameters and it's just going to return a bool. 179 00:12:37,750 --> 00:12:38,650 This is going to change. 180 00:12:38,650 --> 00:12:40,960 This is just to show you how it works and I'll just have this return. 181 00:12:40,960 --> 00:12:41,290 True. 182 00:12:42,460 --> 00:12:49,120 So I've defined this all users function that has a receiver of postgrads DB repo. 183 00:12:49,130 --> 00:12:54,910 So what I'm going to do is copy the function name and its return type and I'll paste it right into my 184 00:12:54,910 --> 00:12:55,630 repository. 185 00:12:56,620 --> 00:13:02,830 Now that I've done that, now that this function is listed in the interface and the function exists 186 00:13:03,280 --> 00:13:10,090 with a receiver of postgrads DB repo and the function exists exists exactly as it's defined in the interface. 187 00:13:10,300 --> 00:13:15,370 Now I can go to my handlers and I can choose any handler, say, the home function, for example. 188 00:13:16,000 --> 00:13:22,690 And on that repository, I don't have access to the DB and I can call all users. 189 00:13:23,380 --> 00:13:30,760 And that is really, really cool and very useful because all I have to do what I want to add new functionality 190 00:13:30,760 --> 00:13:35,170 to that, be a member of the repository. 191 00:13:35,530 --> 00:13:37,210 I'll get rid of this because we're not going to use it here. 192 00:13:38,170 --> 00:13:45,340 All I have to do is defined my function in here with this receiver and add it to the repository. 193 00:13:45,490 --> 00:13:50,230 And I have access to all of my database functions which will be writing in the in the coming lectures. 194 00:13:50,560 --> 00:13:57,670 I have access to all of them right in my handlers just because I created that repository that holds 195 00:13:57,670 --> 00:13:58,900 a database repository. 196 00:13:59,530 --> 00:13:59,980 All right. 197 00:14:00,190 --> 00:14:05,140 So in the next few lectures, we'll start thinking about what we need to be able to do in our database, 198 00:14:05,290 --> 00:14:08,860 and we'll write some functions and then we'll update our handlers to use those functions. 199 00:14:09,070 --> 00:14:09,820 We're getting closer.