How to delete all data in one field of a particular content type?

Question

We have a content type basic page that has a Date field (field_bp_date). We want to use the hook_update to delete all data in this field. We are having trouble figuring out what is the best way to simply delete all data in the field_bp_date field on the basic page content type?

Ideally we would like to do the following:

function mymodule_update_7001(...) {
    $content_type = 'page';
    $fieldDataToDel = 'field_bp_date';

    //some function/hook to delete all the data
    ....
}

Answer 1

If you only need to do this once you could use Views Bulk Operations https://www.drupal.org/project/views_bulk_operations

/admin/structure/views

1. Click "Add new view" link
2. Show "Content" of type "YOUR_CONTENT_TYPE"
3. Click "Continue & Edit" button

Under the FORMAT section change Show: click 'Content' change to 'Fields'

1. Click 'Apply' button
2. Click 'Apply' button again

Under FIELDS section click the 'Add' button

1. Checkmark 'Bulk operations: Content'
2. Under SELECTED BULK OPERATIONS choose 'Modify entity values' checkbox
3. Scroll down a little, you will see OPERATION SETTINGS choose that date Field you want to edit.
4. Click 'Apply' button
5. Click 'Save' to save that View

Go to the View Page you just created.

1. Under Operations choose 'Modify entity values'
2. Select one or all of them (I suggest you do one as a test).
3. Click the 'Execute' button. This page will allow you to set the Date to anything you want, even nothing. TIP! for Date if you want no date you need to change all values to blank. You can't delete just the hours, you need to set all of them to blank, which gives you the result you requested.
4. Click the 'Next' button.
5. Click the 'Confirm' Button.

Congrats. Go back and run it on all of them, if it went as expected on the one test node.

Answer 2

You can just run a mysql delete command. As this is a date field, there aren't any dependencies on other tables.

function mymodule_update_7001() {
  db_query("DELETE FROM field_data_field_bp_date WHERE entity_type = 'node' and bundle = 'page'");
  db_query("DELETE FROM field_revision_field_bp_date WHERE entity_type = 'node' and bundle = 'page'");
}

Note: You would only want to use this approach if you felt certain that there weren't any other modules that needed to react to that data.