gavinmdev
IoT Framework Developer
2
MONTHS
2 2 MONTHS OF SERVICE
LEVEL 1
300 XP
This article delves into an exploration of the causes and solutions for the PHP Fatal Error that reads 'PHP Fatal error: Uncaught Error: Using $this when not in object context'. If you are currently encountering this error during the development phase of your PHP project, this article aims to provide you with insights into understanding the error and guidance on how to prevent and resolve it.
What is PHP Fatal Error means?
The PHP programming language encompasses various types of errors that can occur when writing and executing code in this language. One of these error categories is known as Fatal Error. Fatal Errors arise from attempting to invoke non-existing functions, variables, or methods, and they can lead to the termination or crashing of the program. In addition to the Fatal Error message that we are investigating in this article, errors can be thrown such as the following:
- Fatal error: Call to a member function on a non-object
- PHP Fatal error: Uncaught TypeError: implode(): Argument
- Fatal Error: Cannot Redeclare class
Why does the PHP Fatal error: Uncaught Error: Using $this when not in object context
occurs?
In PHP, the error message PHP Fatal error: Uncaught Error: Using $this when not in object context is triggered when the $this
variable, which serves as a special variable referring to the current object, is utilized outside the scope of an object or class. This error can also occur when attempting to access the $this
variable within a static function of an object or class, which is not permitted. In PHP classes, we employ $this
to refer to the current object within non-static members. If you need to reference static members, you should use self
instead of $this
.
How to Fix PHP Fatal error: Uncaught Error: Using $this when not in object context
?
This PHP Fatal error can be resolved by ensuring that when you use the $this
variable, your code or script must be located within the context of an object or class.
Scenario #1:
Here's a sample snippet that simulate the error to occur.
- <?php
- class
MyClass{
- // Defining Sample Protected Variable
- protected
$var1
;
- // defining a default valur to the variable
- public
function
__construct(
)
{
- $this
->
var1
=
"Lorem Ipsum"
;
- }
- // static class object that attempts to use $this
- public
static function
get_variable(
)
{
- echo
$this
->
var1
;
- }
- }
- // Initialize class
- $myClass
=
new
MyClass(
)
;
- // Output variable
- print_r
(
$myClass
::
get_variable
(
)
)
;
- ?>
In the given code snippet, it's evident that we are making an attempt to retrieve or display the var1
property of the MyClass
class. Running this script will result in a Fatal Error since we are accessing the var1
variable using $this
within the static property or method of the class.
Solution 1
In the scenario presented above, we can resolve the error by converting the variable in question into a static one and accessing it using self. To gain a clearer understanding, refer to the following code snippet:
- <?php
- class
MyClass{
- // Defining Sample Protected Variable
- static protected
$var1
;
- // defining a default valur to the variable
- public
function
__construct(
)
{
- self
::
$var1
=
"Lorem Ipsum"
;
- }
- // static class object that attempts to use $this
- public
static function
get_variable(
)
{
- echo
self
::
$var1
;
- }
- }
- // Initialize class
- $myClass
=
new
MyClass(
)
;
- // Output variable
- print_r
(
$myClass
::
get_variable
(
)
)
;
- ?>
Solution 2
Furthermore, the initial scenario can be rectified by transforming the static method into a non-static member method of the class. Please refer to the following code snippet for a step-by-step guide on how to achieve this:
- <?php
- class
MyClass{
- // Defining Sample Protected Variable
- protected
$var1
;
- // defining a default valur to the variable
- public
function
__construct(
)
{
- $this
->
var1
=
"Lorem Ipsum"
;
- }
- // non-static class object that attempts to use $this
- public
function
get_variable(
)
{
- echo
$this
->
var1
;
- }
- }
- // Initialize class
- $myClass
=
new
MyClass(
)
;
- // Output variable
- print_r
(
$myClass
->
get_variable
(
)
)
;
- ?>
Scenario #2
Another cause for the Fatal error: Uncaught Error: Using $this when not in object context
to occur is attempting to use the $this
special variable outside of the object. Please review the provided code snippet for this specific scenario:
- <?php
- class
MyClass{
- protected
$var1
;
- public
function
__construct(
)
{
- $this
->
var1
=
"Lorem Ipsum"
;
- }
- }
- $myClass
=
new
MyClass(
)
;
- function
get_variable(
)
{
- global
$myClass
;
- return
$this
->
var1
;
- }
- // Output variable
- print_r
(
get_variable(
)
)
;
- ?>
Solution 1
In the second scenario, the error can be resolved by utilizing the defined class variable name instead of the $this
variable, especially since the get_variable() function is not a member method of any object. Please refer to the PHP code snippet below for a clearer understanding:
- <?php
- class
MyClass{
- public
$var1
;
- public
function
__construct(
)
{
- $this
->
var1
=
"Lorem Ipsum"
;
- }
- }
- $myClass
=
new
MyClass(
)
;
- function
get_variable(
)
{
- global
$myClass
;
- return
$myClass
->
var1
;
- }
- // Output variable
- print_r
(
get_variable(
)
)
;
- ?>
Solution 2
Moreover, extending the MyClass into another class or object and moving the get_variable() method to this object is another solution to the problem. In this scenario, the $this
variable becomes usable, allowing access to the value of the var1 variable outside the main class.
- <?php
- class
MyClass{
- public
$var1
;
- public
function
__construct(
)
{
- $this
->
var1
=
"Lorem Ipsum"
;
- }
- function
get_variable(
)
{
- //
- }
- }
- class
NextClass extends
MyClass{
- public
function
get_variable(
)
{
- return
$this
->
var1
;
- }
- }
- $NextClass
=
new
NextClass(
)
;
- // Output variable
- print_r
(
$NextClass
->
get_variable
(
)
)
;
- ?>
Conclusion
In simpler terms, the Fatal error: Uncaught Error: Using $this when not in object context error message in PHP occurs when we try to utilize the $this
(a special variable in PHP) outside of an object or class. This error can also happen when we employ this variable within a static member method or variable of the current object or class. The solution to this error lies in ensuring that we avoid the causes that lead to its occurrence.
And there you have it! I trust that this article on rectifying the 'Fatal error: Uncaught Error: Using $this when not in object context' will be beneficial for your current situation during your PHP project development phase.
Explore more on this webstire for more Free Source Codes, Tutorials, Articles about programming languages.
Happy Coding =)