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Complex Data Types

6:21 with Alena Holligan

There are MANY different ways to handle switching out the data source. Since this course is on Environment Variables, I'm going to show you ONE way to use environment variables by storing a complex data type using JSON.

Teacher's Notes
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Video Transcript
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More Explanation

This video went quickly though a number of items you should already be familiar with. If you would like a refresher, please check the following resources.

File Handling with PHP - where we cover Reading JSON and Writing JSON
putenv() function - Sets the value of an environment variable. The environment variable will only exist for the duration of the current request. At the end of the request the environment is restored to its original state. This can be useful for testing.
PHP Arrays and Control Structures where we cover switch statements
Integrating PHP with Databases where we cover PDO

Code Example

// set environment variable
putenv('REPOSITORY={"type":"sqlite","source":"inc/quotes.db"}');

//read environment variable into an object
$repository = json_decode(getenv('REPOSITORY'));

switch ($repository->type) {
  case 'text':
    $file = file($repository->source);
    // grab a random array element
    $quote = $file[array_rand($file)];
    break;
  case 'sqlite':
    try {
      //if you are working in workspaces you will most likely need to start with 'sqlite:/www/'
      $db = new PDO("sqlite:" . $repository->source);
      $db->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
      $result = $db->query('SELECT quote FROM Quotes ORDER BY RANDOM() LIMIT 1');
      $quote = $result->fetchColumn();
      break;
    } catch (Exception $e) {
      echo "Error!: " . $e->getMessage();
    }
  default:
    $quote = 'It works on my machine.';
}

Optionally you can decode JSON data into an associative array if you prefer, by setting the second parameter of the json_decode function to true.

$repository = json_decode(getenv('REPOSITORY'), true);

switch ($repository['type']) {
...

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We're going to start on the index page. 0:00

There are many different ways to handle switching out the data source. 0:02

Since this course is on environment variables, I'm going to show you 0:06

one way to use environment variables by storing a complex data type. 0:10

Before I add anything to the .env file, let's play around on the homepage. 0:15

Right at the top of the file, we'll add a line to putenv. 0:19

And then within single quotes, we'll add a REPOSITORY, That equals the JSON's string. 0:25

"type": will equal "text" And 0:34

source will equal inc/quotes.txt. 0:40

Now let's just switch out what we have. 0:51

First, we're going to set a variable 0:55

$repository = to the json_decode(getenv('REPOSITORY')). 1:00

Now let's echo the type, echo $repository->type. 1:14

Now let's change out the source. 1:22

Repository, Source. 1:27

Let's go back to the browser and verify that everything is still working. 1:32

Looks good, we still have our random quote and we are also showing the type. 1:38

Let's go back and add a switch statement based on type. 1:43

Switch, This 1:50

is going to be based on our repository-->type. 1:56

For the current settings, we're going to use the text type. 2:03

So case 'text'. 2:06

Let's also set a default value. 2:19

So we want to add the break, and then a default. 2:21

We're going to set quote = It works on my machine. 2:28

And close that our sweet statement. 2:38

Let's do a quick check to verify that everything is still working. 2:40

Looks good. 2:46

Let's change the type to unknown. 2:47

Now we see the type of unknown and we also see our default value, 2:58

no matter how many times we refresh. 3:02

Now let's add a second SQLite source. 3:05

Case 'sqlite And 3:17

then we are going to wrap this in a try catch block. 3:22

Try, and we'll start with our connection. 3:26

We'll add a new PDO. 3:31

Sqlite:/www/" and our repository, 3:37

Source. 3:45

Then we also need to set our error modes. 3:48

Set attribute PDO::ATTR_ERRMODE, 3:52

and PDO::ERRMODE_EXCEPTION. 4:01

Now we can add our catch. 4:15

Exception into $e. 4:19

Now we are ready to select a random item from the database. 4:39

$result = $db->query(' 4:45

quote FROM Quotes ORDER BY 4:55

RANDOM() LIMIT 1'). 5:03

And then we're going to set quote, = the result. 5:11

And then we'll fetchColumn to fetch the single result. 5:21

And finally, add our break, but only if I try works. 5:27

If not, we still wanna get our default quote. 5:33

Before we test this out, let's change our repository variable. 5:36

We'll change it to sqlite and our quote is db. 5:51

Now, let's go back to the browser. 5:56

Back in the browser, we can see that our type is now sqlite, and 6:00

it's now pulling a random quote from the new database. 6:03

Before I clean this up, and move the repository to my .env file, 6:09

what happens if one of our environment variables isn't set? 6:13

Let's check out a few more details before we finish. 6:18

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