Certain DC fields are required?

Can you set it so that certain tags (such as title) are required in order to save a record? I want to make some fields a required field and you cannot save the record until that field has data. Is that possible?

That would call for a plugin that uses the before_save_item hook.

It might work something like this:

class RequiredMetadataPlugin extends Omeka_Plugin_AbstractPlugin
{
    protected $_hooks = array('before_save_item');

    public function hookBeforeSaveItem($args)
    {
        $item = $args['record'];
        $title = metadata($item, array('Dublin Core', 'Title'));
        if(empty($title)) {
            $item->addError("DC Title", 'DC Title cannot be empty!');
        }
    }
}

Make a directory in plugins called RequiredMetadata, and add this as a file called RequiredMetadataPlugin.php

For the fields you need to require, follow the pattern here for titles.

I might've missed some details, but this'll get us close.

Thank you! That worked for me. Now if I wanted to advance it further, is there a way on the Item Type Metadata to ask if the tag is required (like is HTML) when a new tag is created and then add that to the RequiredMetadataPlugin? Does that make sense?

What I've written doesn't interact with the element forms, though that might be possible with one or more of the filters. (Notice that this solution also doesn't tell the user what elements are required, which could also happen via the filters).

It would take using the various Element filters in this list.