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Displaying Categories

5:50 with Alena Holligan

In this video we’ll modify our function to show either the entire catalog or a specific category.

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To display only the category items, we're going to create a function to return the keys of items in that category. This will work much the same way as array_rand worked by returning and array of 4 random keys.

Step 1: Create the Function

The function needs to accept the catalog of data, and the category to use. It will then return an array of keys.

inc/functions.php

function array_category($catalog,$category) {
    $output = array();
    return $output;
}

Step 2: Check the Catalog for the Category

Now we need to loop through the items and compare the item category to the passed in category. We need the ID since we're going to return an array of ID's. If we DO NOT want case to matter when comparing these categories, we can use the strtolower() function.

inc/functions.php

    foreach ($catalog as $id => $item) {
        if (strtolower($category) == strtolower($item["category"])) {
            $output[] = $id;            
        }
    }

Step 3: Call the Function and Display the Items

This is going to work in the same way as our utilization of array_rand. We'll pass the $catalog data, and the $selection which represents our category. Then we loop through the returned array and display the item html.

catalog.php

$categories = array_category($catalog,$section);
foreach ($categories as $id) {
    echo get_item_html($id,$catalog[$id]);
}

Step 4: Show Full Catalog

To the top of the array_category function, we'll add an early return if the category passed in is "null", which means we are on the full catalog page. This will return all array_keys() in the catalog without having to perform any other tasks.

inc/functions.php

    if ($category === null) {
        return array_keys($catalog);
    }

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In the last video we used the built-in PHP function, array_rand, 0:00

to pull four random keys to use for our suggestions, displayed on the homepage. 0:04

For each of our categories, books, movies, and 0:09

music, we want to display just the items in that corresponding category. 0:12

To do this, 0:17

we'll create our own function that works much like the array_rand function. 0:18

We'll pass in two parameters and return an array of keys. 0:22

While currently, we only want to pull the category keys for 0:27

the catalog page, we may decide to use that for something else in the future. 0:30

Let's go ahead and 0:34

add that to our functions.php file in our includes directory. 0:35

Then we can simply include the functions file 0:39

if we want to use that function later. 0:41

Let's get coding. 0:43

Let's go back into functions.php. 0:45

We're going to add a second function called array_category. 0:48

For the parameters, we need the catalog array, And the category we wish to return. 0:56

We want to return an array. 1:08

So let's start by creating an empty array variable named output. 1:10

And we'll return output. 1:19

We need to loop through our catalog array, so once again we create a foreach loop. 1:23

foreach ($catalog as 1:27

$id => $item). 1:32

For each item, 1:37

we need to check if the category is the one that matches our category parameter. 1:37

If ($category ==, because we're comparing, 1:44

$item["category"]). 1:51

If you look at the data.php file, 1:59

you'll see that the values for the category are capitalized. 2:02

But we don't really need this to be case sensitive. 2:07

So we're going to use another built-in function and 2:09

convert both of these string values to lowercase. 2:12

The function is strtolower. 2:18

We simply pass the string value we want to convert, and 2:23

it returns the string converted to lowercase. 2:26

We add this to both our variables, and 2:36

now the capitalization of the category we pass in won't matter. 2:38

And how we've stored our variable won't matter. 2:43

We are looking only at the letters themselves. 2:47

If the category we passed in, matches the category of the current 2:50

item we are looping through, we need to add the id to the output array. 2:53

$output[] = $id;. 3:00

Our function is ready, we just need to call it from our catalog page. 3:07

Let's go into our index.php file, and 3:12

copy our call to our function, as well as our foreach loop. 3:15

Then we'll go into catalog and replace our foreach loop. 3:21

Now let's change these values a little. 3:26

Instead of random, we're going to be calling our category ids. 3:28

So let's call this $categories. 3:33

Next, we want to call our new function array_category. 3:41

We'll still pass the catalog variable but for the second parameter, 3:46

we need to pass the category. 3:50

At the top of this page, we already set the section variable. 3:52

Here, here, here, or here. 3:58

So let's use that. 4:05

Now when we preview our site and click on books, we see just the books. 4:09

When we click on movies, we see just our movie items. 4:16

And when we click on music, we see just our music items. 4:21

That looks great, but what happens when we wanna try to view the full catalog? 4:26

We don't see anything at all. 4:33

That's not what we want. 4:35

What we want is it to show all the items in our catalog on the full catalog page. 4:37

Let's take a look at our code. 4:42

On the catalog page, we're passing the category of books, movies, or music. 4:44

If we haven't chosen one of these, 4:49

we're passing the default of section which is null. 4:50

So we need to update our function to return all keys 4:54

if null is passed as the category. 4:57

In functions.php, let's modify our function. 5:00

At the top of the function, let's do a simple check. 5:05

If ($category == null) 5:09

we're going to return 5:15

array_keys($catalog). 5:19

You guessed it, it returns an array of just the keys. 5:25

Now when we go back to our browser and refresh the page, 5:29

we see all of our items on our full catalog page. 5:34

Our site is finally starting to look like a real library. 5:38

You're doing great. 5:41

You've learned a lot about arrays and functions. 5:42

There's just one more thing I think would be really helpful before moving on, 5:45

sorting. 5:49

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