Create and handle database atomic mutations

docs/mutations.rst

@@ -255,3 +255,95 @@ rolls back the transaction.
     inefficient when traffic increases. Opening a transaction for every request has some
     overhead. The impact on performance depends on the query patterns of your application
     and on how well your database handles locking.
+
+Check the next section for a better solution.
+
+Tying transactions to mutations
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A mutation can contain multiple fields, just like a query. There's one important
+distinction between queries and mutations, other than the name:
+
+..
+
+    `While query fields are executed in parallel, mutation fields run in series, one
+    after the other.`
+
+This means that if we send two ``incrementCredits`` mutations in one request, the first
+is guaranteed to finish before the second begins, ensuring that we don't end up with a
+race condition with ourselves.
+
+On the other hand, if the first ``incrementCredits`` runs successfully but the second
+one does not, the operation cannot be retried as it is. That's why is a good idea to
+run all mutation fields in a transaction, to guarantee all occur or nothing occurs.
+
+To enable this behavior for all databases set the graphene ``ATOMIC_MUTATIONS`` settings
+to ``True`` in your settings file:
+
+.. code:: python
+
+    GRAPHENE = {
+        # ...
+        "ATOMIC_MUTATIONS": True,
+    }
+
+On the contrary, if you want to enable this behavior for a specific database, set
+``ATOMIC_MUTATIONS`` to ``True`` in your database settings:
+
+.. code:: python
+
+    DATABASES = {
+        "default": {
+            # ...
+            "ATOMIC_MUTATIONS": True,
+        },
+        # ...
+    }
+
+Now, given the following example mutation:
+
+.. code::
+
+    mutation IncreaseCreditsTwice {
+
+        increaseCredits1: increaseCredits(input: { amount: 10 }) {
+            balance
+            errors {
+                field
+                messages
+            }
+        }
+
+        increaseCredits2: increaseCredits(input: { amount: -1 }) {
+            balance
+            errors {
+                field
+                messages
+            }
+        }
+
+    }
+
+The server is going to return something like:
+
+.. code:: json
+
+    {
+        "data": {
+            "increaseCredits1": {
+                "balance": 10.0,
+                "errors": []
+            },
+            "increaseCredits2": {
+                "balance": null,
+                "errors": [
+                    {
+                        "field": "amount",
+                        "message": "Amount should be a positive number"
+                    }
+                ]
+            },
+        }
+    }
+
+But the balance will remain the same.

graphene_django/settings.py

@@ -45,6 +45,7 @@ DEFAULTS = {
     # This sets headerEditorEnabled GraphiQL option, for details go to
     # https://github.com/graphql/graphiql/tree/main/packages/graphiql#options
     "GRAPHIQL_HEADER_EDITOR_ENABLED": True,
+    "ATOMIC_MUTATIONS": False,
 }
 
 if settings.DEBUG:

graphene_django/tests/test_views.py

@@ -6,6 +6,8 @@ from mock import patch
 
 from django.db import connection
 
+from graphene_django.settings import graphene_settings
+
 from .models import Pet
 
 try:
@@ -567,9 +569,13 @@ def test_passes_request_into_context_request(client):
 
 
 def test_form_mutation_multiple_creation_invalid_atomic_request(client):
+    old_atomic_mutations = connection.settings_dict.get("ATOMIC_MUTATIONS", False)
     old_atomic_requests = connection.settings_dict["ATOMIC_REQUESTS"]
+    old_graphene_atomic_mutations = graphene_settings.ATOMIC_MUTATIONS
     try:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = False
         connection.settings_dict["ATOMIC_REQUESTS"] = True
+        graphene_settings.ATOMIC_MUTATIONS = False
 
         query = """
         mutation PetMutations {
@@ -602,13 +608,109 @@ def test_form_mutation_multiple_creation_invalid_atomic_request(client):
         assert Pet.objects.count() == 0
 
     finally:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = old_atomic_mutations
         connection.settings_dict["ATOMIC_REQUESTS"] = old_atomic_requests
+        graphene_settings.ATOMIC_MUTATIONS = old_graphene_atomic_mutations
 
 
-def test_form_mutation_multiple_creation_invalid_non_atomic_request(client):
+def test_form_mutation_multiple_creation_invalid_atomic_mutation_1(client):
+    old_atomic_mutations = connection.settings_dict.get("ATOMIC_MUTATIONS", False)
     old_atomic_requests = connection.settings_dict["ATOMIC_REQUESTS"]
+    old_graphene_atomic_mutations = graphene_settings.ATOMIC_MUTATIONS
     try:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = True
         connection.settings_dict["ATOMIC_REQUESTS"] = False
+        graphene_settings.ATOMIC_MUTATIONS = False
+
+        query = """
+        mutation PetMutations {
+            petFormMutation1: petFormMutation(input: { name: "Mia", age: 99 }) {
+                errors {
+                    field
+                    messages
+                }
+            }
+            petFormMutation2: petFormMutation(input: { name: "Enzo", age: 0 }) {
+                errors {
+                    field
+                    messages
+                }
+            }
+        }
+        """
+
+        response = client.post(url_string(query=query))
+        content = response_json(response)
+
+        assert "errors" not in content
+
+        assert content["data"]["petFormMutation1"]["errors"] == [
+            {"field": "age", "messages": ["Too old"]}
+        ]
+
+        assert content["data"]["petFormMutation2"]["errors"] == []
+
+        assert Pet.objects.count() == 0
+
+    finally:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = old_atomic_mutations
+        connection.settings_dict["ATOMIC_REQUESTS"] = old_atomic_requests
+        graphene_settings.ATOMIC_MUTATIONS = old_graphene_atomic_mutations
+
+
+def test_form_mutation_multiple_creation_invalid_atomic_mutation_2(client):
+    old_atomic_mutations = connection.settings_dict.get("ATOMIC_MUTATIONS", False)
+    old_atomic_requests = connection.settings_dict["ATOMIC_REQUESTS"]
+    old_graphene_atomic_mutations = graphene_settings.ATOMIC_MUTATIONS
+    try:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = False
+        connection.settings_dict["ATOMIC_REQUESTS"] = False
+        graphene_settings.ATOMIC_MUTATIONS = True
+
+        query = """
+        mutation PetMutations {
+            petFormMutation1: petFormMutation(input: { name: "Mia", age: 99 }) {
+                errors {
+                    field
+                    messages
+                }
+            }
+            petFormMutation2: petFormMutation(input: { name: "Enzo", age: 0 }) {
+                errors {
+                    field
+                    messages
+                }
+            }
+        }
+        """
+
+        response = client.post(url_string(query=query))
+        content = response_json(response)
+
+        assert "errors" not in content
+
+        assert content["data"]["petFormMutation1"]["errors"] == [
+            {"field": "age", "messages": ["Too old"]}
+        ]
+
+        assert content["data"]["petFormMutation2"]["errors"] == []
+
+        assert Pet.objects.count() == 0
+
+    finally:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = old_atomic_mutations
+        connection.settings_dict["ATOMIC_REQUESTS"] = old_atomic_requests
+        graphene_settings.ATOMIC_MUTATIONS = old_graphene_atomic_mutations
+
+
+def test_form_mutation_multiple_creation_invalid_non_atomic(client):
+    old_atomic_mutations = connection.settings_dict.get("ATOMIC_MUTATIONS", False)
+    old_atomic_requests = connection.settings_dict["ATOMIC_REQUESTS"]
+    old_graphene_atomic_mutations = graphene_settings.ATOMIC_MUTATIONS
+    try:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = False
+        connection.settings_dict["ATOMIC_REQUESTS"] = False
+        graphene_settings.ATOMIC_MUTATIONS = False
 
         query = """
         mutation PetMutations {
@@ -645,13 +747,19 @@ def test_form_mutation_multiple_creation_invalid_non_atomic_request(client):
         assert pet.age == 0
 
     finally:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = old_atomic_mutations
         connection.settings_dict["ATOMIC_REQUESTS"] = old_atomic_requests
+        graphene_settings.ATOMIC_MUTATIONS = old_graphene_atomic_mutations
 
 
 def test_model_form_mutation_multiple_creation_invalid_atomic_request(client):
+    old_atomic_mutations = connection.settings_dict.get("ATOMIC_MUTATIONS", False)
     old_atomic_requests = connection.settings_dict["ATOMIC_REQUESTS"]
+    old_graphene_atomic_mutations = graphene_settings.ATOMIC_MUTATIONS
     try:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = False
         connection.settings_dict["ATOMIC_REQUESTS"] = True
+        graphene_settings.ATOMIC_MUTATIONS = False
 
         query = """
         mutation PetMutations {
@@ -693,13 +801,19 @@ def test_model_form_mutation_multiple_creation_invalid_atomic_request(client):
         assert Pet.objects.count() == 0
 
     finally:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = old_atomic_mutations
         connection.settings_dict["ATOMIC_REQUESTS"] = old_atomic_requests
+        graphene_settings.ATOMIC_MUTATIONS = old_graphene_atomic_mutations
 
 
-def test_model_form_mutation_multiple_creation_invalid_non_atomic_request(client):
+def test_model_form_mutation_multiple_creation_invalid_non_atomic(client):
+    old_atomic_mutations = connection.settings_dict.get("ATOMIC_MUTATIONS", False)
     old_atomic_requests = connection.settings_dict["ATOMIC_REQUESTS"]
+    old_graphene_atomic_mutations = graphene_settings.ATOMIC_MUTATIONS
     try:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = False
         connection.settings_dict["ATOMIC_REQUESTS"] = False
+        graphene_settings.ATOMIC_MUTATIONS = False
 
         query = """
         mutation PetMutations {
@@ -745,30 +859,44 @@ def test_model_form_mutation_multiple_creation_invalid_non_atomic_request(client
         assert pet.age == 0
 
     finally:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = old_atomic_mutations
         connection.settings_dict["ATOMIC_REQUESTS"] = old_atomic_requests
+        graphene_settings.ATOMIC_MUTATIONS = old_graphene_atomic_mutations
 
 
 @patch("rest_framework.views.transaction.set_rollback")
 def test_query_errors_atomic_request(set_rollback_mock, client):
+    old_atomic_mutations = connection.settings_dict.get("ATOMIC_MUTATIONS", False)
     old_atomic_requests = connection.settings_dict["ATOMIC_REQUESTS"]
+    old_graphene_atomic_mutations = graphene_settings.ATOMIC_MUTATIONS
     try:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = False
         connection.settings_dict["ATOMIC_REQUESTS"] = True
+        graphene_settings.ATOMIC_MUTATIONS = False
 
         client.get(url_string(query="force error"))
         set_rollback_mock.assert_called_once_with(True)
 
     finally:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = old_atomic_mutations
         connection.settings_dict["ATOMIC_REQUESTS"] = old_atomic_requests
+        graphene_settings.ATOMIC_MUTATIONS = old_graphene_atomic_mutations
 
 
 @patch("rest_framework.views.transaction.set_rollback")
-def test_query_errors_non_atomic_request(set_rollback_mock, client):
+def test_query_errors_non_atomic(set_rollback_mock, client):
+    old_atomic_mutations = connection.settings_dict.get("ATOMIC_MUTATIONS", False)
     old_atomic_requests = connection.settings_dict["ATOMIC_REQUESTS"]
+    old_graphene_atomic_mutations = graphene_settings.ATOMIC_MUTATIONS
     try:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = False
         connection.settings_dict["ATOMIC_REQUESTS"] = False
+        graphene_settings.ATOMIC_MUTATIONS = False
 
         client.get(url_string(query="force error"))
         set_rollback_mock.assert_not_called()
 
     finally:
+        connection.settings_dict["ATOMIC_MUTATIONS"] = old_atomic_mutations
         connection.settings_dict["ATOMIC_REQUESTS"] = old_atomic_requests
+        graphene_settings.ATOMIC_MUTATIONS = old_graphene_atomic_mutations

graphene_django/views.py

@@ -3,6 +3,7 @@ import json
 import re
 
 import six
+from django.db import connection, transaction
 from django.http import HttpResponse, HttpResponseNotAllowed
 from django.http.response import HttpResponseBadRequest
 from django.shortcuts import render
@@ -320,14 +321,27 @@ class GraphQLView(View):
                 # executor is not a valid argument in all backends
                 extra_options["executor"] = self.executor
 
-            return document.execute(
+            operation_type = document.get_operation_type(operation_name)
-                root_value=self.get_root_value(request),
+            options = {
-                variable_values=variables,
+                "root_value": self.get_root_value(request),
-                operation_name=operation_name,
+                "variable_values": variables,
-                context_value=self.get_context(request),
+                "operation_name": operation_name,
-                middleware=self.get_middleware(request),
+                "context_value": self.get_context(request),
-                **extra_options
+                "middleware": self.get_middleware(request),
-            )
+                **extra_options,
+            }
+
+            if operation_type == "mutation" and (
+                graphene_settings.ATOMIC_MUTATIONS is True
+                or connection.settings_dict.get("ATOMIC_MUTATIONS", False) is True
+            ):
+                with transaction.atomic():
+                    result = document.execute(**options)
+                    if getattr(request, MUTATION_ERRORS_FLAG, False) is True:
+                        transaction.set_rollback(True)
+                return result
+
+            return document.execute(**options)
         except Exception as e:
             return ExecutionResult(errors=[e], invalid=True)