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May

Variable Variables and Template Lite

Posted by tarnus  Published in PHP, Template Lite

There is one programing concept that always hurts my head, and that is the variable variables or dynamic variables. What dynamic let you do is access data from the value of the a variable you are viewing. (See I told you it would hurt your head)

 
$b =20;  // set the value of b
$c="b";  // set c to the name of the variable you want to view
$d=${$c}; // the variable variable  $d is now equal to 20
 

Many of you are probably asking yourself, " OK I understand that , but why do I need to do that?"
The number one place I use this, is in a web grid form. Any place you need to update/or delete data in that grid. Below is an example of what a grid of data may look like:

Data Grid

The issues you face in the above grid is how do I delete multiple items and change multiple elements of data in grid once it is submitted. The solution is you assign each field a row number and add that to the field name.

Example:

 
<input name="del_1" type="checkbox" />
<input name="id_1" type="hidden" value="117" />
<input name="del_2" type="checkbox" />
<input name="id_2" type="hidden" value="95" />

Note each field had its name attached with a _row number so you will see an id_1 as a field name. After this form is submitted you can use the below php code to get the values dynamically.


// Check for item delete
if ((isset($_POST['delete'])) or (isset($_POST['delete_x']))){
for ($i=0; $i<=$totrecs; $i++)
{
$tdel=$_POST['del_'.$i];
$tid=$_POST['id_'.$i];
// Another way to do this is this way
// $tempvar="id_".$i;
// $tid=$_POST[${$tempvar}];
if ($tdel=="on")
{
// Delete Item, the item ID is $tid
}
} // Loop
} // End Post Check

Template Lite And Dynamic Variables
Form Data grid is also the reason I used dynamic variables in templates. Once I have edited a data grid I need to set values in the grid, select drop downs and, check radio or check boxes. There is some extra steps you need to do to use them and it also depends on how you pass your data to template lite. The following is an example showing a more complex use of variable variables.

{foreach key=key2 value=item2 from=$jetarray }
{ assign var="dummyvar1" value="`$item2.jetski_id`_bookid"}
{ assign var="dummyvar2" value="`$item2.jetski_id`_owner"}
{ assign var="cellcolor" value="`$item2.jetski_id`_color"}
{ assign var="dummyvar3" value="`$item2.jetski_id`"}
 
 {if $item[$dummyvar1]!=""}
   {if $session.myid == $item[$dummyvar2]}
<input name="jetid_{$item2.jetski_id}_{$key}" type="hidden"
 value="{$item2.jetski_id}" />
   {/if}
{/if}
 
 {/foreach}

Note we assigned a variable $dummyvar1 with the value $item2.jetski_id and appended _bookid to that variable name. Jetski number 1 turns into 1_bookid. After that we pull the value out of the array $item[$dummyvar1] so what we are actually doing is viewing $item['1_bookid'].

While there are some other uses for dynamic variables these are how I most recently have used them. If it helps someone other than myself, cool. Otherwise this is a place I have my own personal reference library.


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