1 00:00:00,780 --> 00:00:07,500 So let's write a few routines to add records to or delete records from or get records from the database, 2 00:00:07,800 --> 00:00:10,150 and let's think about the first one we want to do. 3 00:00:10,200 --> 00:00:11,580 So I'm going to start the application. 4 00:00:11,580 --> 00:00:12,370 So I'm running it. 5 00:00:13,620 --> 00:00:15,770 We're now running the application is running. 6 00:00:15,780 --> 00:00:17,490 Let's go to the application. 7 00:00:18,210 --> 00:00:19,740 Localhost 880. 8 00:00:24,570 --> 00:00:26,670 So what are some things I'm going to need to do here? 9 00:00:26,700 --> 00:00:31,810 Well, obviously book now is one that I want to do and I would do my search for availability. 10 00:00:31,830 --> 00:00:32,710 We'll do that one later. 11 00:00:33,060 --> 00:00:34,500 Right now, let's just do a simple one. 12 00:00:34,560 --> 00:00:36,800 Let's go to the Make Reservation page. 13 00:00:37,860 --> 00:00:43,050 Here is a page where I am going to be posting some information and saving it to the database. 14 00:00:43,320 --> 00:00:48,690 And there are things that I know I'm going to have basically when I look at my database structure by 15 00:00:48,690 --> 00:00:49,710 opening the model. 16 00:00:51,510 --> 00:01:00,870 So internal models, models and a reservation, everything down to here, all of this stuff needs to 17 00:01:00,870 --> 00:01:02,350 be saved to the database. 18 00:01:02,400 --> 00:01:08,730 This one room, which is actually a remodel, is not part of the database table for reservation, which 19 00:01:08,730 --> 00:01:09,900 is called reservations. 20 00:01:09,930 --> 00:01:16,710 So I need to be able to post information to my handler, pass it off to a database function and write 21 00:01:16,710 --> 00:01:18,330 that reservation to the database. 22 00:01:18,360 --> 00:01:19,490 So let's do that one first. 23 00:01:19,980 --> 00:01:28,320 So I'm going to go back to my repository package inside DB repoll and open postcards, and I'm also 24 00:01:28,320 --> 00:01:30,000 going to open the repository files. 25 00:01:30,000 --> 00:01:34,080 So let's do this first will leave the all users there will come back and do something with that later 26 00:01:34,080 --> 00:01:34,620 and clean it up. 27 00:01:35,010 --> 00:01:40,890 But let's just write a routine that's going to write a reservation to the database. 28 00:01:41,280 --> 00:01:47,760 So maybe I can just call that insert reservation and that will be a function that's going to take some 29 00:01:47,760 --> 00:01:48,270 arguments. 30 00:01:48,510 --> 00:01:54,030 And I could if I wanted to have one argument for every one of these things, but that would make for 31 00:01:54,030 --> 00:01:55,310 a very long function. 32 00:01:55,320 --> 00:02:00,360 So I'll have to put every one of those in as a parameter, it seems to me would make more sense to pass 33 00:02:00,630 --> 00:02:06,200 a rez of type models reservation and return. 34 00:02:06,570 --> 00:02:10,140 There's maybe one thing I'm going to return here, an error potentially. 35 00:02:10,400 --> 00:02:11,690 OK, so now what? 36 00:02:11,700 --> 00:02:14,030 I've added that to the repository. 37 00:02:14,640 --> 00:02:16,650 Watch what happens when I try to run the application. 38 00:02:16,770 --> 00:02:22,650 So I stop this there the screen and say run and it's going to fail and it's going to fail because this 39 00:02:22,650 --> 00:02:28,710 is an interface and an interface is actually a contract that says, hey, if you're going to implement 40 00:02:28,710 --> 00:02:33,480 this interface, which can go, you do by satisfying all of the necessary functions. 41 00:02:33,840 --> 00:02:41,100 Well, my package, as it says right here in the error message, the type postgrads DB repo doesn't 42 00:02:41,100 --> 00:02:43,970 implement the insert reservation method. 43 00:02:44,040 --> 00:02:46,000 So we have to do that before we can compile it. 44 00:02:46,020 --> 00:02:53,700 So just to make the program compiler able, let's go over here to our functions and say func M Postgrads 45 00:02:53,700 --> 00:03:01,020 Repo Postcards, DB Repo insert reservation and that will take a raise which is of type models thought 46 00:03:01,020 --> 00:03:07,260 reservation and it will return an error or nil if there's no error and we just say return nil. 47 00:03:08,400 --> 00:03:12,690 And now that we've done this, even though we're not doing anything in this function, if I try to run 48 00:03:12,690 --> 00:03:13,620 the program again. 49 00:03:17,510 --> 00:03:20,070 Now it runs with no errors, so there you go. 50 00:03:20,300 --> 00:03:21,910 That is an important thing to know. 51 00:03:21,920 --> 00:03:27,140 You can't put functions in here and expect to have them available if you put it in postgrads. 52 00:03:27,140 --> 00:03:33,530 Don't expect us to have a have this available to your application until you add its description to the 53 00:03:33,530 --> 00:03:34,970 database repo interface. 54 00:03:35,030 --> 00:03:38,210 OK, so what are we going to do in this function? 55 00:03:38,240 --> 00:03:40,700 Well, we're going to have to obviously write a query, right? 56 00:03:40,700 --> 00:03:44,630 So I'll write a query, but I'll call it a statement because I'm inserting something into the database 57 00:03:44,930 --> 00:03:48,290 and that's going to be equal to insert into. 58 00:03:48,470 --> 00:03:50,010 And what table in my answer to get into. 59 00:03:50,030 --> 00:03:51,520 Well, let's have a look at our database structure. 60 00:03:51,920 --> 00:03:59,120 We're inserting it into reservations, resins, derivations, and then describe the field you're going 61 00:03:59,120 --> 00:03:59,510 to enter. 62 00:03:59,510 --> 00:04:08,750 So I'm going to enter first name, last name, email and phone, first name, last name, email, phone, 63 00:04:11,030 --> 00:04:14,690 start date and date, relighting start date. 64 00:04:14,690 --> 00:04:15,770 And I'll just go to the next line. 65 00:04:20,470 --> 00:04:26,470 End date, start date and date remedy created updated. 66 00:04:26,890 --> 00:04:28,210 I got to have a comma here to. 67 00:04:30,860 --> 00:04:42,830 Room I'd created at, updated at and then on the next line, I'll go with values and I'll use my placeholders. 68 00:04:42,830 --> 00:04:44,390 Dollar sign, one dollar sign. 69 00:04:46,820 --> 00:04:47,830 Two, how many are there? 70 00:04:47,870 --> 00:04:54,530 One, two, three, four, five, six, seven, eight, nine dollar sign. 71 00:04:57,530 --> 00:05:05,330 Three dollar sign for dollar sign, five dollar signs, six dollar signs, seven dollar sign, eight 72 00:05:06,050 --> 00:05:09,890 dollar sign nine, and then I have to close the parentheses. 73 00:05:10,080 --> 00:05:12,070 OK, so there's my statement. 74 00:05:12,680 --> 00:05:15,320 Now, how do I actually execute that statement? 75 00:05:15,950 --> 00:05:23,000 Well, last time around when we were inserting things into the database, we used the exact exact function 76 00:05:23,000 --> 00:05:28,130 so I could actually just say if I wanted to m db dot exactly. 77 00:05:28,790 --> 00:05:35,030 And then put in my statement and passing all of the arguments and I'm going to put them on separate 78 00:05:35,030 --> 00:05:36,990 lines just to make this more readable, OK. 79 00:05:37,790 --> 00:05:47,630 So my my first name would be read first name, my last name would be read last name and then Rezo email. 80 00:05:49,010 --> 00:06:02,360 Resident phone rings resident start date resident Endi and resident remedy 81 00:06:04,910 --> 00:06:06,850 and resident created at will. 82 00:06:06,890 --> 00:06:09,290 If you don't want to bother doing that, I can if I want to. 83 00:06:09,290 --> 00:06:12,680 But all I really care about what I'm asserting is the current time and date. 84 00:06:12,680 --> 00:06:17,030 So I can just say time now and time dot now. 85 00:06:17,600 --> 00:06:22,670 Oops, not a nanosecond now and that will take care of it. 86 00:06:23,350 --> 00:06:24,710 What's this underlined for. 87 00:06:24,890 --> 00:06:26,300 No, that's just an irritating thing. 88 00:06:26,300 --> 00:06:30,890 If you don't like that underlining of the school like I don't you can get rid of it by going to goaland 89 00:06:31,220 --> 00:06:40,070 if you're using goaland preferences and look for sequel school and summer here you'll find inspection's 90 00:06:40,610 --> 00:06:49,580 where are inspections and look for school and just uncheck all sequels like that and say apply and OK, 91 00:06:50,870 --> 00:06:53,720 because Goaland is trying to connect to my database itself. 92 00:06:53,720 --> 00:06:54,920 I don't want it too. 93 00:06:55,340 --> 00:06:59,990 So I just say, don't bother telling me about the fact that you can't connect to the database. 94 00:07:00,080 --> 00:07:01,570 That's just an aside. 95 00:07:01,910 --> 00:07:03,050 Now, this will actually work. 96 00:07:03,230 --> 00:07:04,910 I can I can actually do this. 97 00:07:05,150 --> 00:07:09,650 And of course, when I call this, I'm getting a result and an error. 98 00:07:09,680 --> 00:07:16,310 I can ignore the result if I want to and just say error is assigned and then trap for an error. 99 00:07:17,030 --> 00:07:25,550 If error is not equal to nil return error and that will actually work, there's no problem with that 100 00:07:25,550 --> 00:07:26,210 whatsoever. 101 00:07:27,270 --> 00:07:35,670 However, we're in a Web application and Web applications are unpredictable in one sense, for example, 102 00:07:36,120 --> 00:07:40,910 the user might lose his or her connection to the Internet partway through this transaction. 103 00:07:41,580 --> 00:07:43,080 And what happens then? 104 00:07:43,620 --> 00:07:48,420 The user might just close their browser without warning in the midst of something that's taking place 105 00:07:48,420 --> 00:07:49,810 with the database in the background. 106 00:07:50,220 --> 00:07:55,980 So what we can do, what we want to have happen here, as we want to make sure that this transaction 107 00:07:55,980 --> 00:08:01,760 doesn't stay open for the five minute lifetime that we have for transactions if nothing is happening. 108 00:08:02,310 --> 00:08:07,410 So I'm going to take advantage of the context, something that was built in to go right around, go 109 00:08:07,410 --> 00:08:08,610 one point eight, I think it was. 110 00:08:09,300 --> 00:08:10,740 And it's called the context. 111 00:08:10,740 --> 00:08:18,150 And we do that by at the very top of our function doing this context and cancel because I want to cancel 112 00:08:18,150 --> 00:08:19,020 my context. 113 00:08:19,320 --> 00:08:25,710 If something goes wrong, that's a sign, the value of context with time out. 114 00:08:26,930 --> 00:08:33,060 OK, context with time out, and I'm going to pass it, a context that is always available anywhere 115 00:08:33,060 --> 00:08:40,130 in your application called context dot background, and I'm going to give it a timeout and I'm going 116 00:08:40,130 --> 00:08:46,820 to say, if this transaction takes longer than X number of seconds, DI, just cancel it and send a 117 00:08:46,820 --> 00:08:49,100 capsule back and everything will go back to where it should be. 118 00:08:49,580 --> 00:08:55,640 And I think that for our purposes, if you can't insert this transaction in three seconds, something 119 00:08:55,640 --> 00:08:57,520 is seriously wrong with our application. 120 00:08:57,530 --> 00:08:59,950 So I'll say three times time. 121 00:09:00,230 --> 00:09:04,170 Second, which gives this a three second timeout. 122 00:09:04,430 --> 00:09:09,020 OK, so now that this is here, I need to say defer. 123 00:09:09,530 --> 00:09:10,010 Cancel. 124 00:09:12,340 --> 00:09:18,160 That's all I need to do, except I'm not using this right now, because exactly this function is built 125 00:09:18,160 --> 00:09:19,270 into the database package. 126 00:09:19,660 --> 00:09:25,230 It doesn't know anything about context whatsoever, but this one does exact context. 127 00:09:26,920 --> 00:09:31,330 So if I do that, the first argument is actually the context that I declared at the very beginning of 128 00:09:31,330 --> 00:09:31,870 this function. 129 00:09:32,440 --> 00:09:37,360 Now I have a much safer and more robust means of talking to the database. 130 00:09:37,540 --> 00:09:42,640 So with virtually identical to what we did in our first experiments with the database, the only difference 131 00:09:42,640 --> 00:09:47,810 is instead of calling exactly what I call exact context, and that's true for the other methods, for 132 00:09:47,870 --> 00:09:51,170 ones, for updating and deleting, we can use the context there as well. 133 00:09:51,850 --> 00:09:56,170 So I now have this function called insert reservation and I'll better give it a comment. 134 00:09:57,550 --> 00:10:01,690 Inserts a reservation into the database. 135 00:10:02,920 --> 00:10:06,160 We now have a means of storing it and that is extremely helpful. 136 00:10:06,250 --> 00:10:15,550 So we can go back to our handler now and find the handler that does post reservation right here. 137 00:10:16,480 --> 00:10:20,150 And instead of just building this, we're going to have to change our form. 138 00:10:20,170 --> 00:10:22,690 I'm also going to want the start date, the end date. 139 00:10:22,690 --> 00:10:24,790 And what other information am I putting in there? 140 00:10:24,820 --> 00:10:25,870 I can't remember now. 141 00:10:27,670 --> 00:10:29,830 So we have the first name, last name, email, phone. 142 00:10:29,830 --> 00:10:32,140 We need the start date, the end date and the room ID. 143 00:10:32,380 --> 00:10:36,640 The other two are created with our time now, which you shouldn't search the current date and time into 144 00:10:36,640 --> 00:10:36,760 it. 145 00:10:37,090 --> 00:10:38,440 So we'll have to change our form. 146 00:10:38,470 --> 00:10:39,550 We can do that afterwards. 147 00:10:39,550 --> 00:10:40,590 Let's just fix our handler. 148 00:10:41,080 --> 00:10:43,900 So start date and end date, OK? 149 00:10:43,930 --> 00:10:51,310 Now these are a little bit different because we're receiving our date as a string and we need to convert 150 00:10:51,310 --> 00:10:53,680 it into the format that our model expects. 151 00:10:53,710 --> 00:11:02,410 For example, if I try this, if I just say start date is ARG form doget start date, which doesn't 152 00:11:02,410 --> 00:11:02,890 exist yet. 153 00:11:02,890 --> 00:11:05,010 But it will it's going to it's going to die. 154 00:11:05,020 --> 00:11:06,610 It says, well, hang on a second here. 155 00:11:06,820 --> 00:11:12,730 Cannot use our form arget start date, which is type string as tight time dot time. 156 00:11:13,150 --> 00:11:17,770 So what I need to do is get our start date and end date which I can do. 157 00:11:17,770 --> 00:11:24,910 Like this SSD is a sign the value of that and ID for end date is a sign the value of end date. 158 00:11:25,690 --> 00:11:32,260 I can store those strings right here and then I need to cast those strings over to a time. 159 00:11:32,530 --> 00:11:34,360 Time now. 160 00:11:34,360 --> 00:11:38,350 One of the things that I know I'm going to get my date formatted is going to come something like this 161 00:11:38,350 --> 00:11:40,000 20-20 zero one zero one. 162 00:11:40,360 --> 00:11:44,560 That will be the format that I get my date in my starting date. 163 00:11:44,560 --> 00:11:53,530 Am I end it the way that Go handles dates and times is a little unusual and it might seem a little non-intuitive 164 00:11:53,530 --> 00:11:53,950 at first. 165 00:11:53,960 --> 00:11:57,970 Certainly I have to look this up almost every time I go back and work with dates. 166 00:11:58,570 --> 00:12:04,690 So let me go over to my Web browser or I have open this blog post and I'll put a cop up, post a link 167 00:12:04,690 --> 00:12:07,650 to this right on to the resources for this page. 168 00:12:08,410 --> 00:12:15,460 This is how you pass and format dates and times Engo and if you look at it go takes an interesting approach 169 00:12:15,460 --> 00:12:18,910 to parsing strings to time objects and formatting objects at strings. 170 00:12:18,910 --> 00:12:25,240 And you can follow that link and it gives an example there, but it uses a non-standard reference time 171 00:12:25,240 --> 00:12:26,050 engo. 172 00:12:26,230 --> 00:12:33,160 The reference date and time are Monday, January the 2nd, at four minutes and five seconds after three 173 00:12:33,160 --> 00:12:37,450 o'clock in the afternoon Mountain Standard Time in the year 2006. 174 00:12:38,170 --> 00:12:43,960 And the reason they've gone with this is because using the standard method of writing dates in America, 175 00:12:44,140 --> 00:12:53,980 it goes as follows zero one zero two zero three zero four 05 06 for 2006 and minus seven GMT for Mountain 176 00:12:53,980 --> 00:12:54,670 Standard Time. 177 00:12:54,940 --> 00:12:57,520 And apparently that's an easy way to remember dates. 178 00:12:57,520 --> 00:12:58,810 It might be for other people. 179 00:12:58,810 --> 00:12:59,590 It's not for me. 180 00:12:59,620 --> 00:13:03,520 I have to look it up every time, so don't feel bad if you have to look it up as well. 181 00:13:05,590 --> 00:13:11,140 Now, to convert our string to a time, it's a relatively straightforward approach once you know the 182 00:13:11,140 --> 00:13:11,560 format. 183 00:13:11,560 --> 00:13:19,780 So I'm going to copy this format here like this and just paste it in my comment like this so I have 184 00:13:19,780 --> 00:13:21,010 a reference to it, OK? 185 00:13:21,700 --> 00:13:28,870 And I need to do what I need to do is to describe the format that my date is coming in, using this 186 00:13:28,870 --> 00:13:30,010 as a kind of reference. 187 00:13:30,010 --> 00:13:32,560 OK, so I can do it as follows. 188 00:13:32,560 --> 00:13:39,010 What I'm going to do is describe a layout and the layout will be a string that describes my date format 189 00:13:39,400 --> 00:13:42,130 and the format I'm getting my date in. 190 00:13:42,130 --> 00:13:48,940 The string that I'm receiving from my form will be in the form of the year and a half to use 2006 as 191 00:13:48,940 --> 00:13:55,450 a reference here, followed by the month, which is zero one in the reference time, followed by the 192 00:13:55,450 --> 00:13:57,900 date, which is zero two in reference time. 193 00:13:57,910 --> 00:14:00,430 That's the format I'm getting my date in. 194 00:14:00,550 --> 00:14:08,140 OK, now I want to pass SD and ID from what they are into times and I can do that as follows. 195 00:14:08,170 --> 00:14:10,240 I can just say start. 196 00:14:10,470 --> 00:14:22,230 Date and then potentially an error is assigned the value of time, don't pass my layout and the date 197 00:14:22,230 --> 00:14:28,790 I want to pass, which is SD for start date, OK, and I can do the same thing for end date. 198 00:14:30,460 --> 00:14:36,070 But it's not start date, this case, it's ended up passing and then need to for my errors, if error 199 00:14:36,070 --> 00:14:39,040 is not equal to nil, then what do I want to do? 200 00:14:39,040 --> 00:14:43,180 Helper's dot server error and an error. 201 00:14:43,480 --> 00:14:46,480 So I'll just call my server error and the same thing here. 202 00:14:50,110 --> 00:14:58,120 Now that I have the start date and end date, I can actually populate my model with start date and end 203 00:14:58,120 --> 00:14:58,330 date. 204 00:15:00,620 --> 00:15:01,390 Which will be ended. 205 00:15:03,890 --> 00:15:12,350 OK, the last thing I need is my remedy and again, remedy in our model is actually an INT, so I need 206 00:15:12,350 --> 00:15:14,630 to convert what I'm going to get from the form. 207 00:15:14,630 --> 00:15:16,550 And I'm not passing that yet and I'm aware of it. 208 00:15:17,390 --> 00:15:19,790 I need to convert that from a string into an ENT. 209 00:15:19,970 --> 00:15:21,440 That's again, not that difficult. 210 00:15:21,440 --> 00:15:28,880 So I can just say room ID is assigned and er potentially an error is assigned the value of and I use 211 00:15:28,880 --> 00:15:38,480 a built in package as part of the standard library sirc invis sterkel a for alpha to integer and the 212 00:15:38,480 --> 00:15:44,690 string and the string I'll get from my form as adon form dot get room ID. 213 00:15:44,960 --> 00:15:47,420 I'll assume that's going to be the name of the parameter the past. 214 00:15:47,420 --> 00:15:51,980 Just as I'm assuming the name of the parameter I'm going to get for start date is start underscore date 215 00:15:51,980 --> 00:15:53,540 and end date and underscore date. 216 00:15:53,900 --> 00:15:56,990 Once I have this I get an idea from my error. 217 00:15:58,760 --> 00:16:05,120 Once I have this I could use my remedy like this room ID is remedy. 218 00:16:06,440 --> 00:16:06,830 All right. 219 00:16:06,830 --> 00:16:13,970 Now that I've built this reservation model, what I actually want to do is after my form validation, 220 00:16:13,970 --> 00:16:19,220 making sure all of this is accurate, after my form validation, I actually want to write this information 221 00:16:19,220 --> 00:16:27,560 to the database and I can do that by going m db dot insert reservation and passing in my reservation, 222 00:16:27,560 --> 00:16:28,940 which I called reservation. 223 00:16:33,410 --> 00:16:36,110 And of course this handles an error to us. 224 00:16:36,140 --> 00:16:37,550 So I can say error equals. 225 00:16:40,520 --> 00:16:52,130 If error is not equal to nil, then helper's that server error W and hair and that while she said that 226 00:16:52,140 --> 00:16:58,310 to our database, so we can't test this until we actually go update our form, but we can do that and 227 00:16:58,310 --> 00:17:02,750 we'll do it and we'll just put some some default values in there to make sure that it's working the 228 00:17:02,750 --> 00:17:03,320 way we want. 229 00:17:03,740 --> 00:17:06,410 And we'll test that and we'll do that in the next lecture.