Add fetch method and properties to DeclarationTVA class

Class Enhancement:
- Added missing properties: rowid, period_id, declaration_number, declaration_name, start_date, end_date, status
- Added fetch() method to retrieve declaration by ID
- Method populates object properties from database
- Returns 1 if found, 0 if not found, -1 if error

This fixes the 'Call to undefined method fetch()' error in declarationtva_view.php.

core/class/declarationtva.class.php

@@ -22,6 +22,41 @@ class DeclarationTVA
      */
     public $error;
 
+    /**
+     * @var int Declaration ID
+     */
+    public $rowid;
+
+    /**
+     * @var int Period ID
+     */
+    public $period_id;
+
+    /**
+     * @var string Declaration number
+     */
+    public $declaration_number;
+
+    /**
+     * @var string Declaration name
+     */
+    public $declaration_name;
+
+    /**
+     * @var string Start date
+     */
+    public $start_date;
+
+    /**
+     * @var string End date
+     */
+    public $end_date;
+
+    /**
+     * @var string Status
+     */
+    public $status;
+
     /**
      * Constructor
      *
@@ -34,6 +69,34 @@ class DeclarationTVA
         $this->entity = $entity;
     }
 
+    /**
+     * Fetch declaration by ID
+     *
+     * @param int $id Declaration ID
+     * @return int 1 if found, 0 if not found, -1 if error
+     */
+    public function fetch($id)
+    {
+        $sql = "SELECT * FROM " . MAIN_DB_PREFIX . "declarationtva_declarations 
+                WHERE rowid = " . (int)$id . " AND entity = " . $this->entity;
+        
+        $result = $this->db->query($sql);
+        if ($result) {
+            $obj = $this->db->fetch_object($result);
+            if ($obj) {
+                $this->rowid = $obj->rowid;
+                $this->period_id = $obj->period_id;
+                $this->declaration_number = $obj->declaration_number;
+                $this->declaration_name = $obj->declaration_name;
+                $this->start_date = $obj->start_date;
+                $this->end_date = $obj->end_date;
+                $this->status = $obj->status;
+                return 1;
+            }
+        }
+        return 0;
+    }
+
     /**
      * Create a new declaration for a period
      *