Thanks for your question and for your patience while I was traveling.
Populating the “Caption” field is actually done by WordPress, not MLA, in most cases. You can find the relevant code in the wp_read_image_metadata() function contained in the /wp-admin/includes/image.php file.
I believe you can override this WordPress “help” by creating your own IPTC/EXIF mapping rule:
- Go to the Settings/Media Library Assistant IPTC/EXIF tab.
- If you want to apply the rule to new items as they are uploaded, check the “Enable IPTC/EXIF Mapping when adding new media” and “Enable IPTC/EXIF Mapping when updating media metadata” boxes.
- Click the “Standard” view to filter the display to the six standard fields.
- Locate the “Caption” rule entry and click the “Edit” rollover action.
- In the “IPTC Value” dropdown control leave the default “- None (select a value) -” in place.
- In the “EXIF/Template Value” text box enter “template:[+empty+]”.
- In the “Priority” dropdown, select “EXIF”.
- In the “Existing Text” dropdown, select “Replace”. This will apply the update to all of the existing caption values. Be careful when applying this to your existing items.
- Scroll down to the bottom of the screen and click “Save Changes”.
Once you define a rule you can apply it to a single item, multiple items or all items:
- To map a single item, go to the Media/Assistant submenu and click the thumbnail of the item you want (or click the “Edit” rollover action) to get the Media/Edit Media screen. You can click the “Map IPTC/EXIF metadata” link to run your rules on this item, then scroll down and look at the “Uploaded on” value in the “Save” meta box to inspect the results.
- To map two or more items, go to the Media/Assistant submenu and click the checkbox next to the items you want. Then, select “Edit” from the “Bulk Actions” dropdown above the checkboxes and click “Apply” to open the Bulk Edit area. Click the “Map IPTC/EXIF metadata” button to run your rules on the selected items.
- To map all of your items, stay on the Settings/Media Library Assistant IPTC/EXIF tab and click the “Execute” rollover action for the Uploaded on rule. This may take a while.
- The Settings/Media Library Assistant IPTC/EXIF tab also has an “Execute” Bulk Action you can use to apply several rules at once, and an “Execute All Rules” button to run all of the rules against all of your items.
You can also use MLA’s Bulk Edit area on the Media/Assistant admin submenu to be more selective in applying this update to existing items. I will respond to your related topic (Batch empty value in Bulk Edit) with more information.
I am marking this topic resolved, but please update it if you have problems or further questions regarding the above suggestions. Thanks for your interest in the plugin.
