Reuse transaction objects when doing tm.begin() so old objects that…

… reference

  old transaction object will still work and not be orphaned.

CHANGELOG.rst

@@ -1,6 +1,10 @@
 1.0.0a6 (unreleased)
 --------------------
 
+- Reuse transaction objects when doing `tm.begin()` so old objects that reference
+  old transaction object will still work and not be orphaned.
+  [vangheem]
+
 - Fix container objects not having current transaction when new objects are
   registered for them
   [vangheem]

guillotina/db/transaction.py

@@ -30,6 +30,11 @@ class Status:
 class Transaction(object):
 
     def __init__(self, manager, request=None):
+        # so we can reuse the same transaction object
+        self.init(manager, request)
+
+    def init(self, manager, request=None):
+        # so you can re-initialize a transaction object
         self._txn_time = None
         self._tid = None
         self.status = Status.ACTIVE

guillotina/db/transaction_manager.py

@@ -42,8 +42,10 @@ async def begin(self, request=None):
                 self._pool = LifoQueue()
             # Save the actual transaction and start a new one
             self._pool.put(self._txn)
-
-        self._txn = txn = Transaction(self, request=request)
+            self._txn.init()  # reset existing transaction
+            txn = self._txn
+        else:
+            self._txn = txn = Transaction(self, request=request)
 
         # CACHE!!