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PHP Build a Basic PHP Website (2018) Building a Media Library in PHP Working with _GET Variables

Posted by Kristian Woods
Kristian Woods
23,414 Points

I'm trying to understand the $_GET function in PHP

I'm trying to wrap my head around this $_GET function

1) If you add a question mark at the end of a URL e.g. "?category=books" - the word after the question mark - "category", becomes a variable and the word "books", becomes its value

2) The function takes a string variable name - $_GET["category"]

3) The function isset(), checks for a variable "category" in the URL

4) If the variable exists in the URL, the $_GET function takes the value from the variable - in this case, "books"

5) You can then use a conditional statement to see what the value of "category" is, and run a code block

<?php
if(isset($_GET["category"])) {
  if($_GET["category"] == 'books') {
    $pageTitle = 'Books';
  } else if ($_GET["category"] == 'music') {
    $pageTitle = 'Music';
  } else if ($_GET["category"] == 'movies') {
    $pageTitle = 'Movies';
  }
}
?>

is this correct?

thanks

2 Answers

Miguel Canas
seal-mask
.a{fill-rule:evenodd;}techdegree
Miguel Canas
Python Development Techdegree Student 11,470 Points
Miguel Canas
.a{fill-rule:evenodd;}techdegree
Miguel Canas
Python Development Techdegree Student 11,470 Points

Hi Kristian,

You're definitely on the right track but just to clarify a few things:

I'm trying to wrap my head around this $_GET function

  • $_GET is not a function, it's an associative array.

1) If you add a question mark at the end of a URL e.g. "?category=books" - the word after the question mark - "category", becomes a variable and the word "books", becomes its value

  • Yes.

2) The function takes a string variable name - $_GET["category"]

  • Looping back to the first statement, $_GET is an associative array, not a function. An array holds a collection of variables, where as a function is for executing a block of code.

3) The function isset(), checks for a variable "category" in the URL

  • Yes, mostly. isset(...) takes any variable you pass to it, and determines if it's value is NULL or not. For example:
/* given the url http://www.mywebsite.com/mypage.php?category=books */
isset($_GET["category"]); // returns true, because category is a parameter that gets passed to the $_GET array

isset($_GET["foobar"]); // returns false, because foobar is not a parameter, so it does not exist in the $_GET array

isset($myVar); // returns false because $myVar is not defined.

4) If the variable exists in the URL, the $_GET function takes the value from the variable - in this case, "books"

  • Yep, but to clarify the terminology: "If the parameter exists in the URL, the $_GET array takes the value from the parameter"

5) You can then use a conditional statement to see what the value of "category" is, and run a code block

  • Precisely!

Here are some documentation links on the relevant topics:

Hope that's helpful.

Nicholas Mercer
Nicholas Mercer
2,319 Points
Nicholas Mercer
Nicholas Mercer
2,319 Points

Kristian,

You're 100% correct and that code will work without any issues! :) If you need help modifying it or adding more, let me know.

-Nick