Quick Guide To PHP Filters
PHP filters are used for validating and sanitizing user input. PHP filters help web developers ensure that input from users is safe and meets certain requirements, such as a valid email address, a numeric value, or a specific format.
In this article, we’ll discuss what PHP filters are, how they work, and how to use them effectively in your PHP code.
- Quick Guide To PHP Filters:
- What are PHP Filters?:
- Why Use Filters?:
- PHP Filter Extension:
- PHP filter_var() Function:
- String Sanitization:
- Validate an Integer:
- IP Address Validation:
- Validate IPv6 Address:
- Email Address Validate & Sanitize:
- URL Validation and Sanitization:
- Validate Query String URLs:
- Remove ASCII Characters:
- Benefits Of PHP Filters:
What are PHP Filters?
PHP filters are built-in functions that can be used to validate and sanitize user input. The purpose of filters is to ensure that data entered by users is safe and conforms to certain standards.
PHP filters provide a simple and effective way to validate and sanitize user input, which is essential for security and usability of web applications.
There are plenty of PHP filter functions available that can be used to validate and sanitize data in a quick and efficient manner.
Filters can be classified into two main categories validation filters and sanitization filters.
Why Use Filters?
There are many web applications that receive input from external sources. Input/data can be:
- Input from a form provided by the user.
- Cookie information.
- Data from web services.
- Variables on the server.
- Results of a database query.
- Validate external data always!
When you use PHP filters, you can ensure the input to your application is correct and you don’t have to worry about it!
PHP Filter Extension
As part of the validation and sanitization of external input, PHP filters are used.
PHP filter extension has many functions that are required to verify user input and is designed to simplify and speed up the process of data validation for PHP programs.
Before using PHP filters, it is essential to specify the filter type, such as validation or sanitization. Additionally, you should provide the input data you wish to filter along with any necessary options or parameters required by the filter.
This function, filter_list(), can be used to list the features that the PHP filter extension offers, like:
Example:
PHP filter_var() Function
Using the filter_var() function, you can verify and sanitize data. A single variable can be filtered by the filter_var() function using the specified filter.
There are two pieces of information that are required:
- Variables to check.
- Check type to be used in the assessment.
String Sanitization
A sanitization process involves the removal of characters from foreign input that are illegal or unsafe.
The following example shows how to remove all HTML tags from a string by using the filter_var() function:
Example:
Validate an Integer
Example:
Example:
The example below shows how you can use the filter_var() function and the FILTER_VALIDATE_INT filter in PHP to validate an integer within a range.
The options parameter allows you to specify the range for the integer to be validated.
Example:
Here, let’s take an example of validating the age of adults from 18 to 60 using the filter_var() function:
Example:
IP Address Validation
Example:
Validate IPv6 Address
Example:
Example:
Email Address: Validate & Sanitize
To validate email address, we will use the filter_var() function to first remove all illegal characters from the $email_add variable, and then we will check if the email address is valid using the following syntax:
Example:
URL Validation and Sanitization
In the following example, we use the filter_var() function in order to first remove all illegal characters from a URL, and then determine whether $url is a valid URL based on the removed characters:
Example:
Validate Query String URLs
Example:
Example:
Remove ASCII Characters
This example illustrates how to sanitize a string by using the filter_var() function.
All HTML tags in the string, as well as all characters with ASCII values > 127, will be removed by this function:
Example:
Example:
Benefits Of PHP Filters
PHP filters provide significant benefits for web application development by enhancing security, improving data quality, saving time and costs, improving user experience, and providing flexibility and customizability.
- PHP filters help prevent security vulnerabilities such as SQL injection and cross-site scripting (XSS) attacks by validating and sanitizing user input. This significantly reduces the risk of data breaches and unauthorized access to sensitive information.
- By validating user input against a set of rules, PHP filters help ensure that data entered by users is accurate and meets specific standards. This results in better data quality, which can improve the overall functionality and usability of web applications.
- It can save your time and money by reducing the need for manual input validation and sanitization. With PHP filters, you can easily implement a standard set of rules to validate and sanitize user input, which can save time and reduce development costs.
- You can ensure that user input is formatted and validated correctly, providing a better user experience for users. This can increase user satisfaction and retention, leading to better business outcomes.
- It provides a flexible and customizable way to validate and sanitize user input. You and other web developers can customize filters to meet specific requirements and can easily modify and extend them as needed.
