How to write short PHP functions that work together - php

Question

I want to modularize functions, but this is not working...
class Review {
public function show_report($db, $id){
// Query the DB on $id
$x = $this->get_survey($db, 1);
$y = $this->get_survey($db, 2);
// Use x and y to build a report
return $a_report;
}
private function get_survey($db, $n){
// Query the DB for a certain survey number
if($n == 1){
// Perform some logic
} else {
// Perform some other logic
}
return $a_survey;
}
};
Using the class like this..
<?php
include_once('api/Review.class.php');
$r = new Review();
?>
<p>
<?php
echo Review::show_report($db, $id);
?>
</p>
PHP throws this:
Fatal error: Using $this when not in object context in Review.class.php
Thanks for the help!

Answer 1

Your design pattern is good, you just have a syntax error. You have missed the $ sign on your method calls in show_report(), it should look like this:
public function show_report($db, $id){
// Query the DB on $id
$x = $this->get_survey($db, 1);
$y = $this->get_survey($db, 2);
// Use x and y to build a report
return $a_report;
}
Also, the semicolon at the end of the class is unnecessary.
Finally, as another person mentioned, you need to call show_report with parameters, like this:
echo $r->show_report($db, $id);

Answer 2

Inside your function show_report($db, $id) is the this pointer without the prefixing $ sign which causes the syntax error. Additionally in the second part the function isn't called with parameters.
The function has to look like that:
public function show_report($db, $id){
// Query the DB on $id
$x = $this->get_survey($db, 1);
$y = $this->get_survey($db, 2);
// Use x and y to build a report
return $a_report;
}

Answer 3

echo $r->show_report;
In this example, you are attempting to call the function with no arguments. If this is really what you are doing, that would be at least one problem.
Instead, call the function with arguments:
echo $r->show_report('foo', 1);

Answer 4

Thank you all. I fixed all the syntax errors, thanks to https://stackoverflow.com/a/19258788/1004107. This is the root of the issue I do believe:
<?php
include_once('api/Review.class.php');
$r = new Review();
?>
<p>
<?php
echo Review::show_report($db, $id);
?>
</p>
Should be...
<?php
include_once('api/Review.class.php');
$r = new Review();
?>
<p>
<?php
echo $r->show_report($db, $id);
?>
</p>
And this is do to static context? Please comment.