managed_transaction context manager can now adopt modified objects from

  outer transaction

CHANGELOG.rst

@@ -1,7 +1,9 @@
 1.0.0a28 (unreleased)
 ---------------------
 
-- Nothing changed yet.
+- managed_transaction context manager can now adopt modified objects from
+  outer transaction
+  [vangheem]
 
 
 1.0.0a27 (2017-05-17)

guillotina/catalog/index.py

@@ -28,8 +28,10 @@ async def __call__(self, trns):
         # Commits are run in sync thread so there is no asyncloop
         search = queryUtility(ICatalogUtility)
         if search:
-            await search.remove(self.container, self.remove)
-            await search.index(self.container, self.index)
+            if len(self.remove) > 0:
+                await search.remove(self.container, self.remove)
+            if len(self.index) > 0:
+                await search.index(self.container, self.index)
 
         self.index = {}
         self.remove = []

guillotina/tests/test_transactions.py

@@ -1,5 +1,7 @@
 from guillotina.db.transaction import Transaction
 from guillotina.tests import mocks
+from guillotina.tests import utils
+from guillotina.transactions import managed_transaction
 
 
 async def test_no_tid_created_for_reads(dummy_request, loop):
@@ -16,3 +18,28 @@ async def test_tid_created_for_writes(dummy_request, loop):
     trns = Transaction(tm, dummy_request, loop=loop)
     await trns.tpc_begin(None)
     assert trns._tid is 1
+
+
+async def test_managed_transaction_with_adoption(container_requester):
+    async with await container_requester as requester:
+        request = utils.get_mocked_request(requester.db)
+        root = await utils.get_root(request)
+        async with managed_transaction(request=request, abort_when_done=True):
+            container = await root.async_get('guillotina')
+            container.title = 'changed title'
+            container._p_register()
+
+            assert container._p_oid in container._p_jar.modified
+
+            # nest it with adoption
+            async with managed_transaction(request=request, adopt_parent_txn=True):
+                # this should commit, take on parent txn for container
+                pass
+
+            # no longer modified, adopted in previous txn
+            assert container._p_oid not in container._p_jar.modified
+
+        # finally, retrieve it again and make sure it's updated
+        async with managed_transaction(request=request, abort_when_done=True):
+            container = await root.async_get('guillotina')
+            assert container.title == 'changed title'

guillotina/transactions.py

@@ -61,14 +61,17 @@ def get_transaction(request=None):
 
 
 class managed_transaction:
-    def __init__(self, request=None, tm=None, write=False, abort_when_done=False):
+    def __init__(self, request=None, tm=None, write=False, abort_when_done=False,
+                 adopt_parent_txn=False):
         self.request = _safe_get_request(request)
         if tm is None:
             tm = request._tm
         self.tm = tm
         self.write = write
         self.abort_when_done = abort_when_done
         self.previous_txn = self.txn = self.previous_write_setting = None
+        self.adopt_parent_txn = adopt_parent_txn
+        self.adopted = []
 
     async def __aenter__(self):
         if self.request is not None:
@@ -78,11 +81,46 @@ async def __aenter__(self):
                 self.request._db_write_enabled = True
         self.txn = await self.tm.begin(request=self.request)
 
+    def adopt_objects(self, obs, txn):
+        for oid, ob in obs.items():
+            self.adopted.append(ob)
+            ob._p_jar = txn
+
     async def __aexit__(self, exc_type, exc, tb):
+        if self.adopt_parent_txn:
+            # take on parent's modified, added, deleted objects if necessary
+            # before we commit or abort this transaction.
+            # this is necessary because inside this block, the outer transaction
+            # could have been attached to an object that changed.
+            # we're ready to commit and we want to potentially commit everything
+            # where, we we're adopted those objects with this transaction
+            if self.previous_txn != self.txn:
+                # try adopting currently registered objects
+                self.txn.modified = self.previous_txn.modified
+                self.txn.deleted = self.previous_txn.deleted
+                self.txn.added = self.previous_txn.added
+
+                self.adopt_objects(self.txn.modified, self.txn)
+                self.adopt_objects(self.txn.deleted, self.txn)
+                self.adopt_objects(self.txn.added, self.txn)
+
         if self.abort_when_done:
             await self.tm.abort(txn=self.txn)
         else:
             await self.tm.commit(txn=self.txn)
+
+        if self.adopt_parent_txn:
+            # restore transaction ownership of item from adoption done above
+            if self.previous_txn != self.txn:
+                # we adopted previously detetected transaction so now
+                # we need to clear changed objects and restore ownership
+                self.previous_txn.modified = {}
+                self.previous_txn.deleted = {}
+                self.previous_txn.added = {}
+
+                for ob in self.adopted:
+                    ob._p_jar = self.previous_txn
+
         if self.request is not None:
             if self.previous_txn is not None:
                 # we do not want to overwrite _txn if is it None since we can