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Since our Courses have Steps, let's add a view so we can see the steps for each course.
{% for step in course.step_set.all %} Notice that we don't use the () on all(). You don't call functions in Django's template tags, the template engine will handle that for you.
Also, step_set is automatically generated from the foreign key. Handy!
Model.get(attribute=value) lets you get a single Model instance by a given attribute's value.
Here is more info on prefetch_related and select_related. Don't bother too much with these until you're comfortable with Django's ORM.
Let's take a look at what
all we've done so far.
0:00
We have a project with an app, we have
a global project wide view, our homepage,
0:01
that renders a template.
0:06
That template also uses
a master layout template.
0:07
In our app we have two models and
two migrations.
0:11
We have our models registered
with Django's admin and
0:14
we have a view to see all of
the courses that we've created.
0:17
We've come a long way.
0:19
Great job.
0:21
Now let's go see about showing
the details of a single course.
0:22
So now we have two models and our admin is
set up to edit both of them pretty nicely.
0:26
So let's see about adding a view for
looking at a single course as a student.
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Let's get over here and
let's look at views.
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We have a way to view all of the courses.
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We get all the course names, right?
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It'd be really cool.
0:45
Let's open this up,
we're going to get another.
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All right, so we have our admin,
we have our view, we have our editor.
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A lot of tabs for
editing Django sometimes.
0:58
So, anyway, it'd be nice if we could just
click on, like, a course name, like, Boop!
1:00
Click on Python Basics, and go see all
the steps that are in that course.
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Normally we call this kind of view,
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when where you're drilling into
just a single item, a detail view.
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Because you're viewing
the details of a particular item.
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So we've got views.pi open, and
let's create this new view.
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We don't have to import anything.
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Because we've already got the render.
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We've already have our course model.
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We've already got that stuff.
1:38
Okay.
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We do need to catch the Primary Key
which is the ID field by default though.
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And, I know, we didn't define one.
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You remember talking
about that a while ago.
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Django automatically creates one for us.
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So we're cool.
1:51
We're good on that.
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Django saved us time.
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Thanks a lot Django.
1:54
So let's say course_detail, and
it of course has to take the request.
1:55
And then we'll say that it's
going to take a PK as well.
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Now this tells Python that we're going
to have two arguments to our view.
2:03
Django's going to automatically supply the
request when it calls the view function,
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and we will provide
the PK through our URL.
2:12
But we'll worry about that in a minute,
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the rest of our view is
pretty straightforward.
2:18
We need to get the course
with the given PK and
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then render the template,
so let's do that.
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Course equals course.objects.get,
where PK is equal to PK and
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then we're going to return
render the request object.
2:30
Courses slash course detail,
that HTML Course is going to equal course.
2:36
Okay.
2:43
Now we didn't define
a PK attribute either.
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So where did PK come from?
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Well, Django knows what
field is our primary
2:49
key which is what PK stands for,
Primary Key.
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By default, it's the ID.
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So, Django's like, oh, cool.
3:00
You want the primary key, you want the ID?
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Great, here you go.
3:03
Let's just go to it.
3:04
So we'll deal with what happens
if the course doesn't exist,
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a little bit later on.
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For now, though, let's just pretend that
nobody's ever going to type in a bad URL.
3:10
[LAUGH] And that reminds me,
we need a URL for this.
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So let's go check out our URLs.
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So we need to add a new line for
the next URL.
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And this URL is going to be really,
really similar.
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So we're going to do r and a quote and
then we're going to catch a PK,
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with a cap P there, and
then we're going to do a slash d.
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And there's going to be one or more of
those, and that's going to end the line.
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Now it's going to go to
views.course_detail and that's it.
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So what does this do?
3:50
This is a named group right here, and
we're going to call this group PK,
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that's the name of the group, is PK.
3:55
And it's going to be one or
more digits that come in the URL.
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That's going to go to course detail.
4:03
All right.
4:05
But, notice that we left off the chevron.
4:07
That's because our other URLs,
where are they, right here.
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We have this chevron here.
4:15
So the string starts with courses.
4:16
It can't start with the vk.
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Just a little bit of logic there, I guess.
4:20
All right, [LAUGH] so
last piece, we need a template.
4:23
So let's get our template.
4:25
So inside of our templates directory,
inside of our courses directory,
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we're going to create new file and we're
going to call it course detail.html and
4:30
inside course detail.html
we want to extend
4:36
our layout.html.
4:41
And then we want to be
able to set some stuff.
4:46
So let's set block title is equal to
whatever course we're looking at.
4:47
That course is title.
4:53
All right, and
then we're going to have block content.
4:58
So inside block content,
5:04
we're going to do any little bit of extra
HTML just to make our designers happy.
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So, we're going to have an article tag,
we're going to have an H2 tag,
5:12
with the course title.
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And, then let's do the course description.
5:22
And then,
5:26
we should probably also print out
the name for each step in our course.
5:30
Now we can do that by
looping through a new.
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Let's add a couple of things here first.
5:38
So we're going to do a section so
5:40
we can loop through
a special new attribute.
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That's called Stepset, and
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Stepset is a query set.
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So it's a bunch of records.
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And, since it's a query set,
we can query against it.
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So we're going to use
all to get all of them.
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And notice we don't include
the parenthesis when we're inside of
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Django's templates.
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So inside here we have
each thing called step.
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And we're going to print out something.
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So let's do step.title and
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then let's do step.description.
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So, we have our article tag.
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We have an H2, we have a description.
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We have our section tag.
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Inside here, we have an H3 and
a description.
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We end our section, we end our article.
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Pretty simple HTML, yeah?
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So let's see how it renders.
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So, we can't get to it from here.
6:44
But let's go.
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We know that Python Basics is number one.
6:49
And we forgot to close something.
6:52
We did.
This should be endfor not endblock.
6:55
Endfor.
6:59
Refresh.
7:02
There we go.
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Python Basics is the title of our course.
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Learn the basics of Python.
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And then What's the deal with
strings is one of the steps, and
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there's the description of that step.
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Not too bad.
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Django's ORM really helped us out
there with step set attribute.
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Sometimes though that ends up being a less
than optimal addition to your queries.
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I'll link to a couple of really handy
RM functions named select related and
7:22
prefectrulated.
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They're outside of the scope of this
course, but they can come in really handy.
7:27
We'll definitely cover them in a later
course, but check them out right now.
7:30
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