Fix ReadTransaction (#48)

Author: davidbrochart

python/pycrdt/array.py

@@ -206,7 +206,11 @@ def observe_callback(callback: Callable[[Any], None], doc: Doc, event: Any):
 def observe_deep_callback(callback: Callable[[Any], None], doc: Doc, events: list[Any]):
     for idx, event in enumerate(events):
         events[idx] = event_types[type(event)](event, doc)
+        if idx == 0:
+            _event = event
+    doc._txn = ReadTransaction(doc=doc, _txn=_event.transaction)
     callback(events)
+    doc._txn = None
 
 
 class ArrayEvent(BaseEvent):

python/pycrdt/map.py

@@ -160,7 +160,11 @@ def observe_callback(callback: Callable[[Any], None], doc: Doc, event: Any):
 def observe_deep_callback(callback: Callable[[Any], None], doc: Doc, events: list[Any]):
     for idx, event in enumerate(events):
         events[idx] = event_types[type(event)](event, doc)
+        if idx == 0:
+            _event = event
+    doc._txn = ReadTransaction(doc=doc, _txn=_event.transaction)
     callback(events)
+    doc._txn = None
 
 
 class MapEvent(BaseEvent):

python/pycrdt/transaction.py

@@ -35,7 +35,7 @@ def __exit__(
         self._nb -= 1
         # only drop the transaction when exiting root context manager
         # since nested transactions reuse the root transaction
-        if self._nb == 0:
+        if self._nb == 0 and not isinstance(self, ReadTransaction):
             # dropping the transaction will commit, no need to do it
             # self._txn.commit()
             assert self._txn is not None