How to check a called string within a php string is set? - php

Question

I'm looking to call multiple strings and concatenate them into a single string. I want to be able to check that all of the strings that are being called are set, WITHOUT having to isset(); every single string that is used.
What I'd ideally like to have:
<?php
$name = "John Smith";
$age = "106";
$favAnimal = "pig";
$email = "john#smith.com";
$sport = "tennis";
$userDescription = "My name is $name, I am $age years old, I like $sport.";
if(allStringsSet($userDescription)){
echo $userDescription; //Or do something else
}
?>
You will notice that I'm not calling all of the strings, as in my application not all of the strings will be used all of the time. Also my application will be choosing from about 50 strings and I need to be able to check any are set without a pile of isset();s everywhere.
I expect that the isset checking needs to happen before the $userDescription is declared. How can I check an unknown set of strings to see if they are set?

Answer 1

Use an object with custom getter and setter.
class CustomStrings()
{
protected $data;
public function __set($key, $value) {
$this->data[$key] = $value;
}
public function __get($key) {
if (isset($data[$key])) {
return $data[$key];
}
return false;
}
public function getDescription($description) {
// regex to find the words following : (or any other char)
// look for the variables, and do whatever handling you want if they're not found
// return whatever you want
// IF you don't want to do a regex, you can do the following
foreach ($this->data as $key => $value) {
$description = str_replace(":$key", $value, $description);
}
if (strpos(':', $description) !== FALSE) {
return $description;
}
return false; // or whatever error handling you want
}
}
$strings = new CustomStrings();
$strings->name = 'John';
$strings->age = 16;
$strings->sport = 'Football';
$description = $strings->getDescription("My name is :name, I am :age years old, I like :sport");
You will have all your variables stored in the CustomStrings object, with the proper keys, and instead of writing $name, you write :name.
You do the isset handling only once, in the getDescription function.
I didn't write the regex since I'm lazy. If you want to use : in your strings, replace it with something you won't be using.
Good luck!

Answer 2

If you need to have ALL variables defined, PHP's isset() supports multiple values, so you could do this
<?php
$name = "John Smith";
$age = "106";
$favAnimal = "pig";
$email = "john#smith.com";
$sport = "tennis";
if(isset($name, $age, $favAnimal, $email, $sport)) {
$userDescription = "My name is $name, I am $age years old, I like $sport.";
echo $userDescription; //Or do something else
}
?>

Answer 3

You should put them in array and use loop.
$data = array();
$data['name'] = "John Smith";
$data['age'] = "106";
$data['favAnimal'] = "pig";
$data['email'] = "john#smith.com";
$data['sport'] = "tennis";
$userDescription = "My name is $name, I am $age years old, I like $sport.";
$required_fields = array('name', 'age', 'favAnimal', 'email', 'sport');
if(checkData($data,$required_fields)) echo 'all fields are ok';
else echo 'not all fields are OK';
function checkData($data, $requiredFields)
{
foreach($requiredFields as $field)
{
if((array_key_exists($field, $data) && !empty($data[$field])) == false) return false;
}
return true;
}
Funcion check data takes 2 arguments both are arrays.
$data is the data to be checked.
$requiredFields is the array of required fields which needs to be set and musn't be empty

Answer 4

Why don't you store your strings in an array?
You could use a foreach loop then. This way you would have to use isset() just once!
$strings = new Array('string1', 'string2', 'string3')
foreach($strings as $str)
{
if(isset($str))
{
//do something..
}
}

Answer 5

One possible solution if you want have variables as you have and not use isset:
Define your string in this way:
$userDescription = "My name is [name], I am [age] years old, I like [sport].";
Or you dont have to update your string this way, you just change quotes from " to ' and variables will not be parsed.
Now, get all "variables" from your string (text inside [] from example above). For this use regular expression with (preg_split() or something else).
Now use those as variables of variables and test if they are not empty.
eg:
for ($i = 0; $i < counr($result); $i++)
{
if (($result[$i] == 'name') && (${$results[$i]} == "")) echo "Name is empty"
if (($result[$i] == 'age') && (is_int(${$results[$i]}) == false)) echo "Age is empty"
....
}
Above code is not working PHP, ist more or less pseudocode and steps how it can be done.

Answer 6

Another way is to use the E_NOTICE generated when undefined variables are in your string, that way, you automatically check ONLY for the variables in your string.
The problem is, you can't CATCH E_NOTICE, you have to use a custom error handler:
<?php
function handleError($errno, $errstr, $errfile, $errline, array $errcontext)
{
throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
}
$var1 = "one";
$var2 = "two";
$var4 = "four";
error_reporting(E_ALL);
set_error_handler('handleError');
try {
echo "Hey $var1, I like $var2 but not $var3 . Tell that to $var4";
//This will throw a Notice: Undefined variable: var3 in /t.php on line 8
} catch (Exception $e) {
echo "Well, it looks like some vars were not set.";
}
restore_error_handler()
?>
It is a bit ugly, but 100% automatic.