Slide môn học PHP session 3 form handling in PHP

Form Handling in PHP Session Review - I     PHP is a general purpose scripting language used for developing dynamic web pages PHP is developed from C-modules PHP has become a popular tool for e-commerce PHP 4.0 includes supportive features for the following:  Security for user inputs  Web servers  New constructions for  HTTP sessions languages  Output buffering PHP / Session / Slide of 21 Review - II  PHP is used for generating the following:     Files in formats like PDF and HTML Emails Graphical images like GIF and PNG PHP script has the following tags: : End tag HTTP protocol is divided into following three parts:      Request and response line HTTP header Body of the protocol PHP / Session / Slide of 21 Review - III    header( ) function is used to generate the HTTP headers It sends the HTTP commands to the server through HTTP protocols PHP uses tools for developing and designing web pages These tools are the program text editors Gedit is the most popular text editor used for programming on Linux platform PHP / Session / Slide of 21 Objectives     Use the GET Method Use the POST Method Retrieve data from forms using variables Use hidden fields PHP / Session / Slide of 21 Forms - I    Form provides medium of interface between the client and server PHP provides us with the powerful feature of handling forms PHP provides built-in support for collecting data from a HTML form PHP / Session / Slide of 21 Forms - II   On submission of the form, the information is sent to the Web server, which in turn passes the information to the PHP script engine Script engine processes the information, manipulates it, and sends the output back to the Web browser PHP / Session / Slide of 21 Forms - III  A form consists of the following attributes:  Action: Specifies the Uniform Resource Locator (URL) that will process the form data and send the feedback  Method: Specifies the method by which data is to be sent to the URL PHP / Session / Slide of 21 GET Method - I    Specifies the Web browser to send all the user information as part of the URL Question mark is added at the end of the URL, which indicates the ending of the URL and the beginning of the form information Information on the form is transmitted in the structure of name/value pairs to the URL PHP / Session / Slide of 21 GET Method - II      Multiple name/value pairs can be sent to the URL by separating each pair with the ampersand (&) sign Name/value pairs are similar to variables Once name/value are on the Web server for processing, PHP make them available as variables Name/value pairs sent to the URL is a query string GET Method transmits only limited data PHP / Session / Slide 10 of 21 POST Method - I   Specifies the Web browser to send all the user information through the body of the HTTP request Transmits more information through the body of the HTTP request, as there no physical limit on the amount of information passed through the body of the HTTP request PHP / Session / Slide 11 of 21 POST Method - II   Information sent by the POST method is not encrypted As a result, it is easily accessible to a hacker In order to make the information to be secure, it is necessary to establish a secure server connection PHP / Session / Slide 12 of 21 Difference in GET and POST - I    GET method sends information through the URL whereas the POST method sends information through the body of the HTTP request GET method is less secure as all the users are able to view the transmitted information in the URL GET method enables to transmit less amount of information as compared to the POST PHP / Session / Slide 13 of 21 Difference in GET and POST - II   In the GET method, the pages loaded are carefully book-marked, whereas in POST method the pages loaded are not properly book-marked GET method retrieves the information whereas the POST method manipulates the information on the Web server PHP / Session / Slide 14 of 21 Retrieving Data Using GET Method  The syntax to retrieve the data if we have used the GET method is: $varname = $_GET[‘variable’]; Where,  varname - Specifies the name of the variable in which the data is to be stored  _GET[‘variable’]- Specifies the name of the input variable PHP / Session / Slide 15 of 21 Retrieving Data Using POST Method To retrieve the data if we have used the POST method, the syntax is: $varname=$_POST[‘variable’]; Where,    varname - Specifies the name of the variable in which the data is to be stored POST[‘variable’] - Specifies the name of the input variable PHP / Session / Slide 16 of 21 Hidden Fields - I     Hidden form field enables to pass information to the Web server Hidden field is similar to the text field The difference is that the user cannot view the hidden field and its contents To view whether the form contains the hidden field, the user needs to view the HTML source code of the form PHP / Session / Slide 17 of 21 Hidden Fields - II  The syntax to define the hidden filed is: Where,  INPUT TYPE - Specifies that the field is hidden  NAME - Specifies the name of the hidden field  VALUE - Specifies the value as it appears on the form PHP / Session / Slide 18 of 21 Summary - I      Form provides a medium of interaction where users can fill in data PHP has a built-in support for collecting data from a HTML form Information from the form is automatically available to the script engine Script engine processes the information Server recognizes the form as a collection of codes PHP / Session / Slide 19 of 21 Summary - II     Attributes of a form as are as follows:  Action  Method In order to create a Form, we use the opening and closing tags Elements placed between the tags, automatically becomes a part of the form The GET method specifies the browser to send the values the user placed on the form to the URL PHP / Session / Slide 20 of 21 Summary - III    POST method informs the browser to send the values the user placed on the form to the PHP script engine in the body of the HTTP request Hidden form fields enables form developers to pass information, from a form to a script, or from one form to another, before being passed to a script Hidden form fields are not visible to users PHP / Session / Slide 21 of 21 [...]... from a HTML form Information from the form is automatically available to the script engine Script engine processes the information Server recognizes the form as a collection of codes PHP / Session 3 / Slide 19 of 21 Summary - II     Attributes of a form as are as follows:  Action  Method In order to create a Form, we use the opening and closing tags Elements placed between the tags,... PHP / Session 3 / Slide 12 of 21 Difference in GET and POST - I    GET method sends information through the URL whereas the POST method sends information through the body of the HTTP request GET method is less secure as all the users are able to view the transmitted information in the URL GET method enables to transmit less amount of information as compared to the POST PHP / Session 3 / Slide 13. .. of the form The GET method specifies the browser to send the values the user placed on the form to the URL PHP / Session 3 / Slide 20 of 21 Summary - III    POST method informs the browser to send the values the user placed on the form to the PHP script engine in the body of the HTTP request Hidden form fields enables form developers to pass information, from a form to a script, or from one form to... user information through the body of the HTTP request Transmits more information through the body of the HTTP request, as there no physical limit on the amount of information passed through the body of the HTTP request PHP / Session 3 / Slide 11 of 21 POST Method - II   Information sent by the POST method is not encrypted As a result, it is easily accessible to a hacker In order to make the information... define the hidden filed is: Where,  INPUT TYPE - Specifies that the field is hidden  NAME - Specifies the name of the hidden field  VALUE - Specifies the value as it appears on the form PHP / Session 3 / Slide 18 of 21 Summary - I      Form provides a medium of interaction where users can fill in data PHP has a built -in support for collecting... the input variable PHP / Session 3 / Slide 16 of 21 Hidden Fields - I     Hidden form field enables to pass information to the Web server Hidden field is similar to the text field The difference is that the user cannot view the hidden field and its contents To view whether the form contains the hidden field, the user needs to view the HTML source code of the form PHP / Session 3 / Slide 17 of 21 Hidden... PHP / Session 3 / Slide 13 of 21 Difference in GET and POST - II   In the GET method, the pages loaded are carefully book-marked, whereas in POST method the pages loaded are not properly book-marked GET method retrieves the information whereas the POST method manipulates the information on the Web server PHP / Session 3 / Slide 14 of 21 Retrieving Data Using GET Method  The syntax to retrieve the... variable in which the data is to be stored  _GET[‘variable’]- Specifies the name of the input variable PHP / Session 3 / Slide 15 of 21 Retrieving Data Using POST Method To retrieve the data if we have used the POST method, the syntax is: $varname=$_POST[‘variable’]; Where,    varname - Specifies the name of the variable in which the data is to be stored POST[‘variable’] - Specifies the name of the input... in the body of the HTTP request Hidden form fields enables form developers to pass information, from a form to a script, or from one form to another, before being passed to a script Hidden form fields are not visible to users PHP / Session 3 / Slide 21 of 21