symphonycms: Cannot delete content from "optional" fields

Apologies in advance if this has already been addressed, however, the behaviour is still present in the 2.7.x branch and I’ve not located a fix or existing issue. Appears this bug has been around since 18th of May.

Affected Symphony version(s) : Since PR #2664

This relates to code in EntryManager line 119 (https://github.com/symphonycms/symphony-2/blob/2.7.x/symphony/lib/toolkit/class.entrymanager.php#L119)

Expected Behaviour

If there is a field flagged as optional, editing it to have an empty value should cause anything that was there to be deleted.

Current Behaviour

The original value persists.

Steps to reproduce

1. Create a new section.
2. Add a text input field to that section and set it to optional
3. Create a new entry in that section, ensuring to add a value to the text input. e.g. “APPLE”
4. Go back to the entry to edit it. Delete the value “APPLE” from the text input field, then save the entry.
5. Observe the value “APPLE” persists.

Reason

When an entry is saved, field data is passed through this method. For an optional field with no value, the data looks something like this:

int(113)
array(0) {
}

This code is executed near the top of EntryManager::saveFieldData():

        // Check if we have field data
        if (!is_array($field) || empty($field)) {
            return;
        }

When this code is executed, it will skip over fields with an empty value. Consider the previous code https://github.com/symphonycms/symphony-2/blob/0dd2c1238a62aa620d7f7e5737843380a31c8b6a/symphony/lib/toolkit/class.entrymanager.php#L186

Note that a call to Symphony::Database()->delete(...) is triggered first. This allows the desired behaviour to occur. i.e. removing a value from an optional field.

Solution

Delete field data before checking for an empty state.