PHP Form Validation

Form Handling in PHP

Form Validation

• Why validate?: Prevent malicious input, ensure data consistency, and improve user experience
• Types of validation:
  • Client-side validation (JavaScript): Fast, but can be bypassed
  • Server-side validation (PHP): More secure, but slower
• PHP validation techniques:
  • Check for empty fields
  • Validate data formats (e.g., email, phone number)
  • Use regular expressions (regex) for pattern matching
  • Compare user input with expected values

Sanitize User Input

• Why sanitize?: Prevent SQL injection and cross-site scripting (XSS) attacks
• PHP sanitization functions:
  • htmlspecialchars(): Convert special characters to HTML entities
  • filter_var(): Validate and sanitize input data (e.g., email, URL)
  • trim(): Remove whitespace from input strings
  • stripslashes(): Remove backslashes from input strings
• Best practices:
  • Sanitize user input before storing it in a database
  • Use prepared statements with parameterized queries to prevent SQL injection
  • Avoid using mysql_* functions, which are deprecated and vulnerable to SQL injection

Form Handling in PHP

Form Validation

• Form validation is necessary to prevent malicious input, ensure data consistency, and improve user experience
• There are two types of form validation: client-side and server-side
• Client-side validation is faster but can be bypassed, while server-side validation is more secure but slower
• PHP validation techniques include:
  • Checking for empty fields
  • Validating data formats (e.g., email, phone number)
  • Using regular expressions (regex) for pattern matching
  • Comparing user input with expected values

Sanitizing User Input

• Sanitizing user input is necessary to prevent SQL injection and cross-site scripting (XSS) attacks
• PHP sanitization functions include:
  • htmlspecialchars(): Converting special characters to HTML entities
  • filter_var(): Validating and sanitizing input data (e.g., email, URL)
  • trim(): Removing whitespace from input strings
  • stripslashes(): Removing backslashes from input strings
• Best practices for sanitizing user input include:
  • Sanitizing user input before storing it in a database
  • Using prepared statements with parameterized queries to prevent SQL injection
  • Avoiding the use of mysql_* functions, which are deprecated and vulnerable to SQL injection