edits

Author: norareidy

source/includes/interact-data/transactions.py

@@ -1,9 +1,9 @@
-from django.db import transaction
+from django.db import transaction, DatabaseError
 from sample_mflix.models import Movie
 
 # start-transaction-decorator
 @transaction.atomic
-def run_movie_transaction():
+def insert_movie_transaction():
     Movie.objects.create(
         title="Poor Things",
         runtime=141,
@@ -12,11 +12,23 @@ def run_movie_transaction():
 # end-transaction-decorator
 
 # start-transaction-manager
-def run_movie_transaction():
+def insert_movie_transaction():
     with transaction.atomic():
         Movie.objects.create(
             title="Poor Things",
             runtime=141,
             genres=["Comedy", "Romance"]
         )
-# end-transaction-manager
+# end-transaction-manager
+
+# start-handle-errors
+movie = Movie.objects.get(
+    title="Jurassic Park",
+    released=timezone.make_aware(datetime(1993, 6, 11))
+)
+try:
+    with transaction.atomic():
+        movie.update(title="Jurassic Park I")
+except DatabaseError:
+    movie.update(title="Jurassic Park")
+# end-handle-errors

source/interact-data/transactions.txt

@@ -82,6 +82,9 @@ This decorator guarantees the atomicity of any database operations
 within the function. If the function successfully completes, the 
 changes are committed MongoDB.
 
+Examples
+~~~~~~~~
+
 The following example calls the ``create()`` method within a transaction,
 inserting a document into the ``sample_mflix.movies`` collection:
 
@@ -109,6 +112,22 @@ logic around your atomic code block. If you include error handing logic inside
 the atomic block, {+framework+} might ignore these errors, resulting in unexpected
 behavior.
 
+If a transaction does not succeed, your application does not revert any changes made
+to a model's fields. To avoid inconsistencies between your models and database documents,
+you might need to manually restore the original field values.
+
+Example
+~~~~~~~
+
+The following example includes error handling logic that reverts the modified
+``title`` value of the retrieved document if the database transaction fails:
+
+.. literalinclude:: /includes/interact-data/transactions.py
+   :start-after: start-handle-errors
+   :end-before: end-handle-errors
+   :language: python
+   :copyable:
+
 Additional Information
 ----------------------
 

source/limitations-upcoming.txt

@@ -255,7 +255,7 @@ Database and Collection Support
 
        - ``QuerySet.union()`` is not supported within a transaction.
        - If a transaction generates an error, the transaction is no longer usable.
-       - Nested atomic blocks are not supported. The outermost atomic block starts
+       - Savepoints, or nested atomic blocks, are not supported. The outermost atomic block starts
          a transaction, and any subsequent atomic blocks have no effect.
        - Migration operations do not run inside a transaction, which differs from {+framework+}'s
          default migration behavior.