I've swapped out a textbox to be a multi-select list for a front end form and changed the name of the field to an array. It basically looks like this:

<select size="10" name="options[]" multiple="multiple">
<option>Option 1</option>
<option>Option 2</option>
<option>Option 3</option>
<option>Option 4</option>
<option>Option 5</option>
</select>

My question is, which file and lines do I need to change in order to serialize my array so I can save it to a string field in my DB table?

Thank you.