Now that we have our CSS setup and

ready to go, let's see about making our data more dynamic using template filters.

Remember that a filter is applied to a variable that you

pass into your template from your view, and uses the pipe notation.

Let's look at some of the filters that Django includes for us.

Open up coursedetail.html.

So let's add a section at the top

that lists out all of the steps in this course in paragraph form.

So, these are the steps in this course,

c ourse.step_set.all.

Let's start our server and see what this looks like.

So we changed directories into our learning site, and then run the command,

python manage.py runserver on our favorite port.

Now we can use the eye to preview our page and

we'll go into courses and select Python Basics to be our test course.

And now we can see the sentence that we added.

But, this doesn't render very well, does it?

The new information that we added is appearing in these brackets, and

it's not very readable.

We can use a join filter to break up the items between these brackets

without having to go into a for loop or doing any other processing.

So let's try that.

Right here after all, we add the pipe character, and

then the word join because we're using the join filter.

And now we have to pass in the thing that we want to separate our items by.

And we do that by using a colon and then opening some quotation marks.

Whatever we want to use to separate these items will go between the quotation marks.

In this case since we're adding these items to the end of a sentence,

I want to separate each step with a comma and a space.

Now we close the quotation marks, save the template, and

we can refresh our page to see what this looks like.

Now this is much better.

But if we use the length filter, we can make this sentence even more useful.

Using the length filter gives you the number of items in a particular set.

So let's see how that works.

So instead of saying these are the steps we can say

there are a specific number of steps.

And we can get at that number by doing course.step_set.all

using the pipe character again and adding the length filter.

The way the length filter works is this,

even though we have this whole expression course.step_set.all

that uses our whole step set, we won't see any of the data in that set.

We won't see the titles that we see later on in the sentence for example.

Instead, the length filter just gives us the length of the set, or

in other words, the number of items in the set.

So if we save this template and reload our page, we should see a number, and we do.

There are two steps in this course.

This works fine, but we should really be using a built-in method called count.

The length filter causes a large database query to be run, so it saves our

database some trouble if we use count instead, because it's more efficient.

So let's make that change.

We can replace all type length with just count.

And whenever we refresh our page we see that nothing has changed,

everything is the same.

We've just made our website more efficient with this very simple change.

Now, the parenthesis s parenthesis that we have in the word steps isn't

very readable.

This is where another filter comes in.

We can use the pluralize filter to make the word step singular or

plural based on the number of steps in that set.

So let's try this out.

We just delete this entirely, and replace it with course.step_set.count and

then that pipe character and the word pluralize.

This one looks a little weird because you have to type the word step as singular and

then immediately follow it with the set you're referring to in

the pluralize filter.

But basically, you're telling Django to make this particular word, step, plural or

singular based on the number of steps in this set that you've attached to it.

Again, the contents of the set won't render and the number won't render.

The only thing you'll see is an S on the end of the word step or

not, depending on how many steps are in this course.

Let's refresh the page, and you can see what I mean.

And there you have it.

There are two steps plural in this course.

There are also some other template tag libraries that we can use in our projects.

Let's test one out in the next video.