On this, day 10: we're going to talk about an ancient concept: frames.
If you're old enough on the Internet, like me, you might remember iframes.
They were these weird things where you could separate your site into different pieces.
And when you clicked a link inside a frame, the navigation stayed inside that frame.
It was like having separate web pages that you cobbled together into one.
The second part of Turbo is Turbo Frames...
which is a not weird, modern way to break your page down into parts...
kinda similar to iframes.
See this left sidebar?
When we click a planet, it takes us to the show page for that planet.
Cool. But not cool enough!
Instead, when I click a planet, I want that content to load right inside
of this sidebar without changing pages.
To do that, find the sidebar: it's over in templates/main/homepage.html.twig...
up near the top.
This partial renders that planet list.
To make this a frame, find the element that surrounds it and change it to <turbo-frame>.
And the one rule of frames is that each needs to have an id attribute.
It should be something unique that describes what it holds.
How about planet-info: Ok: what does that do?
At first, nothing.
A <turbo-frame> is just an HTML element like a div, and so it renders normally.
Though, for styling purpose, turbo-frame is an inline element by default.
However, when we click a link...
it's busted!
It says "Content missing".
And in the console: The response did not contain the expected <turbo-frame id="planet-info">.
When we click this link, it makes an Ajax request to the show page...
like it normally would with Turbo.
But because the link is inside a <turbo-frame>, it grabs the HTML and looks
for a matching <turbo-frame> with id="planet-info".
If it finds that, it grabs the content inside and puts just
that in the <turbo-frame> over here.
This means that each link inside a <turbo-frame> - whatever page it goes to -
that page must have a matching <turbo-frame>.
Copy this <turbo-frame id="planet-info> and then open planet/show.html.twig.
Put this around the content that we want to load into the sidebar.
I don't really want the h1...
so put it around this table.
Add the closing </turbo-frame> at the bottom: Refresh!
And click.
How cool is that?
It makes an AJAX request to this page, grabs just the <turbo-frame> content and puts it here.
You know what else would be great?
A "back" link!
To add that, still inside the <turbo-frame>,
add a <div class="mt-2"> then an a, href set to {{ path() }}.
Link to the homepage: Try it!
We don't even need to refresh.
Behold! A back link!
Whoops, let's make that more of an arrow.
When we click it...
it goes back!
That made an AJAX request to the homepage and looked
for a matching <turbo-frame id="planet-info">.
And guess what that holds?
This list of planets.
We're on a roll!
Before we finish today, add one more link: an edit link.
The route is app_planet_edit...
with id set to planet.id: Cool!
this time, if we click a planet...
then edit...
it doesn't work!
And I bet you can guess why.
It made an AJAX request to the edit page....
but there is no matching <turbo-frame> on that page.
And so, we get this error.
But... I don't want to add a <turbo-frame> to the edit page.
The form wouldn't fit into the sidebar anyway.
Nope, when I click this link, I want it to result in a "full page" Turbo navigation.
As soon as you add a <turbo-frame>, you need to keep track of the links that you have inside
of it and either make sure that each goes to a page that has a matching <turbo-frame>....
or that you target the link or form to do a full visit.
How do you do that?
Find the link, and add data-turbo-frame - that's a typo Ryan - set to _top:
Now, without refreshing, hit edit.
It still breaks.
I did the wrong thing.
It's data-turbo-frame="_top".
There we go.
Now hit edit.
Full page navigation!
It's still Ajax-powered, but the whole page changes.
The other way to target links or forms to the full page is on the <turbo-frame> itself.
You might say: Hey!
I want all links in this <turbo-frame> to be full page navigation by default.
To do that, set target to _top.
Then, if you have a specific link that you want to load in this frame,
add data-turbo-frame equals and then the id: planet-info.
Both approaches are fine: your call.
But adding target="_top" to each frame is a bit safer.
So this is working super well!
Except for the fact that if the user does ever get
to the planet show page, we have an extra set of links.
We really only want to show those when we're inside the <turbo-frame>.
How can we do that?
When Turbo sends an Ajax request for a <turbo-frame>, it does add a request header
that tells your app that this is a Turbo Frame request.
You can use that inside Symfony to conditionally do different things...
like conditionally render these links.
We are going to do that one time later in the tutorial.
However, I try to minimize this: it adds complexity.
Another option is to hide extra stuff with CSS!
For example, we could add a class onto the sidebar...
then only show these links if we're inside that class.
However, Tailwind doesn't really work like that.
In Tailwind, you can't change styling conditionally based on your parent.
At least not out-of-the-box.
But we can do this with a trick called a variant.
The first thing to notice is that a <turbo-frame>, by default, looks like this:
exactly like we have in our template.
But as soon as we click a link, it has a src attribute.
We can take advantage of that by adding a way inside of Tailwind
to style elements conditionally based on whether they are inside
of a <turbo-frame> that has a src attribute.
Because, it will have a src over here...
but won't have a src inside of this <turbo-frame>...
because it never navigates.
In fact, it would be a good idea to add a target="_top' to this frame,
since we don't need fancy frame navigation on this page.
Anyway, Tailwind variants are a bit more advanced, but simple enough.
Import this plugin module, then go down to plugins.
I'll paste in some code: This adds a variant called turbo-frame:
you'll see how we use that in a second.
It basically applies to an element that's inside a <turbo-frame> that has a src attribute.
Because we called this turbo-frame, copy that.
Now, in show.html.twig, add a hidden class to hide this div by default.
When we refresh, it's gone.
But then, if we match our turbo-frame variant, change to display block: Check it out.
When we refresh, those links are still hidden.
But over here...
we've got them!
Because we're inside a turbo-frame with a src attribute, our variant activates
and the display block takes over.
Turbo Frames do add some complexity, but we've only started
to scratch the surface on what they make possible.
Tomorrow, when I hover over each planet, I want to add a cool popover with more planet info.
To make that happen, we're going to install another third-party Stimulus controller.