diff --git a/src/Adapter/DefaultAdapterTrait.php b/src/Adapter/DefaultAdapterTrait.php
index 9c4cf8b..1d9f75b 100644
--- a/src/Adapter/DefaultAdapterTrait.php
+++ b/src/Adapter/DefaultAdapterTrait.php
@@ -104,7 +104,7 @@ trait DefaultAdapterTrait
     public function generateAlterColumn(FieldDefinition $definition, array $field) : string|\Stringable
     {
         if ($field['previous']) {
-            $position = sprintf('AFTER %s', $adapter->escapeIdentifier($field['previous']['field'], AdapterInterface::IDENTIFIER_FIELD));
+            $position = sprintf('AFTER %s', $this->escapeIdentifier($field['previous']['field'], AdapterInterface::IDENTIFIER_FIELD));
         }
         else {
             $position = "FIRST";
diff --git a/src/Attribute/Attribute.php b/src/Attribute/Attribute.php
index 348792b..7072de4 100644
--- a/src/Attribute/Attribute.php
+++ b/src/Attribute/Attribute.php
@@ -3,13 +3,20 @@
 namespace Ulmus\Attribute;
 
 use Ulmus\Common\EntityField;
+use Ulmus\Repository;
 
 class Attribute
 {
-    public static function handleArrayField(null|\Stringable|string|array $field) : mixed
+    public static function handleArrayField(null|\Stringable|string|array $field, null|string|bool $alias = Repository::DEFAULT_ALIAS, string $separator = ', ') : mixed
     {
         if ( is_array($field) ) {
             $class = array_shift($field);
+            $field[1] ??= $alias;
+
+            if (is_array($field[0])) {
+                $field[] = $separator;
+                return $class::fields(...$field);
+            }
 
             return $class::field(...$field);
         }
diff --git a/src/Attribute/Property/Field/ForeignKey.php b/src/Attribute/Property/Field/ForeignKey.php
index a2098a8..252fdd4 100644
--- a/src/Attribute/Property/Field/ForeignKey.php
+++ b/src/Attribute/Property/Field/ForeignKey.php
@@ -10,6 +10,17 @@ use Ulmus\Attribute\Attribute;
  */
 #[\Attribute(\Attribute::TARGET_PROPERTY)]
 class ForeignKey extends PrimaryKey {
+
+    public const SET_NULL = "null";
+
+    public const SET_DEFAULT = "default";
+
+    public const RESTRICT = "restrict";
+
+    public const NO_ACTION = "noaction";
+
+    public const CASCADE = "cascade";
+
     public function __construct(
         public ? string $name = null,
         public ? string $type = 'bigint',
@@ -22,8 +33,11 @@ class ForeignKey extends PrimaryKey {
         public bool $nullable = false,
         public mixed $default = null,
         public bool $readonly = false,
+        public null|array|string|\Stringable $foreignKey = "",
         public null|array|string|\Stringable $references = null,
+        public null|string $onDelete = self::NO_ACTION,
+        public null|string $onUpdate = self::NO_ACTION,
     ) {
-        $this->references = Attribute::handleArrayField($this->references);
+        $this->references = Attribute::handleArrayField($this->references, false);
     }
 }
diff --git a/src/Attribute/Property/Index.php b/src/Attribute/Property/Index.php
new file mode 100644
index 0000000..70e6311
--- /dev/null
+++ b/src/Attribute/Property/Index.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace Ulmus\Attribute\Property;
+
+#[\Attribute(\Attribute::TARGET_PROPERTY)]
+class Index {
+
+    public const TYPE_PRIMARY = 'primary';
+
+    public const TYPE_INDEX = 'index';
+
+    public const TYPE_UNIQUE = 'unique';
+
+    public const TYPE_SPATIAL = 'spatial';
+
+    public const TYPE_FULLTEXT = 'fulltext';
+
+    public function __construct(
+        public string $type = self::TYPE_INDEX,
+    ) {}
+}
diff --git a/src/EntityCollection.php b/src/EntityCollection.php
index 7c6216e..e6d4914 100644
--- a/src/EntityCollection.php
+++ b/src/EntityCollection.php
@@ -4,7 +4,7 @@ namespace Ulmus;
 
 use Generator;
 
-class EntityCollection extends \ArrayObject {
+class EntityCollection extends \ArrayObject implements \JsonSerializable {
 
     public ? string $entityClass = null;
 
@@ -340,6 +340,11 @@ class EntityCollection extends \ArrayObject {
         return ( new $className() )->fromArray($dataset);
     }
 
+    public function jsonSerialize(): mixed
+    {
+        return $this->toArray();
+    }
+
     public function append($value) : void
     {
         if ( is_array($value) ) {
diff --git a/src/EntityTrait.php b/src/EntityTrait.php
index c94f77b..bf2af7e 100644
--- a/src/EntityTrait.php
+++ b/src/EntityTrait.php
@@ -301,15 +301,15 @@ trait EntityTrait {
     }
 
     #[Ignore]
-    public static function field($name, ? string $alias = Repository::DEFAULT_ALIAS) : EntityField
+    public static function field($name, null|string|bool $alias = Repository::DEFAULT_ALIAS) : EntityField
     {
-        return new EntityField(static::class, $name, $alias ? Ulmus::repository(static::class)->adapter->adapter()->escapeIdentifier($alias, Adapter\AdapterInterface::IDENTIFIER_FIELD) : Repository::DEFAULT_ALIAS, Ulmus::resolveEntity(static::class));
+        return new EntityField(static::class, $name, $alias ? Ulmus::repository(static::class)->adapter->adapter()->escapeIdentifier($alias, Adapter\AdapterInterface::IDENTIFIER_FIELD) : ( $alias === false ? '' : Repository::DEFAULT_ALIAS ), Ulmus::resolveEntity(static::class));
     }
 
     #[Ignore]
-    public static function fields(array $fields, ? string $alias = Repository::DEFAULT_ALIAS) : string
+    public static function fields(array $fields, null|string|bool $alias = Repository::DEFAULT_ALIAS, string $separator = ', ') : string
     {
-        return implode(', ', array_map(function($item) use ($alias){
+        return implode($separator, array_map(function($item) use ($alias){
             return static::field($item, $alias);
         }, $fields));
     }