With our model and data repository in place, let's move on to the controller.

We'll need a controller for categories that can capture requests to a URI for

all the categories and a URI for a single category.

So, here's your next task.

Create a Category Controller with one method [SOUND] that captures requests to

/categories and returns a String.

This method should fetch the entire list of category objects from

an auto-wired category repository and add it to a ModelMap.

[SOUND] Then, the method should return the string categories to associate it

with the provided Thymeleaf Template.

Are you ready for this?

Okay.

Go ahead, have at it.

But wait, remember to use the GIF controller as an example to follow.

Ready, set, code.

>> All right, what you're looking at here is my category controller class,

which I put in the controller package with the other controller.

You can see that I've annotated the class with Controller and included an Autowired

category repository that I can use in the controller method down here.

As for this method, I've annotated it with request mapping to capture

any requests for the category list page, which is /categories.

Here is my modelMap parameter, and inside is the the call to the repository's

getALLCategories method that we wrote together earlier.

I added the list that was returned by this method to the modelMap using

modelmap.put here.

And here I've returned the name of the time leave template, or categories.

This is will ensure that it's the categories.html template that will be

rendered when this page is requested.

The last piece of this controller, we'll do together.

We'll need another method that will capture requests to an individual

category.

To start that, I'll request a mapping to a single category page,

category/, and here we're going to use an integer id.

The name won't work well as a URI placeholder

here because names could have spaces in them.

So instead, I'll use the integer id as a placeholder.

Then we'll start typing the method public String category.

And the first parameter I'm going to list is our @PathVariable.

That will capture the value that's passed into

the id placeholder that's in our RequestMapping annotation.

So I will call it id.

And of course, we'll include an instance of a modelMap that'll

be passed in by the Spring framework.

>> Now, I know I'm going to return the single categories template,

which is given in category.html, so I'll type in that return value right now.

That's going to be return "category".

Now I know the category page in the browser should probably

contain the category name, as well as

all GIFs related to that category, >> So by the time we reach the return

statement we better have added to the model map, both a category object

associated with this ID as well as a list of GIFs associated with this category.

Let's tackle each of those now.

First, the category object.

You just wrote a findById method, so

we'll call that now and add the result to the model map.

I'll create the category object,

And use the categoryRepository field and call its findById method

passing it the integer id that came into our path variable.

Then I'll add the category object that was returned by the findById method to

the model, using modelMap.put.

The name I'll give it will be simply category, and I'll pass category.

Whatever value was stored in there as a result of this return value,

I will add to the ModelMap.

Now onto the next item.

For a list of the GIFs associated with this category, we'll need to use a GIF

repository to fetch all those GIFs within a certain category ID, like this.

I'll give myself a couple lines to separate this code.

And the first thing I'll do is define a list that'll

hold that list of GIFs that comes back from the GIF repository.

Make sure to import the GIF class there, since we haven't done that yet.

And I'll call the gifRepositories,

findByCategoryId method, passing it the id.

And finally, adding that list to the model map with modelMap.put.

I'll call that "gifs" in the map key, and pass it the object gifs.

But wait, there are two problems with this.

First, there is no GIF repository variable defined.

And second, there is no findByCategoryId method defined for

a GIF repository object.

The first one we can fix right here.

We'll simply add an Autowired gift repository to the object.

So I'll add that with the @Autowired annotation, add a GifRepository.

That fixes the first error, but

we still have this error with the missing findByCategoryId method.

This one will take a bit more work.

But it's still pretty quick.

We'll hop over to the GifRepository class, and add a findByCategoryId method.

So let's scroll down here and I'll just add it to the bottom.

That'll return a list.

FindByCategoryId, and let's have it accept a single end parameter.

So this method, given some int id, will essentially iterate over our

list up here looking for objects that have a given category id.

If they haven't given a category id,

I will include those in the list that I return.

So to start, we better initialize a brand new empty list.

I'll make it a list of GIFs and initialize it as a new ArrayList.

Make sure to import those classes, excellent.

Now, let's use a for each loop to iterate over the list of ALL_GIFS.

So for every Gif, I keep typing Fig, how about Gif?

For every Gif in ALL_GIFS Let's

check to see if the category id of the Gif object in this iteration of the loop is

equal to the id value that was passed in as a parameter.

So, if gif.getCategoryId ==,

I can use double equals here.

It's a primitive value.

I don't need to use dot equals.

Then what I want to do is add that to the list.

So, by the time we get through this loop, any Gif in the list that has the category

ID that was passed in as a parameter value,

will be added to the list name Gifs.

And once I get through my loop, what I'd like to do is return

whatever list has resulted by iterating over all gifs.

Now that we've coded this method, after we jumped back to the category controller

class, we should see that that error right there has been resolved,

since we created that method.

At this point, we should at least be able to see the category list page,

even if it hasn't been infused with live data.

Let's redeploy and check it out.

So if your boot run task is still running, go ahead and stop it.

And after a few moments,

you can rerun that bootRun task to reboot your server and redeploy your web app.

And it looks like I have a compiler error.

I see what happened here.

So this error right here says that I can't

leave this generic between these angle brackets here empty.

And why does it say that?

Well, it says that because in my build file, if I go to my build file,

build.gradle, I said I wanted my Java source code to

be compatible with Java five, that is version 1.5, and

I have to use source 7 or higher to enable the diamond operator.

That's the operator that allows us to leave that generic empty.

So, what I'm going to do is, well, I could do one of two things, I could remove

the source compatibility here, I could increase the source compatibility here, or

I could go back to this line right here, and actually add gif right there.

I'm simply actually going to delete the source compatibility.

Delete that.

We'll save it and now I'm going to rerun the bootRun task.

And there it looks like the compilation has succeeded.

And the web server's up and running.

My application is deployed.

Let's check it out.

So I'm going to go back to my main page.

There's the home page, we didn't touch it in this last task.

What we did touch, though, is the Categories page.

And there it is!

It's working!

We see that the template is actually displayed, though it has static HTML.

And from this, you can probably guess what your final task is going to be.