I need to convert a field on a paragraph from the string_long type to the text_long type.

There is data in the field so I can't change it in the UI.

How would I do this programmatically?


2 Answers 2


Here's the solution I came up with based on the example code provided by https://drupal.stackexchange.com/users/71454/miststudent2011. I had to adapt it a bit for this specific case:

 * Convert plain text field to formatted text field.
function mymodule_update_9002() {
  $entity_type = 'paragraph';
  $field = 'field_paragraph_variant';

  // Retrieve existing field data.
  $database = \Drupal::database();
  $tables = [
  $existing_data = [];
  foreach ($tables as $table) {
    // Get the old data.
    $existing_data[$table] = $database->select($table)

  // Get the field config.
  $field_storage = \Drupal::entityTypeManager()->getStorage('field_storage_config');
  $field_storage_config = $field_storage->loadByProperties(['field_name' => $field]);

  foreach ($field_storage_config as $field_storage) {
    // Save the config as an array and change the type.
    $new_field_storage = $field_storage->toArray();
    $new_field_storage['type'] = 'text_long';

    // Delete the original field, otherwise the new table columns won't get added.

    // Re-create the field.
    $new_field_storage = $field_storage->create($new_field_storage);

  // Restore the data.
  foreach ($tables as $table) {
    $insert_query = $database
        $field . '_value',
        $field . '_format',
    foreach ($existing_data[$table] as $row) {
      $row[$field . '_format'] = 'subscriber_text';

There is now a module for that: https://www.drupal.org/project/field_type_converter

As mentioned in the module page, you can implement a hook_post_update_NAME with this code to convert the field_foo in nodes into a long_text.

function hook_post_update_NAME(&$sandbox) {
  $field_map['node'] = [
    'field_foo' => 'text_long',
  return \Drupal\field_type_converter\FieldTypeConverter::processBatch($sandbox, $field_map);

Don't forget to run drush updated in order to execute this conversion.

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