1
00:00:00,025 --> 00:00:06,821
[NOISE] So
let's keep moving on our project.

2
00:00:06,821 --> 00:00:11,110
I find that working on the model is
a great way to shake out a prototype.

3
00:00:11,110 --> 00:00:13,910
So let's think through our problem a bit.

4
00:00:13,910 --> 00:00:17,340
We obviously need to have an idea,
which has a title.

5
00:00:17,340 --> 00:00:19,440
And the idea'll also have a creator.

6
00:00:19,440 --> 00:00:22,290
Now, we'll worry about how to
keep track of votes in a bit.

7
00:00:22,290 --> 00:00:25,948
First, let's create the ability to
add ideas and then retrieve them.

8
00:00:25,948 --> 00:00:29,925
Now, to me, that sounds like we
need to store things somewhere.

9
00:00:29,925 --> 00:00:34,450
I mean, what we wanna do is make it so
that even if our web server restarts,

10
00:00:34,450 --> 00:00:37,730
that our data is saved someplace,
or persistent.

11
00:00:37,730 --> 00:00:40,010
That's a little out of scope for
this project, though, so

12
00:00:40,010 --> 00:00:42,030
check the teacher's notes for more info.

13
00:00:42,030 --> 00:00:43,110
So let's do this.

14
00:00:43,110 --> 00:00:44,600
Let's use an interface and

15
00:00:44,600 --> 00:00:48,770
we'll build a prototype implementation
that just uses normal data structures.

16
00:00:48,770 --> 00:00:49,660
Sound good?

17
00:00:49,660 --> 00:00:53,020
That way, later we can swap out
a database implementation or

18
00:00:53,020 --> 00:00:53,910
anything for that matter.

19
00:00:53,910 --> 00:00:57,380
As long as it meets our contract,
we'll be good to go.

20
00:00:57,380 --> 00:01:01,370
That seems like a pretty light way to
do things in its micro framework land.

21
00:01:01,370 --> 00:01:05,420
Now, larger frameworks provide some of
this capability out of the box, but our

22
00:01:05,420 --> 00:01:09,650
micro framework here doesn't necessarily
force us into any direction at all.

23
00:01:09,650 --> 00:01:13,855
So what do you say we drop that contract.

24
00:01:13,855 --> 00:01:17,120
So let's make a new class.

25
00:01:17,120 --> 00:01:18,700
And we're gonna put it in a new package.

26
00:01:19,930 --> 00:01:28,648
So we're gonna say model.Courseidea.

27
00:01:28,648 --> 00:01:32,840
And this is where we will store
the data structure basically.

28
00:01:32,840 --> 00:01:39,440
So we said that this is gonna have
a string [BLANK AUDIO] called title,

29
00:01:39,440 --> 00:01:45,510
and we also said it's gonna have
a private string called creator.

30
00:01:45,510 --> 00:01:50,825
So let's go ahead and we'll generate,
remember that was Cmd+N,

31
00:01:50,825 --> 00:01:54,740
we're gonna generate the constructor.

32
00:01:54,740 --> 00:01:56,070
And then, we'll take both of those.

33
00:01:57,130 --> 00:02:01,870
Title and creator and while we're at it,
let's do another generation.

34
00:02:01,870 --> 00:02:05,476
Let's generate some getters.

35
00:02:10,424 --> 00:02:16,594
And while we're here, let's go ahead and
let's generate the equals and hashCode.

36
00:02:16,594 --> 00:02:17,991
I'll just use the default one.

37
00:02:20,225 --> 00:02:21,313
Great.

38
00:02:22,468 --> 00:02:25,010
Made you type all that stuff out?

39
00:02:25,010 --> 00:02:26,859
Sorry about that.

40
00:02:26,859 --> 00:02:31,354
Now, the simplest way to get where we're
headed is to have a single interface that

41
00:02:31,354 --> 00:02:34,010
accesses all we need data storage wise.

42
00:02:34,010 --> 00:02:36,370
So let's build it and we'll talk about it.

43
00:02:36,370 --> 00:02:40,720
So a commonly recognized way of naming
the way that you plan to access the data

44
00:02:40,720 --> 00:02:44,960
is with the acronym DAO,
or Data Access Object.

45
00:02:46,600 --> 00:02:49,990
This is a design pattern that's used
to abstract a way how you retrieve and

46
00:02:49,990 --> 00:02:50,980
store data.

47
00:02:50,980 --> 00:02:52,420
Check the teacher's notes for
more on this.

48
00:02:52,420 --> 00:02:55,140
So what we wanna do is in our new model,
here,

49
00:02:55,140 --> 00:03:00,120
we wanna make a new Java Class and
we're gonna change it to be an Interface.

50
00:03:01,210 --> 00:03:06,202
And what we're gonna make that

51
00:03:06,202 --> 00:03:11,196
called is the CourseIdeaDAO,

52
00:03:11,196 --> 00:03:14,661
Data Access Object.

53
00:03:14,661 --> 00:03:21,798
So all we really need for
this is a way to add new ideas.

54
00:03:21,798 --> 00:03:28,530
So we wanna make something called add and
it will take a CourseIdea,

55
00:03:28,530 --> 00:03:33,310
called an idea, and then we also
need to have a way to find them.

56
00:03:33,310 --> 00:03:34,180
So let's do that.

57
00:03:34,180 --> 00:03:40,025
Let's make a list of CourseIdeas

58
00:03:40,025 --> 00:03:43,890
and it's returned from a method
that's called findAll.

59
00:03:43,890 --> 00:03:45,880
Now note, because this is the interface,

60
00:03:45,880 --> 00:03:47,950
we aren't writing any
of the implementation.

61
00:03:47,950 --> 00:03:51,790
We're gonna do that now, so
let's add our silly implementation.

62
00:03:53,030 --> 00:03:56,050
So let's make a new class
in this model here.

63
00:03:57,170 --> 00:04:04,950
Make a new Java Class and we're going
to call it SimpleCourseIdeaDAO.

64
00:04:04,950 --> 00:04:09,390
Now, i'm calling it simple just to make
sure that we remember that this is

65
00:04:09,390 --> 00:04:12,450
a simple way of doing things,
this is not how we should actually do it.

66
00:04:12,450 --> 00:04:14,052
So let's do this.

67
00:04:14,052 --> 00:04:18,351
And what we want it to do
is wanna implement that

68
00:04:18,351 --> 00:04:21,770
Data Access Object interface.

69
00:04:21,770 --> 00:04:24,198
So that's the CourseIdeaDAO.

70
00:04:24,198 --> 00:04:25,884
Right away,
it's gonna start complaining, and

71
00:04:25,884 --> 00:04:28,300
it's gonna say that we need to
implement the methods, so let's do it.

72
00:04:29,480 --> 00:04:30,864
We'll implement both of these guys.

73
00:04:35,990 --> 00:04:41,286
Then, we're gonna need to have a private
list of ideas that will maintain,

74
00:04:41,286 --> 00:04:45,700
cuz we're gonna do this all
using normal data structures.

75
00:04:45,700 --> 00:04:48,020
We're not gonna be using a database.

76
00:04:48,020 --> 00:04:52,161
So we'll put here, we'll put private

77
00:04:52,161 --> 00:04:57,940
List<CourseIdea> and
we'll call those ideas.

78
00:05:00,510 --> 00:05:05,789
And on the constructor, [BLANK AUDIO] we

79
00:05:05,789 --> 00:05:11,787
will automatically just
create a new ArrayList.

80
00:05:11,787 --> 00:05:19,510
[INAUDIBLE] So
we'll say ideas = new ArrayList.

81
00:05:20,730 --> 00:05:21,230
Awesome.

82
00:05:22,660 --> 00:05:25,385
And it's using the diamond method.

83
00:05:25,385 --> 00:05:28,201
So now we just kinda do
what we would think.

84
00:05:28,201 --> 00:05:35,070
So if somebody calls add,
we wanna add our idea to our list.

85
00:05:36,920 --> 00:05:42,660
And then, just in case somebody tries
to get cheeky and does a findAll and

86
00:05:42,660 --> 00:05:47,770
appends the list, let's go ahead and
make sure that we make a copy of the list.

87
00:05:47,770 --> 00:05:49,990
So we're gonna say new ArrayList.

88
00:05:51,830 --> 00:05:56,190
And remember, collections can take another
collection and it makes a new one from it.

89
00:05:56,190 --> 00:05:59,730
So this is not actually
a reference to the list.

90
00:05:59,730 --> 00:06:03,890
It is a brand new list,
so you can't append this.

91
00:06:03,890 --> 00:06:08,565
You can't do findAll and then do your
own appending to it, make sense?

92
00:06:08,565 --> 00:06:13,100
And now for
the part that's pretty crazy/cool, ready?

93
00:06:13,100 --> 00:06:16,170
So we're gonna flip back to the app Main.

94
00:06:17,740 --> 00:06:21,800
And in here, remember we're
inside of a main method here.

95
00:06:21,800 --> 00:06:26,760
So let's go ahead and
make our model appear.

96
00:06:26,760 --> 00:06:34,300
So we're gonna say CourseIdeaDAO,
and we're gonna call that dao.

97
00:06:34,300 --> 00:06:40,410
So remember,
this CourseIdeaDAO is our Interface.

98
00:06:40,410 --> 00:06:42,290
And this is our implementation.

99
00:06:42,290 --> 00:06:44,500
So we're gonna implement
the SimpleCourseIdeaDAO.

100
00:06:44,500 --> 00:06:48,820
Now, later if we wanted to, we would
switch that out with the database one.

101
00:06:48,820 --> 00:06:54,870
So any one of these route methods
can now close over this DAO.

102
00:06:54,870 --> 00:06:56,220
Does that make sense?

103
00:06:56,220 --> 00:07:00,870
Now, I want to remind you this
should only be used for prototyping.

104
00:07:00,870 --> 00:07:02,350
Do not do this at home.

105
00:07:02,350 --> 00:07:08,170
This SimpleCourseIdeaDAO will
not survive a server restart.

106
00:07:08,170 --> 00:07:10,200
We'll talk about more of it here in a bit.

107
00:07:10,200 --> 00:07:14,250
But remember it's called simple,
don't do it at home.

108
00:07:14,250 --> 00:07:18,440
Please, please, please remember
that this is just a prototype.

109
00:07:18,440 --> 00:07:20,248
Do not run this live.

110
00:07:20,248 --> 00:07:24,670
That simple CourseIdea,
data access object, is goofy and

111
00:07:24,670 --> 00:07:26,520
won't survive a server restart.

112
00:07:26,520 --> 00:07:30,310
You really wanna persist or
save this data for later use.

113
00:07:30,310 --> 00:07:32,960
And our implementation is
really cutting corners.

114
00:07:32,960 --> 00:07:34,930
So after we use this a bit, you will for

115
00:07:34,930 --> 00:07:37,560
sure want to implement a data
based implementation, or

116
00:07:37,560 --> 00:07:42,500
even a file based implementation, just so
you don't need to keep re-adding things.

117
00:07:42,500 --> 00:07:44,190
That said though, let's go ahead and

118
00:07:44,190 --> 00:07:46,300
add the ability to add,
right after this break,