Publishers of technology books, eBooks, and videos for creative people

Home > Articles > Web Design & Development > PHP/MySQL/Scripting

This chapter is from the book

Handling HTML Forms with PHP Redux

All of the examples in this chapter and the preceding one used two separate scripts for handling HTML forms: one that displayed the form and another that received it. While there's certainly nothing wrong with this method, there are advantages to having the entire process in one script. To have one page both display and handle a form, use a conditional.

if (/* form has been submitted */) {
   // Handle it.
} else {
   // Display it.
}

To determine if the form has been submitted, I normally check that a $_POST variable is set (assuming that the form uses the POST method, of course). For example, you can check $_POST['submitted'], assuming that's the name of a hidden input type in the form.

if (isset($_POST['submitted'])) {
   // Handle it.
} else {
   // Display it.
}

If you want a page to handle a form and then display it again (e.g., to add a record to a database and then give an option to add another), use

if (isset($_POST['submitted'])) {
   // Handle it.
}
// Display the form.

Using the preceding code, a script will handle a form if it has been submitted and display the form every time the page is loaded.

To demonstrate this important technique, I'll start by creating a sales calculator. Later in this chapter this same method will be used with a registration page.

To handle HTML forms

  1. Create a new PHP document in your text editor ( Script 3.5 ).
    <?php # Script 3.5 - calculator.php
    $page_title = 'Widget Cost Calculator';
    include ('./includes/header.html');
    
    03fig11.jpg

    Script 3.5 The calculator.php script both displays a simple form and handles the form data, performing the calculations.

    This, and all the remaining examples in the chapter, will use the same templating system as the index.php page. The beginning syntax of each page will therefore be the same, but the page titles will differ.

  2. Write the conditional for handling the form.
    if (isset($_POST['submitted'])) {
    

    As I mentioned previously, if the $_POST['submitted'] variable is set, I know that the form has been submitted and I can process it. This variable will be created by a hidden input in the form that will act as a submission indicator.

  3. Validate the form.
    if ( is_numeric($_POST['quantity']) 
    && is_numeric($_POST['price']) && 
    is_numeric($_POST['tax']) ) {
    

    The validation here is very simple: it merely checks that three submitted variables are all numeric types. You can certainly elaborate on this, perhaps checking that the quantity is an integer (in fact, in Chapter 10, "Web Application Security," you'll find a variation on this script that does just that). If the validation passes all of the tests, the calculations will be made; otherwise, the user will be asked to try again.

  4. Perform the calculations.
    $taxrate = $_POST['tax'] / 100;
    $total = ($_POST['quantity'] *
    $_POST['price']) * ($taxrate + 1);
    

    The first line changes the tax value from a percentage (say, 5%) to a decimal (.05), which will be needed in the subsequent calculation. The second line starts by multiplying the quantity times the price. This is then multiplied by the tax rate (.05) plus 1 (1.05). This last little trick is a quick way to calculate the total cost of something with tax (instead of multiplying the tax rate times the total and then adding this amount to the total).

  5. Print the results.
    echo '<h1 id="mainhead">Total Cost</h1>
    <p>The total cost of purchasing ' . $_POST['quantity'] . ' widget(s) at $' . number_format ($_POST ['price'], 2) . ' each, including
     a tax rate of ' . $_POST['tax'] . '%, is $' . number_format ($total, 2) . '.</p><p><br /></p>';
    

    All of the values are printed out, formatting the price and total with the number_format() function.

  6. Complete the conditionals and close the PHP tag.
      } else {
         echo '<h1
    id="mainhead">Error!</h1>
         <p class="error">Please enter a valid quantity, price, and tax.</p><p><br /></p>';
      }
    }
    ?>
    

    The else clause completes the validation conditional, printing an error if the three submitted values aren't all numeric. The final closing curly brace closes the isset($_POST['submitted']) conditional. Finally, the PHP section is closed so that the form can be created without using print() or echo().

  7. Display the HTML form.
    <h2>Widget Cost Calculator</h2>
    <form action="calculator.php" method="post">
      <p>Quantity: <input type="text" name="quantity" size="5" maxlength="10" /></p>
      <p>Price: <input type="text" name="price" size="5" maxlength="10" /></p>
      <p>Tax (%): <input type="text" name="tax" size="5" maxlength="10" /></p>
      <p><input type="submit" name="submit" value="Calculate!"
    /></p>
      <input type="hidden" name="submitted" value="TRUE" />
    </form>
    

    The form itself is fairly obvious, containing only two new tricks. First, the action attribute uses this script's name, so that the form submits back to this page instead of to another. Second, there is a hidden input called submitted with a value of TRUE. This is the flag variable whose existence will be checked to determine whether or not to handle the form (see the main condition).

  8. Include the footer file.
    <?php
    include ('./includes/footer.html');
    ?>
    
  9. Save the file as calculator.php, upload to your Web server, and test in your Web browser ( Figures 3.7, 3.8 , and 3.9 ).
    03fig12.gif

    Figure 3.7 The HTML form, upon first viewing it in the Web browser.

    03fig13.gif

    Figure 3.8 The page performs the calculations, reports on the results, and then redisplays the form.

    03fig14.gif

    Figure 3.9 If one of the submitted values is not numeric, an error message is displayed.

Peachpit Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Peachpit and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Peachpit products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email ask@peachpit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by Adobe Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.peachpit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020