1
00:00:00,340 --> 00:00:04,580
Our models have five really useful methods
that we'll be using a lot.

2
00:00:04,580 --> 00:00:06,780
Create, adds a new record to the table.

3
00:00:06,780 --> 00:00:10,010
Select, let's us pick rows out of the
table to use.

4
00:00:10,010 --> 00:00:13,110
Save, will update an existing row in the
database.

5
00:00:13,110 --> 00:00:15,580
Get, will fetch a single record from the
database.

6
00:00:15,580 --> 00:00:19,200
And finally, delete_instance will delete a
row from a table.

7
00:00:19,200 --> 00:00:22,180
There are many other methods on Peewee
models but I leave them for

8
00:00:22,180 --> 00:00:25,390
you to read about in the docs linked in
the teacher's notes.

9
00:00:25,390 --> 00:00:28,620
Okay.
So let's setup some of the info that we

10
00:00:28,620 --> 00:00:31,180
want to have inserted into our database.

11
00:00:32,310 --> 00:00:37,390
Like I said, we're gonna use a dictionary
to hold on to all the data.

12
00:00:37,390 --> 00:00:38,090
And the reason for

13
00:00:38,090 --> 00:00:43,300
that is because a dictionary is easy to
look back to, it's easy to update.

14
00:00:43,300 --> 00:00:44,370
We can play around with it.

15
00:00:44,370 --> 00:00:48,080
We've all had a lot of experiences with
databases or dictionaries.

16
00:00:48,080 --> 00:00:50,310
So, not anything crazy.

17
00:00:50,310 --> 00:00:55,830
So, I'm actually gonna make a list for all
the students and

18
00:00:55,830 --> 00:00:57,860
then a dictionary per student.

19
00:00:57,860 --> 00:01:04,110
So, let's make a username and then I'm
gonna say,

20
00:01:04,110 --> 00:01:10,941
Kennethlove, and we'll say points and
4888.

21
00:01:10,941 --> 00:01:11,802
All right.

22
00:01:11,802 --> 00:01:14,622
And then username.

23
00:01:14,622 --> 00:01:17,702
Chalkers, points.

24
00:01:17,702 --> 00:01:22,463
[BLANK_AUDIO].

25
00:01:22,463 --> 00:01:23,823
Username.

26
00:01:23,823 --> 00:01:31,162
[BLANK_AUDIO]

27
00:01:31,162 --> 00:01:35,245
If you've explored the collections
library,

28
00:01:35,245 --> 00:01:41,290
then this is actually a really great place
to use something like named tuple.

29
00:01:44,390 --> 00:01:49,480
This is also something where we probably
could have done a dictionary where

30
00:01:50,710 --> 00:01:53,920
each key is the username, and the points
are their value.

31
00:01:55,130 --> 00:01:57,830
But this is a little bit more obvious of
how we're going to

32
00:01:57,830 --> 00:02:01,880
put things into the database in the end.

33
00:02:04,000 --> 00:02:06,430
And [INAUDIBLE].

34
00:02:06,430 --> 00:02:08,310
Dave has a lot of points.

35
00:02:09,330 --> 00:02:10,410
All right.

36
00:02:10,410 --> 00:02:15,400
So, here's our dictionary or our list of
dictionaries, rather.

37
00:02:15,400 --> 00:02:18,800
So you can see, we've got two keys for
every one of them, we've got username key

38
00:02:18,800 --> 00:02:22,200
and we've got a points key for each one of
them, and then they have a value that has

39
00:02:22,200 --> 00:02:24,870
their username or their points, depending
on which key it is.

40
00:02:26,250 --> 00:02:30,710
So, let's add a function that will go
through all of these,

41
00:02:31,960 --> 00:02:35,750
and add them to our database, and let's
call it add students.

42
00:02:39,440 --> 00:02:45,100
And what we wanna do in here is, we wanna
go through each student in students, and

43
00:02:45,100 --> 00:02:49,450
we wanna use our model, which is called
Student, and I'm gonna call create.

44
00:02:49,450 --> 00:02:56,465
And we're gonna say the user name is equal
to the student username.

45
00:02:57,910 --> 00:03:03,204
And the points is equal to the student
points.

46
00:03:03,204 --> 00:03:11,500
All right, so now let's come down here to
our if name block and

47
00:03:11,500 --> 00:03:17,062
let's add that in, so down here we wanna
call add students.

48
00:03:17,062 --> 00:03:19,080
'Kay.

49
00:03:19,080 --> 00:03:22,413
So, let's try running this.

50
00:03:22,413 --> 00:03:27,540
Python students.py.

51
00:03:27,540 --> 00:03:28,880
Okay, no problems.

52
00:03:28,880 --> 00:03:34,230
This is all great and wonderful until we
run it again.

53
00:03:35,730 --> 00:03:37,650
Look at this.
We've got all, we got tons and

54
00:03:37,650 --> 00:03:39,150
tons of these integrity errors.

55
00:03:39,150 --> 00:03:40,130
Now, why did we get those?

56
00:03:40,130 --> 00:03:45,247
We got those because, remember we made our
username unique.

57
00:03:46,500 --> 00:03:50,250
And what we're doing down here is a
create.

58
00:03:50,250 --> 00:03:53,451
We're saying, put in a new row for every
single one of these.

59
00:03:53,451 --> 00:03:57,460
So the first time through it puts in that
new row for Kenneth Love.

60
00:03:57,460 --> 00:03:59,780
And everything's cool, everything's
copacetic.

61
00:03:59,780 --> 00:04:02,880
The second time it comes through, it says
hey, put in a row for

62
00:04:02,880 --> 00:04:07,250
Kenneth Love, and the database says, no
wait, I can't, I already have

63
00:04:07,250 --> 00:04:12,180
a row where the username is Kenneth Love,
I can't do a new one, because it's unique.

64
00:04:12,180 --> 00:04:13,110
So let's change this, and

65
00:04:13,110 --> 00:04:18,760
the way that we're gonna change this, is
we're gonna do a tri-block.

66
00:04:18,760 --> 00:04:19,260
Oops.

67
00:04:23,070 --> 00:04:24,040
So we can indent that.

68
00:04:24,040 --> 00:04:30,030
So we're gonna try to insert the, the
student.

69
00:04:30,030 --> 00:04:33,270
And you notice that we're getting this
integrity error down here in our

70
00:04:34,410 --> 00:04:35,280
error messages.

71
00:04:35,280 --> 00:04:37,840
So we're gonna except IntegrityError.

72
00:04:39,200 --> 00:04:44,821
So if we get an integrity error, then
let's do student_record.

73
00:04:44,821 --> 00:04:53,590
Oops, student_record equals Student.get,
username equals student, username.

74
00:04:55,880 --> 00:05:01,530
Right, so we wanna get that student, it
must exist, so we wanna get that student.

75
00:05:01,530 --> 00:05:06,640
And then we want to do
student_record.points equals

76
00:05:06,640 --> 00:05:07,640
student points.

77
00:05:08,770 --> 00:05:14,090
So set their points to the new one, and
then student_record.save.

78
00:05:14,090 --> 00:05:16,840
So, get the student out of the database.

79
00:05:16,840 --> 00:05:19,560
Change the points to whatever the points
is now.

80
00:05:19,560 --> 00:05:21,570
If it's changed, it may not have changed.

81
00:05:21,570 --> 00:05:24,820
But just set it to whatever it is now, and
then save the record.

82
00:05:24,820 --> 00:05:26,100
Now we can make this smarter,

83
00:05:26,100 --> 00:05:31,130
as I just mentioned, by making it check to
see if the points is different.

84
00:05:31,130 --> 00:05:32,730
I'm gonna leave that up to you.

85
00:05:32,730 --> 00:05:35,970
But that would be a good thing to do.

86
00:05:37,250 --> 00:05:42,430
All right, so now, let's add another new
function.

87
00:05:42,430 --> 00:05:44,740
Actually, let's go ahead and test this one
first.

88
00:05:45,780 --> 00:05:46,470
Let's do Save.

89
00:05:46,470 --> 00:05:47,380
Let's come back down here.

90
00:05:47,380 --> 00:05:48,458
We should be able to run this again.

91
00:05:48,458 --> 00:05:52,610
No complaints, great.

92
00:05:52,610 --> 00:05:55,380
'Kay, so now let's make a new function
that is

93
00:05:55,380 --> 00:05:58,090
going to get our top performing student.

94
00:05:58,090 --> 00:06:02,550
I want the student that has the, the
highest number of points.

95
00:06:02,550 --> 00:06:06,118
So we'll call this top student and

96
00:06:06,118 --> 00:06:11,760
we'll say student equal student, our
modal, .select.

97
00:06:11,760 --> 00:06:15,300
So what that does is that gets all of the
students.

98
00:06:15,300 --> 00:06:18,390
We've got all of the student records that
are in the database, 'kay?

99
00:06:18,390 --> 00:06:21,220
We don't want all of them, we just want
the best one.

100
00:06:21,220 --> 00:06:25,650
So let's do an order by, so let's sort
them and

101
00:06:25,650 --> 00:06:31,660
we're gonna sort them by the points
attribute, right?

102
00:06:31,660 --> 00:06:34,260
We wanna sort by whoever has the most
points.

103
00:06:34,260 --> 00:06:37,390
And we wanted to do this in descending
order, so

104
00:06:37,390 --> 00:06:41,730
we want the biggest number first, the
smallest number last.

105
00:06:41,730 --> 00:06:44,750
Ascending would be the other way around
where we have the smallest number first

106
00:06:44,750 --> 00:06:45,970
and the biggest number last.

107
00:06:45,970 --> 00:06:48,040
So descending, it gets smaller.

108
00:06:48,040 --> 00:06:49,600
Ascending, it gets bigger.

109
00:06:51,820 --> 00:06:54,920
So let's add one more thing to this.

110
00:06:54,920 --> 00:06:58,960
What we can do is we can say .get on the
end of this.

111
00:06:58,960 --> 00:07:03,150
And that's going to only get us the first
record that comes back.

112
00:07:03,150 --> 00:07:04,700
So we've got all the students.

113
00:07:06,050 --> 00:07:08,410
Sort them all by their points so

114
00:07:08,410 --> 00:07:12,020
that the biggest number comes first, and
then get the first record.

115
00:07:12,020 --> 00:07:16,030
I know there's a lot there, but that's
what it is.

116
00:07:16,030 --> 00:07:16,550
Okay.

117
00:07:16,550 --> 00:07:21,331
So, let's return a student.username.

118
00:07:21,331 --> 00:07:21,872
Actually, you know what?

119
00:07:21,872 --> 00:07:24,211
Let's just return student.

120
00:07:24,211 --> 00:07:25,390
Okay?

121
00:07:25,390 --> 00:07:30,830
And so, what I wanna do is down here,
after I add the students,

122
00:07:30,830 --> 00:07:36,810
I want to print our top student right now
is.

123
00:07:38,650 --> 00:07:44,938
And then I'm gonna do a format here where
I call top_student.

124
00:07:44,938 --> 00:07:52,930
And so let's actually go here and do
0.username.

125
00:07:52,930 --> 00:07:56,530
Cuz zero is whatever comes back from this,
and

126
00:07:56,530 --> 00:08:00,053
we know that has a username attribute so
we're gonna print out 0.username.

127
00:08:01,482 --> 00:08:05,160
All right, so moment of truth, let's give
this a try.

128
00:08:09,740 --> 00:08:10,240
oh.

129
00:08:11,360 --> 00:08:13,610
I forgot a parenthesis.

130
00:08:13,610 --> 00:08:14,660
All right, now let's try it.

131
00:08:14,660 --> 00:08:18,300
Our top student right now is Dave
Mcfarland.

132
00:08:18,300 --> 00:08:19,240
Sweet.

133
00:08:19,240 --> 00:08:20,430
Dave's got a lot of points.

134
00:08:22,180 --> 00:08:23,100
Let's go change that.

135
00:08:23,100 --> 00:08:26,840
Dave's got a whole bunch of points, but I
wanna be the top student.

136
00:08:28,300 --> 00:08:32,525
So, whatever Dave has, plus 1.

137
00:08:33,780 --> 00:08:36,850
Okay, so now if I run this, it should come
back as me being the top student.

138
00:08:38,850 --> 00:08:39,980
Great, it did.

139
00:08:39,980 --> 00:08:41,720
Now why did it change to me?

140
00:08:41,720 --> 00:08:45,350
Just in case you didn't catch this part
yet, it's because of this.

141
00:08:45,350 --> 00:08:46,420
We had the integrity error,

142
00:08:46,420 --> 00:08:50,750
there's already a row for me, so now we
grab my student record,

143
00:08:50,750 --> 00:08:54,450
update my points to whatever's in the
dictionary, and we save it again.

144
00:08:54,450 --> 00:08:58,430
Then when we run top student, it's gonna
select my record.

145
00:08:58,430 --> 00:08:59,300
So that's pretty awesome.

146
00:08:59,300 --> 00:09:01,170
We're able to get our students from the
dictionary.

147
00:09:01,170 --> 00:09:02,780
Stick them into the database.

148
00:09:02,780 --> 00:09:06,220
Select them, order them, pick out just one
top one.

149
00:09:06,220 --> 00:09:10,450
And then we were even able to update and
change those records afterwards.

150
00:09:10,450 --> 00:09:15,400
This work, creating, reading, updating,
and deleting records is known as CRUD.

151
00:09:15,400 --> 00:09:19,000
It's the backbone of pretty much any
application that deals with a lot of data.

152
00:09:19,000 --> 00:09:21,460
I can see you're getting antsy to build
something real already.

153
00:09:21,460 --> 00:09:25,280
Well, that's great because our next step
is to start the real reason we're here.

154
00:09:25,280 --> 00:09:27,210
A command line diary application.

155
00:09:27,210 --> 00:09:28,350
We'll do that in the next stage.