Heads up! To view this whole video, sign in with your Courses account or enroll in your free 7-day trial. Sign In Enroll
Preview
Start a free Courses trial
to watch this video
Our Courses wouldn't be complete without Steps for students to follow.
IntegerField is a field that holds integers, or whole numbers.
An inline is a smaller form inside of a larger form. The smaller form represents a related record in the database.
StackedInline is an inline where each field takes up the full width of the form. Fields are stacked.
TabularInline is an inline where each field is part of a single row for the form.
More docs on inlines.
We have courses, but
each curse should have steps to it.
0:00
Maybe it will be videos, or
maybe it'll be text based steps, or
0:03
images, whatever method
you want to teach with.
0:06
Since I don't know what your
step of choice will be and
0:08
we're not gonna deal with video or
image uploads.
0:11
We'll just call them steps.
0:13
Anyway, let's get to it.
0:15
So since steps are a logical part of our
courses, we'll keep them in the same app.
0:16
So let's close some of
this stuff up again.
0:22
It gets a little unwieldy at times.
0:25
So inside courses, inside models.py,
we're gonna add our new model.
0:29
And we'll say class Step(models.Model).
0:39
So what goes into a step?
0:44
Well I think a title deserves to be there.
0:45
And this will again be a char field of,
0:49
255 characters or less.
0:54
I think we would have a description
just like our course would be.
0:58
So so far a step and a course
are the same thing just the created app.
1:04
I think we would have an order field,
1:09
so that we could specify what
order different fields come in.
1:11
And we'll set the default on this as zero,
and then let's do a course,
1:17
and this will be a foreign key,
and this will link back to course.
1:23
And since we know we're going
to print these out eventually,
1:32
let's do return self.typo.
1:35
Okay, so there's a lot here, the first two
items should be pretty familiar from our
1:37
course model, they're exactly the same.
1:42
The last two items though are new,
and I briefly went over them but
1:44
let's talk about them a bit more.
1:48
Order lets us control the order of steps.
1:50
Maybe we forget to create a step and
we have to create it later.
1:53
This way, we can add a new one, and we
can set where it should be in the order.
1:56
Setting it to zero makes it so
2:00
we can set other numbers to control
the ordering of steps later.
2:01
There are other solutions to this.
2:04
you could have them auto-increment.
2:06
You could set them at a negative, like,
there's different ways to do this.
2:07
Zero is a pretty safe default.
2:12
That we ordered automatically by their ID,
and
2:14
then we'll handle
the other ordering later.
2:18
And then,
the course attribute is a foreign key.
2:20
And a foreign key is a record or a column
that points to a record in another table.
2:23
Can be on the same table, but
for now it's in another table.
2:30
So, what we're doing is we're saying,
hey here's this step.
2:32
And maybe this is a step ID of three and
it belongs to the course with
2:36
an ID of one, so it belongs to that course
over there and points to that course.
2:42
This way, a single course
can have multiple steps, but
2:48
each step only has one course.
2:53
This is what is known as a one
to many relationship, or
2:56
we're looking at it from the step side,
a many to one.
3:00
Many steps belong to one course.
3:03
And then of course we have
our Dundar STR method,
3:06
which will print out
the title of the step.
3:09
You might want to print out the order but
3:10
I'll let you put that
in there if you want.
3:12
So now that we've made our our model.
3:14
Got ahead of myself.
3:17
Now that we've made our model, we,
of course, have to create a new migration.
3:18
You'll do this dance a lot.
3:22
You'll make a model,
then you'll make a migration,
3:25
and then you'll apply the migration.
3:28
It might seem monotonous and
3:30
time consuming, but it's good to know
exactly what's going on behind the scenes.
3:32
So, let's do this.
3:35
Python manage.py,
make migrations for courses.
3:36
Hey, we had to make one, cool.
3:42
Python manage.py,
3:44
migrate courses.
3:49
Done.
Applies all my migrations.
3:53
Okay.
3:54
So we've made our model.
3:55
We can play with it in
the shell if we want to.
3:56
But, I think it's easier just
to stick it in the admin and
3:59
then go mess with it in the admin.
4:01
And I bet you agree with me.
4:03
So let's run the server again.
4:05
And then shrink our terminal down.
4:08
And let's go look at admin.py.
4:12
And let's import Step and let's copy and
paste this line and change Course to Step.
4:15
So we've imported it, we've registered it,
things are cool right?
4:22
Let's go back to our admin and
check it out.
4:26
/admin, there's our steps,
there's our courses.
4:27
Okay, so let's go add a step.
4:35
So, we'll add a step, give it a title, and
we'll say What's the deal with strings?
4:37
Strings are more than
just a bunch of letters.
4:46
Find out why!
4:52
Okay, and the courses belongs to,
this is course of Pythons basics step.
4:56
So let's go ahead and save that.
5:01
Cool, now this isn't terrible but
5:03
we if we had a lot of courses
this might get really difficult.
5:05
That drop down, that can take a while
to read through and find stuff.
5:08
Probably a better way, and you know I
wouldn't ask that unless it was true.
5:13
Django lets us create smaller
forms that represent another model
5:17
inside the admin form for a model.
5:21
So we can edit and create steps for
our courses while we're editing and
5:24
creating a particular course.
5:27
We need to create two new classes for
this to work though.
5:29
So let's hop back over to our editor.
5:32
I get to do all of them
right here inside admin.
5:35
So now first we need to make the class for
5:38
our smaller form and
that's known as an inline.
5:40
So we're gonna say class
StepInline(admin.StackedInline).
5:43
Now there are two types of inlines.
5:50
There are stacked inlines and
tabular inlines.
5:52
We're gonna use the stack version, but
feel free to switch over to tabular and
5:55
try that out.
5:59
And we said our model is equal to step,
now that's it.
6:01
On it's own, this doesn't do anything,
but this creates the inline.
6:06
So now We have to make our next thing,
which is our course admin.
6:11
This is the admin for
handling our courses.
6:16
This let's us specify
custom special things.
6:20
So this is (admin.ModelAdmin) and
we're gonna set inlines = [StepInline,].
6:23
All right, now this is the one
thing that's a little bit weird.
6:32
When we made this StepInline,
we set model = Step.
6:35
We didn't set a model on course admin,
we do there here.
6:39
So we register course, and then we
register it with course admin, okay, and
6:42
if we want we can delete this, but
let's leave it alone for right now.
6:47
So let's come over here and look at
this again, let's go back to courses.
6:50
Courses, and let's look at Python
basics because we know it has a step.
6:54
Python basics, and look, here's our step.
6:59
What's the deal with strings?
7:01
Strings are more than just blah blah blah,
there's the order.
7:02
Here's where we can add a second one,
and a third one, and a fourth one, and
7:04
if we need to add more we
can click add another step.
7:09
So that's pretty awesome,
we can edit, delete, and
7:11
we can add new steps
right here in the admin.
7:13
There's a lot more that we can do with
inlines but this is enough for now.
7:17
I've linked to more documentation on
them in the teachers notes though, so
7:20
feel free to explore them
some more on your own
7:23
You need to sign up for Treehouse in order to download course files.
Sign up