Make it possible to use dot notation for setting context in reflex

In an effort to improve the api for setting the context that is
used in the final context in the reflex we introduce a dot notation
for setting the context. Ie `reflex.context.my_context = 'value'`.

For the old way of setting the context in instance variables you
now also prevented to set an instance variable that is already used
by the reflex.

sockpuppet/consumer.py

@@ -235,6 +235,14 @@ def render_page(self, reflex):
         reflex_context = {key: getattr(reflex, key) for key in instance_variables}
         reflex_context["stimulus_reflex"] = True
 
+        if not reflex.context._attr_data:
+            msg = (
+                "Setting context through instance variables is deprecated, "
+                'please use reflex.context.context_variable = "my_data"'
+            )
+            logger.warning(msg)
+        reflex_context.update(reflex.context)
+
         original_context_data = view.view_class.get_context_data
         reflex.get_context_data(**reflex_context)
         # monkey patch context method

sockpuppet/reflex.py

@@ -1,30 +1,65 @@
+from collections import UserDict
 from django.urls import resolve
 from urllib.parse import urlparse
 
 from django.test import RequestFactory
 
 PROTECTED_VARIABLES = [
     "consumer",
+    "context",
     "element",
+    "params",
     "selectors",
     "session",
     "url",
 ]
 
 
+class Context(UserDict):
+    """
+    A dictionary that keeps track of whether it's been used as dictionary
+    or if values has been set with dot notation. We expect things to be set
+    in dot notation so a warning is issued until next major version (1.0)
+    """
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._attr_data = {}
+
+    def __getitem__(self, key):
+        if not self.data.get(key) and not self._attr_data.get(key):
+            raise KeyError(key)
+        return self.data.get(key) or self._attr_data.get(key)
+
+    def __getattr__(self, key):
+        if not self.data.get(key) and not self._attr_data.get(key):
+            raise AttributeError(key)
+        return self.data.get(key) or self._attr_data.get(key)
+
+    def __setattr__(self, key, value):
+        self._attr_data[key] = value
+
+
 class Reflex:
     def __init__(self, consumer, url, element, selectors, params):
         self.consumer = consumer
-        self.url = url
+        self.context = Context()
         self.element = element
+        self.params = params
         self.selectors = selectors
         self.session = consumer.scope["session"]
-        self.params = params
-        self.context = {}
+        self.url = url
+
+        self._init_run = True
 
     def __repr__(self):
         return f"<Reflex url: {self.url}, session: {self.get_channel_id()}>"
 
+    def __setattr__(self, name, value):
+        if name in PROTECTED_VARIABLES and getattr(self, "_init_run", None):
+            raise ValueError("This instance variable is used by the reflex.")
+        super().__setattr__(name, value)
+
     def get_context_data(self, *args, **kwargs):
         if self.context:
             self.context.update(**kwargs)
@@ -45,7 +80,7 @@ def get_context_data(self, *args, **kwargs):
 
         context = view.get_context_data(**{"stimulus_reflex": True})
 
-        self.context = context
+        self.context.update(context)
         self.context.update(**kwargs)
         return self.context