feat: Add run_in_transaction decorator.

src/viur/core/decorators.py

@@ -133,3 +133,20 @@ def decorator(func):
         return decorator
 
     return decorator(func)
+
+
+def run_in_transaction(func: Callable) -> Method:
+    """
+    Decorator, which enforces the Method to run in a transaction.
+    .. code-block:: python
+        from viur.core.decorators import run_in_transaction
+        def outer_method(key)
+            @run_in_transaction
+            def transaction_method(key):
+                db.Get(key)
+            return transaction_method(key)
+    """
+
+    func = Method.ensure(func)
+    func.run_in_transaction = True
+    return func

src/viur/core/module.py

@@ -35,6 +35,7 @@ def __init__(self, func: typing.Callable):
         self.ssl = False
         self.methods = ("GET", "POST", "HEAD")
         self.seo_language_map = None
+        self.run_in_transaction = False
 
         # Inspection
         self.signature = inspect.signature(self._func)
@@ -282,6 +283,8 @@ def parse_value_by_annotation(annotation: type, name: str, value: str | list | t
                 raise errors.Forbidden(self.access["message"]) if self.access["message"] else errors.Forbidden()
 
         # call with instance when provided
+        if self.run_in_transaction:
+            return db.RunInTransaction(self._func, *args, **kwargs)
         if self._instance:
             return self._func(self._instance, *args, **kwargs)