PHP Forms Using Form Elements with Multiple Options

PHP Forms

Using Form Elements with Multiple Options

Problem

You have form elements that let a user select multiple choices, such as a drop-down menu or a group of checkboxes, but PHP sees only one of the submitted values.

Solution

Example  Naming a checkbox group

      <input type="checkbox" name="boroughs[]" value="bronx"> The Bronx
      <input type="checkbox" name="boroughs[]" value="brooklyn"> Brooklyn
      <input type="checkbox" name="boroughs[]" value="manhattan"> Manhattan
      <input type="checkbox" name="boroughs[]" value="queens"> Queens
      <input type="checkbox" name="boroughs[]" value="statenisland"> Staten Island


Example  Handling a submitted checkbox group

      print 'I love ' . join(' and ', $_POST['boroughs']) . '!';

Discussion

Putting [] at the end of the form element name tells PHP to treat the incoming data as an array instead of a scalar. When PHP sees more than one submitted value assigned to that variable, it keeps them all. If the first three boxes were checked, it’s as if you’d written the code at the top of your program.

Example   Code equivalent of a multiple-value form element submission

     $_POST['boroughs'][] = "bronx";
     $_POST['boroughs'][] = "brooklyn";
     $_POST['boroughs'][] = "manhattan";

A similar syntax also works with multidimensional arrays. For example, you can have a checkbox such as <input type="checkbox" name="population[NY][NYC]" value="8336697">. If checked, this form element sets $_POST['population']['NY'] ['NYC'] to 8336697.