External content migration translation problem

Question

I am trying to import content into Drupal 8 from an external source (not previous Drupal version). I have crawled the original site and placed the content in a database. I am then writing a custom module to bring it into Druapl. I have the default language as English so when I run the migration for the English content there has no issue. It all imports perfectly. When I then run the translation migration, with French content, I get this error:

 [error]  SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'name' cannot be null: INSERT INTO {key_value} (name, collection, value) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2); Array
(
    [:db_insert_placeholder_0] =>
    [:db_insert_placeholder_1] => node_translation_redirect
    [:db_insert_placeholder_2] => a:2:{i:0;N;i:1;N;}
)

Despite the error the content is imported, but as separate nodes instead of as translations to the original migration. I am using drush to run the migrations. Even though the French is imported, incorrectly, drush reports that the migration failed. I try to rollback both and the French does not get removed. I have to remove it manually.

I searched around but have not been able to find anyone having issues with SQL migrations.

Any help is appreciated. Thanks.

Here are my files:

mymigrate_content.yml

id: mymigrate_content
label: my content migration
langcode: en
source:
  plugin: mymigrate_content
  default_lang: true
  key: canada
  ids:
    pageid:
      type: integer
process:
  id: pageid
  title: title
  'body/value': body
  'body/format':
    plugin: default_value
    default_value: full_html
  'moderation_state/target_id':
    plugin: default_value
    default_value: published
destination:
  plugin: 'entity:node'
  default_bundle: page
  langcode: en
  no_stub: true

mymigrate_content_translation.yml

id: mymigrate_content_translation
label: my content migration
langcode: fr
source:
  plugin: mymigrate_content_translation
  translations: true
  default_lang: false
  key: canada
  ids:
    pageid:
      type: integer
process:
  id: 
    plugin: migration_lookup
    migration: mymigrate_content
    source: pageid
  title: title
  'body/value': body
  'body/format':
    plugin: default_value
    default_value: full_html
  'moderation_state/target_id':
    plugin: default_value
    default_value: published
  content_translation_source:
    plugin: default_value
    default_value: "en"
destination:
  plugin: 'entity:node'
  default_bundle: page
  langcode: fr
  no_stub: true
  translations: true

MyMigrate.php

<?php
namespace Drupal\ca_migrate\Plugin\migrate\source;

use Drupal\migrate\Plugin\migrate\source\SqlBase;
use Drupal\migrate\Row;

/**
 * Migration
 * 
 * @MigrateSource(
 *  id = "mymigrate_content",
 * source_module = "mymigrate",
 * )
 */
class MyMigrate extends SqlBase {
  /**
   * @var integer $rowCount
   */
  public $rowCount = -1;

  /**
   * {@inheritdoc}
   */
  public function query() {
    $query = $this->select('pagecontent', 'pc')
      ->condition('pc.language', 'en', '=')
      ->fields('pc', [
        'pageid',
        'language',
        'body',
        'originalurlpath',
        'title',
      ]);

    return $query;
  }


  /**
   * {@inheritdoc}
   */
  public function fields() {
    $fields = [
      'pageid' => $this->t('pageid'),
      'language' => $this->t('language'),
      'body' => $this->t('body'),
      'originalurlpath' => $this->t('originalurlpath'),
      'title' => $this->t('title'),
    ];

    return $fields;
  }

  /**
   * {@inheritdoc}
   */
  public function getIds() {
    return [
      'pageid' => [
        'type' => 'integer',
        'alias' => 'pc',
      ],
    ];
  }
}

MyMigrateFr.php

<?php
namespace Drupal\ca_migrate\Plugin\migrate\source;

use Drupal\migrate\Plugin\migrate\source\SqlBase;
use Drupal\migrate\Row;

/**
 * Migration
 * 
 * @MigrateSource(
 *  id = "mymigrate_content_translation",
 * source_module = "mymigrate",
 * )
 */
class MyMigrateFr extends SqlBase {
  /**
   * @var integer $rowCount
   */
  public $rowCount = -1;

  /**
   * {@inheritdoc}
   */
  public function query() {
    $query = $this->select('pagecontent', 'pc')
      ->condition('pc.language', 'fr', '=')
      ->fields('pc', [
        'pageid',
        'language',
        'body',
        'originalurlpath',
        'title',
      ]);

    return $query;
  }


  /**
   * {@inheritdoc}
   */
  public function fields() {
    $fields = [
      'pageid' => $this->t('pageid'),
      'language' => $this->t('language'),
      'body' => $this->t('body'),
      'originalurlpath' => $this->t('originalurlpath'),
      'title' => $this->t('title'),
    ];

    return $fields;
  }

  /**
   * {@inheritdoc}
   */
  public function getIds() {
    return [
      'pageid' => [
        'type' => 'integer',
        'alias' => 'pc',
      ],
    ];
  }
}

Answer 1

I was finally able to trace the problem. The migration code was expecting a value for the key nid. I was able to provide the appropriate value by overriding the function prepareRow.

Here is the code I used in both MyMigrate.php and MyMigrateFr.php:

  /**
   * {@inheritdoc}
   */
  public function prepareRow(Row $row) {
    $nid = $row->getSourceProperty('pageid');
    $row->setSourceProperty('nid', $nid);
    $row->setDestinationProperty('nid', $nid);

    return parent::prepareRow($row);
  }

Answer 2

I encountered the same problem migrating from a JSON source:

Integrity constraint violation: 1048 Column 'name' cannot be null: INSERT INTO {key_value} (name, collection, value) ...

with empty value for 'name'.

I solved the problem by removing the line

  translations: true

from the source: block. I think this is only needed in the destination: block.