Drupal 6 to 8

Aggregator Categories

Drupal 8 no longer has the concept of aggregator categories, so they are not migrated to Drupal 8.

Allowed Protocols

Drupal 8 now stores protocols in the "filter_protocols" container parameter. If you modified the filter_allowed_protocols variable, enter it in the services.yml file.

Create Your Initial Migrations

• Create migrations using drush migrate-upgrade --configure-only as described in the section "Upgrade Using Drush".
• Ensure you have a config/sync directory that will be used in the next step.
• Export the migrations using drush config:export
• Create your own migration module.
• Copy only the YML files you want to use from the config/sync directory to the config/install directory of your new custom module, editing

The core "Migrate Drupal" module in Drupal 8 provides API support for migrating from Drupal to Drupal, and the "Migrate Drupal UI" module offers a simple user interface for upgrading from older versions of Drupal.

Dynamic queries refer to queries that are dynamically created by Drupal, rather than being supplied as an explicit query string. All insert, update, delete, and merge queries must be dynamic. Select queries can be either static or dynamic. Hence, "dynamic query" usually refers to a dynamic Select query.

The Select query builder supports using expressions in the field list. Example expressions include "double the age field," "count of all name fields," and a substring of the title field. Note that many expressions may use SQL functions, and not all SQL functions are standardized across all databases. Module developers must ensure that only expressions compatible with supported databases are used. (See List of functions and operators)

Add a Field

To add a field to a Select query, use the addField() method:

Any query can have a corresponding "count query". A count query returns the number of rows in the original query. To get a count query from an existing query (which is a select query object implementing the SelectInterface), use the countQuery() method.

Some SQL queries may return duplicate results. In such cases, duplicate rows can be filtered using the “DISTINCT” keyword in a static query. In a dynamic query, use the Different() method.