parse error: syntax error expecting catch (T_CATCH) - php

Question

I am new to PHP and I'm trying to learn PDO. I'm trying to build a page where I can post information (news and such) to a database and another page where I can view the things in the database.
I've read here that people say you shouldn't use the try catch operator to handle error messages. I understood this as you shouldn't use something like:
CreateNews.php
<?php
header("Content-Type: text/html; charset=utf-8");
// Create presets for connection
$dsn = "mysql:host=localhost;dbname=dbname;charset=utf8'";
$opt = array(
PDO::ATTR_EMULATE_PREPARES => false,
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES 'utf8'"
);
// Check if form is being posted
if ($_SERVER['REQUEST_METHOD'] == "POST") {
// Check if fields are empty
if (!$_POST['name'] || !$_POST['email'] || !$_POST['title'] || !$_POST['content'] || !$_POST['timestamp']) {
echo "<p>Please fill in all of the fields!</p>";
exit();
}
else {
try { // Connects to server and executes the transfer of data
$pdo = new PDO($dsn, 'root','', $opt);
$sth = $pdo->prepare("INSERT INTO news (name, email, title, content, timestamp)
VALUES (:name, :email, :title, :content, :timestamp)");
$sth->bindParam(':name', $_POST['name']);
$sth->bindParam(':email', $_POST['email']);
$sth->bindParam(':title', $_POST['title']);
$sth->bindParam(':content', $_POST['content']);
$sth->bindParam(':timestamp', $_POST['timestamp']);
$sth->execute();
}
catch (PDOException $e) {
echo $e->getMessage();
}
echo "<p>Data submitted successfully!</p><br />To create another post <a href" . $_SERVER['PHP_SELF'] . ">click here</a>";
}
}
// Close the connection
$pdo = null;
?>
So I removed the catch PDOException above and then got the error message:
Parse error: syntax error, unexpected 'echo' (T_ECHO), expecting catch (T_CATCH)
If I remove the echo I still get the "expecting catch T_CATCH error.
Have I misunderstood what people mean when they say that you shouldn't use try catch operators?
And if so how should I use it?
Please feel free to comment if you notice anything in the code that I've done wrong or unnecessarily. I'm new to all this and still trying to learn! :)
Thanks!

Answer 1

I've read here that people say you shouldn't use the try catch operator to handle error messages.
These people are quite right.
What to NOT use exceptions for
Exceptions should not be used for normal flow of applications.
Let's take a look at the inverse($x) function from the php manual, which returns 1/$x and throws an exception if you pass in 0 as $x since you cannot divide by 0.
Let's further assume that your variable comes from a posted form, so one could enter 0. In this case you should check with an if-clause for correct values like:
<?php
if (intval($_POST['value']) == 0) {
echo 'You cannot pass 0 into inverse(). Please enter another value.';
} else {
echo 'We computed the inverse: ' . inverse(intval($_POST['value']));
}
?>
You should not use try-catch constructs for this type of use. It is totally expectable in this situation that a user might enter a number the function cannot deal with. You should check inside your normal application flow for wrong values and deal with them.
What to use exceptions for
Let's assume now that the variable $x is filled by supercomplicated_function, which always returns a number and never returns 0. Since you are sure, that the variable will never ever equal 0, why should you check for this case?
Instead you can use try-catch here:
<?php
$x = supercomplicated_function();
try {
$y = inverse($x);
echo 'We computed the inverse: ' . $y;
} catch (Exception $e) {
echo 'Unexpected situation. Do not know how to go on. Aborting.';
die();
}
?>
Clues to look for
If you expect some specific error under normal conditions, you should check for them with an if statement.
If you do not, let exceptions handle the issue.
In your case, you normally do not expect an exception from a query execution. Possible error causes are server has gone away or deadlock. This errors are possible, but not under "normal" conditions. So you do not want to check for them with if statements (you even cannot check for a possible deadlock beforehand).
Therefore in your case you want to use exceptions. That's totally ok.