diff -u b/core/modules/migrate/src/Plugin/migrate/source/SqlBase.php b/core/modules/migrate/src/Plugin/migrate/source/SqlBase.php
--- b/core/modules/migrate/src/Plugin/migrate/source/SqlBase.php
+++ b/core/modules/migrate/src/Plugin/migrate/source/SqlBase.php
@@ -8,9 +8,12 @@
 namespace Drupal\migrate\Plugin\migrate\source;
 
 use Drupal\Core\Database\Database;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\State\StateInterface;
 use Drupal\migrate\Entity\MigrationInterface;
 use Drupal\migrate\Plugin\migrate\id_map\Sql;
 use Drupal\migrate\Plugin\MigrateIdMapInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
  * Sources whose data may be fetched via DBTNG.
@@ -21,7 +24,7 @@
  * is present, it is used as a database connection information array to define
  * the connection.
  */
-abstract class SqlBase extends SourcePluginBase {
+abstract class SqlBase extends SourcePluginBase implements ContainerFactoryPluginInterface {
 
   /**
    * @var \Drupal\Core\Database\Query\SelectInterface
@@ -34,10 +37,31 @@
   protected $database;
 
   /**
+   * State service for retrieving database info.
+   *
+   * @var \Drupal\Core\State\StateInterface
+   */
+  protected $state;
+
+  /**
    * {@inheritdoc}
    */
-  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration) {
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, StateInterface $state) {
     parent::__construct($configuration, $plugin_id, $plugin_definition, $migration);
+    $this->state = $state;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $migration,
+      \Drupal::state()
+    );
   }
 
   /**
@@ -61,47 +85,44 @@
       // See if the database info is in state - if not, fallback to
       // configuration.
       if (isset($this->configuration['database_state_key'])) {
-        // @todo: Inject the state service.
-        $database_state = \Drupal::state()->get($this->configuration['database_state_key']);
-        if (isset($database_state['target'])) {
-          $target = $database_state['target'];
-        }
-        else {
-          $target = 'default';
-        }
-        if (isset($database_state['key'])) {
-          $key = $database_state['key'];
-        }
-        else {
-          $key = 'migrate';
-        }
-        if (isset($database_state['database'])) {
-          Database::addConnectionInfo($key, $target, $database_state['database']);
-        }
+        $this->database = $this->setUpDatabase($this->state->get($this->configuration['database_state_key']));
       }
       else {
-        if (isset($this->configuration['target'])) {
-          $target = $this->configuration['target'];
-        }
-        else {
-          $target = 'default';
-        }
-        if (isset($this->configuration['key'])) {
-          $key = $this->configuration['key'];
-        }
-        else {
-          $key = 'migrate';
-        }
-        if (isset($this->configuration['database'])) {
-          Database::addConnectionInfo($key, $target, $this->configuration['database']);
-        }
+        $this->database = $this->setUpDatabase($this->configuration);
       }
-      $this->database = Database::getConnection($target, $key);
     }
     return $this->database;
   }
 
   /**
+   * Get a connection to the referenced database, adding the connection if
+   * necessary.
+   *
+   * @param $database_info
+   *
+   * @return \Drupal\Core\Database\Connection
+   *   The connection to use for this plugin's queries.
+   */
+  protected function setUpDatabase($database_info) {
+    if (isset($database_info['target'])) {
+      $target = $database_info['target'];
+    }
+    else {
+      $target = 'default';
+    }
+    if (isset($database_info['key'])) {
+      $key = $database_info['key'];
+    }
+    else {
+      $key = 'migrate';
+    }
+    if (isset($database_info['database'])) {
+      Database::addConnectionInfo($key, $target, $database_info['database']);
+    }
+    return Database::getConnection($target, $key);
+  }
+
+  /**
    * Wrapper for database select.
    */
   protected function select($table, $alias = NULL, array $options = array()) {
diff -u b/core/modules/migrate/src/Tests/SqlBaseTest.php b/core/modules/migrate/src/Tests/SqlBaseTest.php
--- b/core/modules/migrate/src/Tests/SqlBaseTest.php
+++ b/core/modules/migrate/src/Tests/SqlBaseTest.php
@@ -97,7 +97,9 @@
   /**
    * Override the constructor so we can create one easily.
    */
-  public function __construct() {}
+  public function __construct() {
+    $this->state = \Drupal::state();
+  }
 
   /**
    * Get the database without caching it.
only in patch2:
unchanged:
--- a/core/modules/migrate/tests/src/Unit/MigrateSqlSourceTestCase.php
+++ b/core/modules/migrate/tests/src/Unit/MigrateSqlSourceTestCase.php
@@ -77,6 +77,7 @@
    */
   protected function setUp() {
     $module_handler = $this->getMock('Drupal\Core\Extension\ModuleHandlerInterface');
+    $state = $this->getMock('Drupal\Core\State\StateInterface');
     $entity_manager = $this->getMock('Drupal\Core\Entity\EntityManagerInterface');
 
     $migration = $this->getMigration();
@@ -86,7 +87,7 @@ protected function setUp() {
 
     // Setup the plugin.
     $plugin_class = static::PLUGIN_CLASS;
-    $plugin = new $plugin_class($this->migrationConfiguration['source'], $this->migrationConfiguration['source']['plugin'], array(), $migration, $entity_manager);
+    $plugin = new $plugin_class($this->migrationConfiguration['source'], $this->migrationConfiguration['source']['plugin'], array(), $migration, $state, $entity_manager);
 
     // Do some reflection to set the database and moduleHandler.
     $plugin_reflection = new \ReflectionClass($plugin);
only in patch2:
unchanged:
--- a/core/modules/migrate_drupal/src/Plugin/migrate/source/DrupalSqlBase.php
+++ b/core/modules/migrate_drupal/src/Plugin/migrate/source/DrupalSqlBase.php
@@ -11,6 +11,7 @@
 use Drupal\Core\Entity\DependencyTrait;
 use Drupal\Core\Entity\EntityManagerInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\State\StateInterface;
 use Drupal\migrate\Entity\MigrationInterface;
 use Drupal\migrate\Exception\RequirementsException;
 use Drupal\migrate\Plugin\migrate\source\SqlBase;
@@ -51,8 +52,8 @@
   /**
    * {@inheritdoc}
    */
-  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, EntityManagerInterface $entity_manager) {
-    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration);
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, StateInterface $state, EntityManagerInterface $entity_manager) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration, $state);
     $this->entityManager = $entity_manager;
   }
 
@@ -89,6 +90,7 @@ public static function create(ContainerInterface $container, array $configuratio
       $plugin_id,
       $plugin_definition,
       $migration,
+      \Drupal::state(),
       $container->get('entity.manager')
     );
   }
only in patch2:
unchanged:
--- a/core/modules/migrate_drupal/src/Plugin/migrate/source/Variable.php
+++ b/core/modules/migrate_drupal/src/Plugin/migrate/source/Variable.php
@@ -8,6 +8,7 @@
 namespace Drupal\migrate_drupal\Plugin\migrate\source;
 
 use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\State\StateInterface;
 use Drupal\migrate\Entity\MigrationInterface;
 
 /**
@@ -32,8 +33,8 @@ class Variable extends DrupalSqlBase {
   /**
    * {@inheritdoc}
    */
-  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, EntityManagerInterface $entity_manager) {
-    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration, $entity_manager);
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, StateInterface $state, EntityManagerInterface $entity_manager) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $migration, $state, $entity_manager);
     $this->variables = $this->configuration['variables'];
   }
 
only in patch2:
unchanged:
--- a/core/modules/migrate_drupal/tests/src/Unit/source/d6/Drupal6SqlBaseTest.php
+++ b/core/modules/migrate_drupal/tests/src/Unit/source/d6/Drupal6SqlBaseTest.php
@@ -68,8 +68,9 @@ class Drupal6SqlBaseTest extends MigrateTestCase {
    */
   protected function setUp() {
     $plugin = 'placeholder_id';
+    $state = $this->getmock('Drupal\Core\State\StateInterface');
     $entity_manager = $this->getmock('Drupal\Core\Entity\EntityManagerInterface');
-    $this->base = new TestDrupal6SqlBase($this->migrationConfiguration, $plugin, array(), $this->getMigration(), $entity_manager);
+    $this->base = new TestDrupal6SqlBase($this->migrationConfiguration, $plugin, array(), $this->getMigration(), $state, $entity_manager);
     $this->base->setDatabase($this->getDatabase($this->databaseContents));
   }