When migrating a site, it's important to catch all the url aliases and redirects. Otherwise, existing links on the web may not work and search rankings will drop.
URL Alias
The d7_url_alias source plugin fetches data from the url_alias table and provides pid, source, alias, and language properties.
The migration needs to get the entity id from the source (node/123) and use it in a migration lookup.
Here is a hook_migrate_prepare_row() function for extracting the necessary properties.
function my_module_migrate_prepare_row(\Drupal\migrate\Row $row, \Drupal\migrate\Plugin\MigrateSourceInterface $source, \Drupal\migrate\Plugin\MigrationInterface $migration) {
if ($migration->id() == 'upgrade_d7_url_alias') {
$source = $row->getSourceProperty('source');
$source_parts = explode('/', $source);
$source_id = array_pop($source_parts);
$source_path = implode('/', $source_parts);
$source_type = str_replace('/', '_', $source_path);
$row->setSourceProperty('source_id', $source_id);
$row->setSourceProperty('source_type', $source_type);
$row->setSourceProperty('source_path', $source_path);
}
}This sets source_id, source_type, and source_path properties.
Here's a migration that uses the properties to convert the source path.
source:
plugin: d7_url_alias
constants:
slash: /
process:
_dest_id:
-
plugin: skip_on_value
value:
- node
not_equals: true
method: row
source: source_type
-
plugin: migration_lookup
source: source_id
migration:
- upgrade_d7_node_blog
- upgrade_d7_node_event
- upgrade_d7_node_page
path:
plugin: concat
source:
- source
- '@_dest_id'
alias:
-
plugin: concat
source:
- constants/slash
- alias
langcode:
-
plugin: get
source: languageModules