• When you create a form, you can decide which fields are required and which are optional.
  • Your decision is implemented in the PHP program.
  • You check the fields that require information.
  • If a required field is blank, you send a message to the user, indicating that the field is required, and then you redisplay the form.
• The general procedure to check for empty fields is:
• if ($last_name == "")
  {
       echo"You did not enter your last name. Last name is required.<br>\n";
       display the form;
       exit();
  }
  echo " Welcome to the Members Only Club. You may select from the menu below.<br>\n";
  display the menu;
• Notice the exit sttm, which ends the program.
  • Without the exit sttm, the program would continue to the statements after the if sttm.
  • In other words, without the exit sttm, the program would display the form and then continue to echo the welcome sttm and the menu as well.
• In many cases, you want to check all the fields in the form.
  • You can do this by looping through the array $_POST.
• The following sttms check the array for empty fields.
• foreach($_POST as $value)
  {
       if ( $value == "" )
       {
             echo "You have not filled in all the fields<br>\n";
             display the form;
             exit();
        }
  }
  echo "Welcome";
• When you redisplay the form, make sure that it contains the information that the user already typed in.
  • If users have to retype the correct information, they are likely to get frustrated and leave your Web site.
• In some cases, you might require the user to fill in most but not all fields.
  • For instance, you might request a fax number in the form or provide a field for a middle name, but they do not need to be filled out. They are not required.
  • In this case, you make an exception for fields that are not required, as follows:
• foreach($_POST as $field => $value)
  {
       if ( $field != "fax" and $field != "middle_name" )
       {
             if( $value == "" )
             {
                  echo "You have not filled in all the fields<br>\n";
                  display the form;
                  exit();
        }
  }
  echo "Welcome";
• 229 Notice that the outside if sttm is true only if the field is not the fax field and is not the middle name field.
  • For those two fields, the program does not use the inside if sttm, which checks for blank fields.
• In most cases, the program should create two arrays: one that contains the names of the fields that are inappropriately blank and one that contains the data that is correct, so you can display or store it. The need for an array of correct data is for checking the format of data and cleaning data which is discussed later.
• In some cases, you might want to tell the user exactly which fields need to be filled in.
  • The ( checkBlank.php ) program (which should not be run by itself) processes the form produced by the program ( displayForm01.php )
    • which has four fields, first_name, middle_name, last_name, phone.
    • All fields are required except middle_name.
• 229 Note that the book tells you to replace checkAll.php with checkBlank.php in the displayForm.php program.
  • I took care of that and saved it as ( displayForm01.php ).
• Then run ( displayForm01.php ), fill in the form, click the submit button, which runs checkBlank.php
• 230 to check for blanks, the program does the following:
  1. Sets up an array of field labels.
     • These labels are used as labels in the form, to display the list of missing information and to display the form.
  2. Loops thru all the variables passed from the form, checking for blanks.
  • The variables are in the array $_POST.
  • The field middle_name is not checked for blanks because it is not a required field.
  • Any blank fields are added to an array of blank fields, $blank_array.
  3. Checks whether any blank fields were found.
  • Check the nu8mber of items in $blank_array.
  4. If zero blank fields were found, jumps to the message; all required fields contain information.
  5. If one or more blank fields were found:
  1. Display an error message. This message explains to the user that some required information is missing.
  2. Displays a list of missing information. Loops through $blank_array and displays the label(s).
  3. Creates an array of good data. The data is cleaned so it can be safely displayed in the form.
  4. Redisplays the form. Because the form includes variable names in the value attribute, the information that the user prviously entered is retrieved from $good_data and displayed.
  5. Exits. Stops after the form displays. The user must click the submit button to continue.
• 231 Programs that process forms use information from the form and are not attended to be run by themselves.
  • They are only run when a user clicks the submit button.
• 231 Use the exit sttm wisely.
  • This prevents the program from running the next sttm, and display the welcome message after displaying the form.
• 231 The picture at the bottom of the page demonstartes how data that is blank and required displays a message at the top of the screen to let the user know it must be filled out.
  • Any fields with data gets redisplayed when the form is redisplayed, the data is not lost.

• expect typos and incorrect formatted fields, like not 5 or 9 digits in a zipcode.
• You must protect yourself from malicious users. Prevent them from entering HTML code into the fields.
• in a telephone number field, you would want to except -, spaces, perantheses,
  • and if you limit the phone number field to fourteen characters, international numbers may not get entered correctly.
• You check the input of a field by using regular expressions, whixh are patterns.
  • You compare the input of a field to the pattern to see if it matches.
  • If it does not match, the input information is incorrect, and must be flagged to let the user correct the data.
• Here is zudo code for checking a pattern:
  • if (!ereg("pattern",$variablename) )
    {
         echo error message;
         redisplay form;
         exit();
    }
    echo "Welcome";
  • Notice that the condition in the if sttm is negative.
    • The explamation mark (!) means not.
    • So the if sttm really means, if the variable does not match the pattern, execute the if block.
• 233 Suppose you want to check an input field that contains the user's last name.
  • You can expect names to contain letters, not numbers, an apostrophe, hyphen, and a space.
  • You can also set a limit of 50 characters.
  • You can use the following code:
  • if (!ereg("[A-Za-z' -]{1-50}",$last_name) )
    {
         echo error message;
         redisplay form;
         exit();
    }
    echo "Welcome";
  • Since we want to include the hyphen(-) as an alowable character,
    • we must place it between the square brackets [ ] at the beginning or end of the list,
    • otherwise it may be interpreted as the range between two characters, such as A-Z.
• 233 You also need to check multiple choice fields because even though multiple choice fields prevent honest people from making mistakes, it does not prevent clever users with malicious intentions from entering unexpected data into fields.
  • You can check multiple choice fields for acceptable output with the following type of regex:
  • if (!ereg("(male|female)",$gender) )
  • If the field contains anything except male or female, the if block executes.
• 233 So far we learned how to check every required field to make sure they are not blank.
  • You also have to verify that the fields have acceptable format.
  • checkAll03.php does that for us.
  • displayForm03.php is a modified version of the previously used displayForm01.php that utilizes checkAll03.php
    • in the form action='check.php' sttm as follows:
    • gg echo "<form action='check.php' method='POST'>
    • Then run ( displayForm03.php ), fill in the form, and click the submit button, which runs the checkAll03.php program.
  • here are the differences between the listed program from pages 229-230 and the current checkAll03.php listed on pages 234-235:.
    • This program creates two arrays for problem data.
      • It creates $blank_array, as did the previous listing.
      • But this program also creates $bad_format for fields that contain data in unacceptable format.
    • This program loops thru $bad_format to create a separate list of problem data.
      • If any fields are blank, it creates one error message and a list of required blank fields,
        • as the previous listing did.
      • If any fields are in an unacceptable format,
        • this program also creates a second error message and a list of problem fields.
  • This form ( displayForm03m.php ) checks for one character entered in the middle name.

• You can use more than one submit button in a form. ( displayTwoButtons.php )
  • For instance, in a customer order form,
    • you can have one submit button to process an order, and another submit button to cancel an order.
  • In the ( displayTwoButtons.php ) program there are two submit buttons,
    • one to display an address and another to display a phone number.
• However, you can only list one program in the action=programname part of the form tag,
  • meaning that two buttons run one program.
  • PHP solves this problem, by using PHP to process the form differently, depending on which button the user clicks.
• The ( displayTwoButtons.php ) program displays a form with two buttons.
• Here's the code:
• <?php
  echo "<form action='processTwoButtons01.php' method='POST'>
  Last Name: <input type='text' name='last_name'
  maxlength='50'><br>
  <input type='submit' name='display_button'
  value='Show Address'>
  <input type='submit' name='display_button'
  value='Show Phone Number'>
  </form>";
  ?>
• Notice that the two submit buttons have the same name 'display_button',
  • but each has a different value, 'Show Address' and 'Show Phone Number'.
• Whichever button the user clicks sets the value for $display_button.
  • The program processTwoButtons01.php processes the form.
• The program executes different sttms, depending on which button is clicked.
  • If the user clicks the button for the address, the program outputs the address for the name submitted in the form.
  • If the user clicks the 'Show Phone Number' button, the program outputs the phone number for the name submitted in the form.
• Here is the programming logic:
• if ($_POST['display_button'] == "Show Address")
  {
  $query = "SELECT street,city,state,zip FROM Member
  WHERE lastName='$_POST[last_name]'";
  $result = mysqli_query($cxn,$query)
  or die ("Couldn't execute query.");
  $row = mysqli_fetch_assoc($result);
  extract($row);
  echo "$street<br>$city, $state $zip<br>";
  }
  else
  {
  $query = "SELECT phone FROM Member
  WHERE lastName='$_POST[last_name]'";
  $result = mysqli_query($cxn,$query)
  or die ("Couldn't execute query.");
  $row = mysqli_fetch_assoc($result);
  echo "Phone: {$row['phone']}";
  }
• The if sttm checks the display_button variable for "Show Address"
  • If that is true the query retreives the address.
  • If that is false, the query retreives the phone number.

Results

• It checks the data from the form for blank fields and incorrect formats, asking the user to retype the data when it finds a problem.
• If the data is okay, the program trims the data, cleans it, and stores it in the database.

• A function that stores data from a form can be very useful.
• The following is a function that stores all the data in a form. displayPhone_func01.php

• At the begining, the function checks that the data passes to it is actually an array.
• If $formdata is not an array, the function stops and returns FALSE.

• Also notice that this function assumes you are already connected to the MySQL server and have selected the correct database.
• The database connection is passed to the function.

• Furthermore, this function works for any form as long as the field names in the form are the same as the column names in the database table.
• If the function is unable to execute the query, it stops executuin at that point and prints the error message "Couldn't execute query".
• If the query might fail in certain circumstances, you need to take these into consideration.