PHP selection based on previous selection

Question

I have 2 functions in PHP, one of them displays the ISBN and the title of a book and the other displays the editions that exist in the database based on the ISBN selected on the previous selection.

Here are the 2 functions:

ISBN - Book dropdown list:

    <?php include ("includes/connections.php");
function dropdown($intIdField, $strNameField, $strTableName, $strOrderField, $strNameOrdinal, $strMethod="asc") {
   echo "<select name=\"$strNameOrdinal\" onchange=\"selection($id)\">\n";
   echo "<option value=\"NULL\">Select Value</option>\n";



   $strQuery = "select $intIdField, $strNameField
               from $strTableName
               order by $strOrderField $strMethod";

   $rsrcResult = mysql_query($strQuery);

   while($arrayRow = mysql_fetch_assoc($rsrcResult)) {
      $strA = $arrayRow["$intIdField"];
      $strB = $arrayRow["$intIdField"] . " - " . $arrayRow["$strNameField"];
      echo "<option value=\"$strA\">$strB</option>\n";
   }

   echo "</select>";
}
?>

Edition dropdown list:

<?php include ("includes/connections.php");
function dropdownEdition($intId1Field, $intId2Field, $strTableName, $strOrderField, $strNameOrdinal, $strMethod="asc") {

    $intId2Field = $GLOBALS['book'];
   var_dump($intId2Field);
   var_dump($_POST["book"]);

   echo "<select name=\"$strNameOrdinal\">\n";
   echo "<option value=\"NULL\">Select Value</option>\n";



   $strQuery = "SELECT $intId1Field, $intId2Field
               FROM $strTableName
               ORDER BY $strOrderField $strMethod";

   $rsrcResult = mysql_query($strQuery);

   while($arrayRow = mysql_fetch_assoc($rsrcResult)) {
      $strA = $arrayRow["$intId1Field"];
      echo "<option value=\"$strA\">$strA</option>\n";
   }

   echo "</select>";
   }

?>

What I have been trying to do is pass the ISBN selected on the previous selection with a onchange function which would return the ISBN of the book but it failed a lot.

<?php

    function selection($id){
            echo $id;
        }

?>

I know I'm terrible at this but I don't know what else to do if you could point me to a direction it would be much appreciated.

I would prefer a PHP solution rather than a JavaScript one if possible.

you can't do that without using javascript

Bob
– Bob

2012-06-08 18:10:14 +00:00
Commented Jun 8, 2012 at 18:10 — Bob
– Bob, Commented Jun 8, 2012 at 18:10

score 2 · Accepted Answer · 2012-06-08 19:01:17Z

2

You are trying to call a PHP function via the onchange event.

You'll need to write a JavaScript function to make an AJAX call to the PHP file in order to get the result.

You can easily make the AJAX request with jQuery

$.get({
  url: "/selection.php",
  data: {
    id: "ISBN HERE"
  },
  success: function(data) {
    alert(data)
  }
})

You would also have to add something like this to the PHP file to display the result

echo selection($_GET["id"]);

The first page, which has the list of books and a Go button

<form action="page2.php" method="get">
   <!-- book selection list -->
   <input type="submit" value="Go">
</form>

The second page could list all the editions for the book with the ID $_GET[$strNameOrdinal]

To do this on the same page, with a reload, you need to check if the form has been submitted

<?php

  if (empty($_GET[$strNameOrdinal])) {
    // List Books
  } else {
    // List editions
  }

?>

edited Jun 8, 2012 at 19:01

answered Jun 8, 2012 at 18:07

user1438599

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10 Comments

Madison Scodelario Over a year ago

I hava absolutely no idea about AJAX and very little idea of JavaScript..Could you give me some more information?

user1438599 Over a year ago

I just added one to the answer

Madison Scodelario Over a year ago

can't i avoid jQuery if possible? I just want to use only javascript with php

ThiefMaster Over a year ago

@MariaKwitch: Using jQuery makes it much easier and the code cleaner. Unless you are already using another library I'd highly suggest using it. Especially since you "have absolutely no idea about AJAX and very little idea of JavaScript". It also has the advantage that any resources you'll find via google are most likely not extremely outdated and bad (which is the case for lots of plain-JS stuff in the net).

user1438599 Over a year ago

AJAX is possible without jQuery but it requires a bit more work and is not guaranteed to be compatible with all browsers.

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