Updating just a single content field from a plugin I have a Task that is running through a collection of elements, moving some data from one field to another. The problem I am hitting (more and more with situations like this) is that in order to update just one field of an element, using the recommended BaseElementModel::setContentFromPost() method, I have to also account for all kinds of other values to get it to validate and save.

I know you need to specify the IDs (from questions like these two) for any relation fields that are required, which is not ideal, but not a huge issue in this case.

However, on this project I also have the Venti plugin installed, with its Venti_EventFieldType for dates and RRULEs, and I'm having to manually pass through a big array of any existing start/end date information into setContentFromPost() just so the validation for that field will pass, even though I'm doing absolutely nothing with that field.

Is there not a single way to update a single field's value, without already knowing the way data needs to be formatted for any other fields that might be on that ContentModel? Otherwise I don't see how a general-release plugin could be made that can modify existing elements, without knowing about the setContentFromPost()-specific data format of every possible Field Type in advance.
I don't have much experience using tasks, but I often write plugin methods to move data around. Typically, I just use the EntriesService saveEntry or RelationService saveRelation as needed.

Here is a sample from a recent data move:

    // Assign category and save entries
    foreach($unassignedEntries as $entry) {

        $success = craft()-&gt;relations-&gt;saveRelations($field, $entry, array($categoryId));

        if (!$success) {
            LogicPlugin::log('Couldn’t update entry "'.$entry-&gt;title.'"', LogLevel::Error);
        }
        else {
            LogicPlugin::log('Successfully updated entry "'.$entry-&gt;title.'"', LogLevel::Info);
        }
    }