I have created a custom fieldtype that uses a multiselect box. However when I save the entry in the CMS, the following error occurs

A Database Error Occurred
Error Number: 1054

Unknown column 'Array' in 'field list'

UPDATE `exp_channel_data` SET `channel_id` = '27', `field_id_108` = Array, `field_id_109`...

Any suggestions? I have checked the Multiselect fieldtype within EE and my code looks OK (I think)

1 Answer 1


Since you're using a multiselect element, you're posting an array of data when the entry is saved. But you can't simply insert an array into the database - you need to turn it into a string.

So in your fieldtype's save() method, you need to do something like:

return implode('|', $data);


return json_encode($data);

Then you need to turn your data back into an array in replace_tag() and display_field().

$data = explode('|', $data);


$data = json_decode($data);

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