Merge pull request #176 from graphql-python/features/middlewares

Added Middleware

Author: syrusakbary

docs/config.toml

@@ -17,6 +17,7 @@ ga = "UA-12613282-7"
     "/docs/basic-types/",
     "/docs/enums/",
     "/docs/relay/",
+    "/docs/middleware/",
   ]
 
 [docs.django]

docs/pages/docs/django/debug.md

@@ -13,14 +13,19 @@ For that, you will need to add the plugin in your graphene schema.
 
 ## Installation
 
-For use the Django Debug plugin in Graphene, just import `DjangoDebugPlugin` and add it to the `plugins` argument when you initiate the `Schema`.
+For use the Django Debug plugin in Graphene:
+* Import `DjangoDebugMiddleware` and add it to the `middleware` argument when you initiate the `Schema`.
+* Add the `debug` field into the schema root `Query` with the value `graphene.Field(DjangoDebug, name='__debug')`.
 
 
 ```python
-from graphene.contrib.django.debug import DjangoDebugPlugin
+from graphene.contrib.django.debug import DjangoDebugMiddleware, DjangoDebug
 
-# ...
-schema = graphene.Schema(query=Query, plugins=[DjangoDebugPlugin()])
+class Query(graphene.ObjectType):
+    # ...
+    debug = graphene.Field(DjangoDebug, name='__debug')
+
+schema = graphene.Schema(query=Query, middlewares=[DjangoDebugMiddleware()])
 ```
 
 This plugin, will add another field in the `Query` named `__debug`.

docs/pages/docs/middleware.md

@@ -0,0 +1,43 @@
+---
+title: Middleware
+description: Walkthrough Middleware
+---
+
+# Middleware
+
+You can use _middleware_ to affect the evaluation of fields in your schema.
+
+A middleware is any object that responds to `resolve(*args, next_middleware)`. Inside that method, it should either:
+
+* Send `resolve` to the next middleware to continue the evaluation; or
+* Return a value to end the evaluation early.
+
+Middlewares' `resolve` is invoked with several arguments:
+
+* `next` represents the execution chain. Call `next` to continue evalution.
+* `root` is the root value object passed throughout the query
+* `args` is the hash of arguments passed to the field
+* `context` is the context object passed throughout the query
+* `info` is the resolver info
+
+Add a middleware to a schema by adding to the `middlewares` list.
+
+
+### Example: Authorization
+
+This middleware only continues evaluation if the `field_name` is not `'user'`:
+
+```python
+class AuthorizationMiddleware(object):
+
+    def resolve(self, next, root, args, context, info):
+        if info.field_name == 'user':
+            return None
+        return next(root, args, context, info)
+```
+
+Then, add the middleware to your schema:
+
+```python
+schema = Schema(middlewares=[AuthorizationMiddleware])
+```

graphene/contrib/django/debug/__init__.py

@@ -1,4 +1,4 @@
-from .plugin import DjangoDebugPlugin
+from .middleware import DjangoDebugMiddleware
 from .types import DjangoDebug
 
-__all__ = ['DjangoDebugPlugin', 'DjangoDebug']
+__all__ = ['DjangoDebugMiddleware', 'DjangoDebug']

graphene/contrib/django/debug/middleware.py

@@ -0,0 +1,56 @@
+from promise import Promise
+from django.db import connections
+
+from .sql.tracking import unwrap_cursor, wrap_cursor
+from .types import DjangoDebug
+
+
+class DjangoDebugContext(object):
+
+    def __init__(self):
+        self.debug_promise = None
+        self.promises = []
+        self.enable_instrumentation()
+        self.object = DjangoDebug(sql=[])
+
+    def get_debug_promise(self):
+        if not self.debug_promise:
+            self.debug_promise = Promise.all(self.promises)
+        return self.debug_promise.then(self.on_resolve_all_promises)
+
+    def on_resolve_all_promises(self, values):
+        self.disable_instrumentation()
+        return self.object
+
+    def add_promise(self, promise):
+        if self.debug_promise and not self.debug_promise.is_fulfilled:
+            self.promises.append(promise)
+
+    def enable_instrumentation(self):
+        # This is thread-safe because database connections are thread-local.
+        for connection in connections.all():
+            wrap_cursor(connection, self)
+
+    def disable_instrumentation(self):
+        for connection in connections.all():
+            unwrap_cursor(connection)
+
+
+class DjangoDebugMiddleware(object):
+
+    def resolve(self, next, root, args, context, info):
+        django_debug = getattr(context, 'django_debug', None)
+        if not django_debug:
+            if context is None:
+                raise Exception('DjangoDebug cannot be executed in None contexts')
+            try:
+                context.django_debug = DjangoDebugContext()
+            except Exception:
+                raise Exception('DjangoDebug need the context to be writable, context received: {}.'.format(
+                    context.__class__.__name__
+                ))
+        if info.schema.graphene_schema.T(DjangoDebug) == info.return_type:
+            return context.django_debug.get_debug_promise()
+        promise = next(root, args, context, info)
+        context.django_debug.add_promise(promise)
+        return promise

graphene/contrib/django/debug/plugin.py

@@ -8,6 +8,8 @@
 from django.utils import six
 from django.utils.encoding import force_text
 
+from .types import DjangoDebugSQL, DjangoDebugPostgreSQL
+
 
 class SQLQueryTriggered(Exception):
     """Thrown when template panel triggers a query"""
@@ -139,9 +141,11 @@ def _record(self, method, sql, params):
                     'iso_level': iso_level,
                     'encoding': conn.encoding,
                 })
-
+                _sql = DjangoDebugPostgreSQL(**params)
+            else:
+                _sql = DjangoDebugSQL(**params)
             # We keep `sql` to maintain backwards compatibility
-            self.logger.record(**params)
+            self.logger.object.sql.append(_sql)
 
     def callproc(self, procname, params=()):
         return self._record(self.cursor.callproc, procname, params)

graphene/contrib/django/debug/sql/tracking.py

@@ -1,7 +1,7 @@
 from .....core import Boolean, Float, ObjectType, String
 
 
-class DjangoDebugSQL(ObjectType):
+class DjangoDebugBaseSQL(ObjectType):
     vendor = String()
     alias = String()
     sql = String()
@@ -13,6 +13,12 @@ class DjangoDebugSQL(ObjectType):
     is_slow = Boolean()
     is_select = Boolean()
 
+
+class DjangoDebugSQL(DjangoDebugBaseSQL):
+    pass
+
+
+class DjangoDebugPostgreSQL(DjangoDebugBaseSQL):
     trans_id = String()
     trans_status = String()
     iso_level = String()

graphene/contrib/django/debug/sql/types.py

@@ -5,7 +5,12 @@
 from graphene.contrib.django.utils import DJANGO_FILTER_INSTALLED
 
 from ...tests.models import Reporter
-from ..plugin import DjangoDebugPlugin
+from ..middleware import DjangoDebugMiddleware
+from ..types import DjangoDebug
+
+
+class context(object):
+    pass
 
 # from examples.starwars_django.models import Character
 
@@ -25,6 +30,7 @@ class Meta:
 
     class Query(graphene.ObjectType):
         reporter = graphene.Field(ReporterType)
+        debug = graphene.Field(DjangoDebug, name='__debug')
 
         def resolve_reporter(self, *args, **kwargs):
             return Reporter.objects.first()
@@ -51,8 +57,8 @@ def resolve_reporter(self, *args, **kwargs):
             }]
         }
     }
-    schema = graphene.Schema(query=Query, plugins=[DjangoDebugPlugin()])
-    result = schema.execute(query)
+    schema = graphene.Schema(query=Query, middlewares=[DjangoDebugMiddleware()])
+    result = schema.execute(query, context_value=context())
     assert not result.errors
     assert result.data == expected
 
@@ -70,6 +76,7 @@ class Meta:
 
     class Query(graphene.ObjectType):
         all_reporters = ReporterType.List()
+        debug = graphene.Field(DjangoDebug, name='__debug')
 
         def resolve_all_reporters(self, *args, **kwargs):
             return Reporter.objects.all()
@@ -98,8 +105,8 @@ def resolve_all_reporters(self, *args, **kwargs):
             }]
         }
     }
-    schema = graphene.Schema(query=Query, plugins=[DjangoDebugPlugin()])
-    result = schema.execute(query)
+    schema = graphene.Schema(query=Query, middlewares=[DjangoDebugMiddleware()])
+    result = schema.execute(query, context_value=context())
     assert not result.errors
     assert result.data == expected
 
@@ -117,6 +124,7 @@ class Meta:
 
     class Query(graphene.ObjectType):
         all_reporters = DjangoConnectionField(ReporterType)
+        debug = graphene.Field(DjangoDebug, name='__debug')
 
         def resolve_all_reporters(self, *args, **kwargs):
             return Reporter.objects.all()
@@ -146,8 +154,8 @@ def resolve_all_reporters(self, *args, **kwargs):
             }]
         },
     }
-    schema = graphene.Schema(query=Query, plugins=[DjangoDebugPlugin()])
-    result = schema.execute(query)
+    schema = graphene.Schema(query=Query, middlewares=[DjangoDebugMiddleware()])
+    result = schema.execute(query, context_value=context())
     assert not result.errors
     assert result.data['allReporters'] == expected['allReporters']
     assert 'COUNT' in result.data['__debug']['sql'][0]['rawSql']
@@ -172,6 +180,7 @@ class Meta:
 
     class Query(graphene.ObjectType):
         all_reporters = DjangoFilterConnectionField(ReporterType)
+        debug = graphene.Field(DjangoDebug, name='__debug')
 
         def resolve_all_reporters(self, *args, **kwargs):
             return Reporter.objects.all()
@@ -201,8 +210,8 @@ def resolve_all_reporters(self, *args, **kwargs):
             }]
         },
     }
-    schema = graphene.Schema(query=Query, plugins=[DjangoDebugPlugin()])
-    result = schema.execute(query)
+    schema = graphene.Schema(query=Query, middlewares=[DjangoDebugMiddleware()])
+    result = schema.execute(query, context_value=context())
     assert not result.errors
     assert result.data['allReporters'] == expected['allReporters']
     assert 'COUNT' in result.data['__debug']['sql'][0]['rawSql']

graphene/contrib/django/debug/tests/test_query.py

@@ -1,7 +1,7 @@
 from ....core.classtypes.objecttype import ObjectType
 from ....core.types import Field
-from .sql.types import DjangoDebugSQL
+from .sql.types import DjangoDebugBaseSQL
 
 
 class DjangoDebug(ObjectType):
-    sql = Field(DjangoDebugSQL.List())
+    sql = Field(DjangoDebugBaseSQL.List())