Add global Request Adapter (#6)

* ∙ - remove contextvar from flask and quart only FastApi now relies on that
∙ - backend __init__ now holds the global request adapter and backend which get set on app initialisation
∙ request adapter and server can now be call from everywhere after the app initialised
∙ - added normal top level imports because the modules get matching loaded - but bad Import Error message when quart or equivilent are not installed
∙ - added _ as prefix to backends to avoid importing errors with their underlying
∙ - Can now move to remove unnecessary passing of the server object
∙

* Moved get_server_type to backends

* ∙ moved async validation to validation
∙ replaced request.get_path with request.path
∙

* Moved custom backend check to _validation.py

* Removed server injection of server methods - they use self.server now

* removed use_async from dispatch server methods and use dash_app._use_async
removed remaining set request process from flask

* adding custom error handling per backend, tests and adjustments to the flow. Made endpoints for downloading the reqs

* adjusments for formatting

* adjustment to retest backend

* Added Dash app as type to servers

* adding missing reqs association

* Addedd basic typing to servers

* fixing minor linting issues

* Fixed weird AI shit

* Cleanup before heavy pull

* Merged latest changes

* f rebase

* f rebase

* Added Dash app as type to servers

* Addedd basic typing to servers

---------

Co-authored-by: Christian Giessel <cgiessel@tesla.com>
Co-authored-by: BSd3v <82055130+BSd3v@users.noreply.github.com>

Author: 3 people

dash/_callback.py

@@ -1,12 +1,8 @@
+from typing import Callable, Optional, Any, List, Tuple, Union
+from functools import wraps
 import collections
 import hashlib
-from functools import wraps
-
-from typing import Callable, Optional, Any, List, Tuple, Union
-
-
 import asyncio
-from dash.backend import get_request_adapter
 
 from .dependencies import (
     handle_callback_args,
@@ -39,10 +35,11 @@
     clean_property_name,
 )
 
-from . import _validate
 from .background_callback.managers import BaseBackgroundCallbackManager
 from ._callback_context import context_value
 from ._no_update import NoUpdate
+from . import _validate
+from . import backends
 
 
 async def _async_invoke_callback(
@@ -176,7 +173,6 @@ def callback(
             Note that the endpoint will not appear in the list of registered
             callbacks in the Dash devtools.
     """
-
     background_spec = None
 
     config_prevent_initial_callbacks = _kwargs.pop(
@@ -376,7 +372,8 @@ def _get_callback_manager(
                 " and store results on redis.\n"
             )
 
-    old_job = get_request_adapter().get_args().getlist("oldJob")
+    adapter = backends.request_adapter()
+    old_job = adapter.args.getlist("oldJob") if hasattr(adapter.args, "getlist") else []
 
     if old_job:
         for job in old_job:
@@ -390,21 +387,20 @@ def _setup_background_callback(
 ):
     """Set up the background callback and manage jobs."""
     callback_manager = _get_callback_manager(kwargs, background)
+    if not callback_manager:
+        return to_json({"error": "No background callback manager configured"})
 
     progress_outputs = background.get("progress")
 
     cache_ignore_triggered = background.get("cache_ignore_triggered", True)
 
     cache_key = callback_manager.build_cache_key(
         func,
-        # Inputs provided as dict is kwargs.
         func_args if func_args else func_kwargs,
         background.get("cache_args_to_ignore", []),
         None if cache_ignore_triggered else callback_ctx.get("triggered_inputs", []),
     )
-
     job_fn = callback_manager.func_registry.get(background_key)
-
     ctx_value = AttributeDict(**context_value.get())
     ctx_value.ignore_register_page = True
     ctx_value.pop("background_callback_manager")
@@ -436,7 +432,8 @@ def _setup_background_callback(
 
 def _progress_background_callback(response, callback_manager, background):
     progress_outputs = background.get("progress")
-    cache_key = get_request_adapter().get_args().get("cacheKey")
+    adapter = backends.request_adapter()
+    cache_key = adapter.args.get("cacheKey")
 
     if progress_outputs:
         # Get the progress before the result as it would be erased after the results.
@@ -453,8 +450,9 @@ def _update_background_callback(
     """Set up the background callback and manage jobs."""
     callback_manager = _get_callback_manager(kwargs, background)
 
-    cache_key = get_request_adapter().get_args().get("cacheKey")
-    job_id = get_request_adapter().get_args().get("job")
+    adapter = backends.request_adapter()
+    cache_key = adapter.args.get("cacheKey") if adapter else None
+    job_id = adapter.args.get("job") if adapter else None
 
     _progress_background_callback(response, callback_manager, background)
 
@@ -474,8 +472,9 @@ def _handle_rest_background_callback(
     multi,
     has_update=False,
 ):
-    cache_key = get_request_adapter().get_args().get("cacheKey")
-    job_id = get_request_adapter().get_args().get("job")
+    adapter = backends.request_adapter()
+    cache_key = adapter.args.get("cacheKey") if adapter else None
+    job_id = adapter.args.get("job") if adapter else None
     # Must get job_running after get_result since get_results terminates it.
     job_running = callback_manager.job_running(job_id)
     if not job_running and output_value is callback_manager.UNDEFINED:
@@ -688,10 +687,11 @@ def add_context(*args, **kwargs):
             )
 
             response: dict = {"multi": True}
-            jsonResponse = None
+            jsonResponse: Optional[str] = None
             try:
                 if background is not None:
-                    if not get_request_adapter().get_args().get("cacheKey"):
+                    adapter = backends.request_adapter()
+                    if not (adapter and adapter.args.get("cacheKey")):
                         return _setup_background_callback(
                             kwargs,
                             background,
@@ -762,7 +762,8 @@ async def async_add_context(*args, **kwargs):
 
             try:
                 if background is not None:
-                    if not get_request_adapter().get_args().get("cacheKey"):
+                    adapter = backends.request_adapter()
+                    if not (adapter and adapter.args.get("cacheKey")):
                         return _setup_background_callback(
                             kwargs,
                             background,

dash/_pages.py

@@ -318,18 +318,22 @@ def register_page(
     )
     page.update(
         supplied_title=title,
-        title=title
-        if title is not None
-        else CONFIG.title
-        if CONFIG.title != "Dash"
-        else page["name"],
+        title=(
+            title
+            if title is not None
+            else CONFIG.title
+            if CONFIG.title != "Dash"
+            else page["name"]
+        ),
     )
     page.update(
-        description=description
-        if description
-        else CONFIG.description
-        if CONFIG.description
-        else "",
+        description=(
+            description
+            if description
+            else CONFIG.description
+            if CONFIG.description
+            else ""
+        ),
         order=order,
         supplied_order=order,
         supplied_layout=layout,
@@ -390,15 +394,13 @@ def _path_to_page(path_id):
 
 
 def _page_meta_tags(app, request):
-    request_path = request.get_path()
+    request_path = request.path
     start_page, path_variables = _path_to_page(request_path.strip("/"))
 
     image = start_page.get("image", "")
     if image:
         image = app.get_asset_url(image)
-    assets_image_url = (
-        "".join([request.get_root(), image.lstrip("/")]) if image else None
-    )
+    assets_image_url = "".join([request.root, image.lstrip("/")]) if image else None
     supplied_image_url = start_page.get("image_url")
     image_url = supplied_image_url if supplied_image_url else assets_image_url
 
@@ -413,7 +415,7 @@ def _page_meta_tags(app, request):
     return [
         {"name": "description", "content": description},
         {"property": "twitter:card", "content": "summary_large_image"},
-        {"property": "twitter:url", "content": request.get_url()},
+        {"property": "twitter:url", "content": request.url},
         {"property": "twitter:title", "content": title},
         {"property": "twitter:description", "content": description},
         {"property": "twitter:image", "content": image_url or ""},

dash/_validate.py

@@ -8,6 +8,7 @@
 from ._grouping import grouping_len, map_grouping
 from ._no_update import NoUpdate
 from .development.base_component import Component
+from . import backends
 from . import exceptions
 from ._utils import (
     patch_collections_abc,
@@ -585,3 +586,41 @@ def _valid(out):
         return
 
     _valid(output)
+
+
+def check_async(use_async):
+    if use_async is None:
+        try:
+            import asgiref  # pylint: disable=unused-import, import-outside-toplevel # noqa
+
+            use_async = True
+        except ImportError:
+            pass
+    elif use_async:
+        try:
+            import asgiref  # pylint: disable=unused-import, import-outside-toplevel # noqa
+        except ImportError as exc:
+            raise Exception(
+                "You are trying to use dash[async] without having installed the requirements please install via: `pip install dash[async]`"
+            ) from exc
+
+
+def check_backend(backend, inferred_backend):
+    if backend is not None:
+        if isinstance(backend, type):
+            # get_backend returns the backend class for a string
+            # So we compare the class names
+            expected_backend_cls, _ = backends.get_backend(inferred_backend)
+            if (
+                backend.__module__ != expected_backend_cls.__module__
+                or backend.__name__ != expected_backend_cls.__name__
+            ):
+                raise ValueError(
+                    f"Conflict between provided backend '{backend.__name__}' and server type '{inferred_backend}'."
+                )
+        elif not isinstance(backend, str):
+            raise ValueError("Invalid backend argument")
+        elif backend.lower() != inferred_backend:
+            raise ValueError(
+                f"Conflict between provided backend '{backend}' and server type '{inferred_backend}'."
+            )