Merge branch 'dev2' into api-exposure-callbacks

Author: BSd3v

CHANGELOG.md

@@ -6,10 +6,13 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ## Added
 - [#3395](https://github.com/plotly/dash/pull/3396) Add position argument to hooks.devtool
+- [#3403](https://github.com/plotly/dash/pull/3403) Add app_context to get_app, allowing to get the current app in routes.
+- [#3407](https://github.com/plotly/dash/pull/3407) Add `hidden` to callback arguments, hiding the callback from appearing in the devtool callback graph.
 
 ## Fixed
 - [#3395](https://github.com/plotly/dash/pull/3395) Fix Components added through set_props() cannot trigger related callback functions. Fix [#3316](https://github.com/plotly/dash/issues/3316)
 - [#3397](https://github.com/plotly/dash/pull/3397) Add optional callbacks, suppressing callback warning for missing component ids for a single callback.
+- [#3415](https://github.com/plotly/dash/pull/3415) Fix the error triggered when only a single no_update is returned for client-side callback functions with multiple Outputs. Fix [#3366](https://github.com/plotly/dash/issues/3366)
 
 ## [3.2.0] - 2025-07-31
 

CITATION.cff

@@ -9,7 +9,7 @@ authors:
   given-names: "Alex"
   orcid: https://orcid.org/0000-0003-4623-4147
 title: "A data and analytics web app framework for Python, no JavaScript required."
-version: 2.18.2
+version: 3.2.0
 doi: 10.5281/zenodo.14182630
-date-released: 2024-11-04
+date-released: 2025-07-31
 url: https://github.com/plotly/dash

dash/_callback.py

@@ -65,7 +65,7 @@ def _invoke_callback(func, *args, **kwargs):  # used to mark the frame for the d
 GLOBAL_API_PATHS = {}
 
 
-# pylint: disable=too-many-locals
+# pylint: disable=too-many-locals,too-many-arguments
 def callback(
     *_args,
     background: bool = False,
@@ -80,6 +80,7 @@ def callback(
     on_error: Optional[Callable[[Exception], Any]] = None,
     api_endpoint: Optional[str] = None,
     optional: Optional[bool] = False,
+    hidden: Optional[bool] = False,
     **_kwargs,
 ) -> Callable[..., Any]:
     """
@@ -164,6 +165,8 @@ def callback(
             to access the original callback inputs, states and output.
         :param optional:
             Mark all dependencies as not required on the initial layout checks.
+        :param hidden:
+            Hide the callback from the devtools callbacks tab.
     """
 
     background_spec = None
@@ -222,6 +225,7 @@ def callback(
         on_error=on_error,
         api_endpoint=api_endpoint,
         optional=optional,
+        hidden=hidden,
     )
 
 
@@ -268,6 +272,7 @@ def insert_callback(
     dynamic_creator: Optional[bool] = False,
     no_output=False,
     optional=False,
+    hidden=False,
 ):
     if prevent_initial_call is None:
         prevent_initial_call = config_prevent_initial_callbacks
@@ -292,6 +297,7 @@ def insert_callback(
         "dynamic_creator": dynamic_creator,
         "no_output": no_output,
         "optional": optional,
+        "hidden": hidden,
     }
     if running:
         callback_spec["running"] = running
@@ -641,6 +647,7 @@ def register_callback(
         running=running,
         no_output=not has_output,
         optional=_kwargs.get("optional", False),
+        hidden=_kwargs.get("hidden", False),
     )
 
     # pylint: disable=too-many-locals

dash/_get_app.py

@@ -1,16 +1,58 @@
+import functools
+
+from contextvars import ContextVar, copy_context
 from textwrap import dedent
 
 APP = None
 
+app_context = ContextVar("dash_app_context")
+
+
+def with_app_context(func):
+    @functools.wraps(func)
+    def wrap(self, *args, **kwargs):
+        app_context.set(self)
+        ctx = copy_context()
+        return ctx.run(func, self, *args, **kwargs)
+
+    return wrap
+
+
+def with_app_context_async(func):
+    @functools.wraps(func)
+    async def wrap(self, *args, **kwargs):
+        app_context.set(self)
+        ctx = copy_context()
+        print("copied and set")
+        return await ctx.run(func, self, *args, **kwargs)
+
+    return wrap
+
+
+def with_app_context_factory(func, app):
+    @functools.wraps(func)
+    def wrap(*args, **kwargs):
+        app_context.set(app)
+        ctx = copy_context()
+        return ctx.run(func, *args, **kwargs)
+
+    return wrap
+
 
 def get_app():
+    try:
+        ctx_app = app_context.get()
+        if ctx_app is not None:
+            return ctx_app
+    except LookupError:
+        pass
+
     if APP is None:
         raise Exception(
             dedent(
                 """
                 App object is not yet defined.  `app = dash.Dash()` needs to be run
-                before `dash.get_app()` is called and can only be used within apps that use
-                the `pages` multi-page app feature: `dash.Dash(use_pages=True)`.
+                before `dash.get_app()`.
 
                 `dash.get_app()` is used to get around circular import issues when Python files
                 within the pages/` folder need to reference the `app` object.

dash/dash-renderer/package-lock.json

@@ -226,8 +226,16 @@ function refErr(errors: any, paths: any) {
 const getVals = (input: any) =>
     Array.isArray(input) ? pluck('value', input) : input.value;
 
-const zipIfArray = (a: any, b: any) =>
-    Array.isArray(a) ? zip(a, b) : [[a, b]];
+const zipIfArray = (a: any, b: any) => {
+    if (Array.isArray(a)) {
+        // For client-side callbacks with multiple Outputs, only return a single dash_clientside.no_update
+        if (b === (window as any).dash_clientside.no_update) {
+            return zip(a, [b]);
+        }
+        return zip(a, b);
+    }
+    return [[a, b]];
+};
 
 function cleanOutputProp(property: string) {
     return property.split('@')[0];

dash/dash-renderer/src/actions/callbacks.ts

@@ -78,7 +78,11 @@ function generateElements(graphs, profile, extraLinks) {
         });
     }
 
-    (graphs.callbacks || []).forEach((callback, i) => {
+    (graphs.callbacks || []).reduce((visibleIndex, callback) => {
+        if (callback.hidden) {
+            return visibleIndex;
+        }
+
         const cb = `__dash_callback__.${callback.output}`;
         const cbProfile = profile.callbacks[callback.output] || {};
         const count = cbProfile.count || 0;
@@ -87,7 +91,7 @@ function generateElements(graphs, profile, extraLinks) {
         elements.push({
             data: {
                 id: cb,
-                label: `callback.${i}`,
+                label: `callback.${visibleIndex}`,
                 type: 'callback',
                 mode: callback.clientside_function ? 'client' : 'server',
                 count: count,
@@ -97,21 +101,23 @@ function generateElements(graphs, profile, extraLinks) {
             }
         });
 
-        callback.outputs.map(({id, property}) => {
+        callback.outputs.forEach(({id, property}) => {
             const nodeId = recordNode(id, property);
             recordEdge(cb, nodeId, 'output');
         });
 
-        callback.inputs.map(({id, property}) => {
+        callback.inputs.forEach(({id, property}) => {
             const nodeId = recordNode(id, property);
             recordEdge(nodeId, cb, 'input');
         });
 
-        callback.state.map(({id, property}) => {
+        callback.state.forEach(({id, property}) => {
             const nodeId = recordNode(id, property);
             recordEdge(nodeId, cb, 'state');
         });
-    });
+
+        return visibleIndex + 1;
+    }, 0);
 
     // pull together props in the same component
     if (extraLinks) {

dash/dash-renderer/src/components/error/CallbackGraph/CallbackGraphContainer.react.js

@@ -68,6 +68,7 @@
 from . import _watch
 from . import _get_app
 
+from ._get_app import with_app_context, with_app_context_async, with_app_context_factory
 from ._grouping import map_grouping, grouping_len, update_args_group
 from ._obsolete import ObsoleteChecker
 
@@ -774,7 +775,11 @@ def _setup_routes(self):
             )
 
         for hook in self._hooks.get_hooks("routes"):
-            self._add_url(hook.data["name"], hook.func, hook.data["methods"])
+            self._add_url(
+                hook.data["name"],
+                with_app_context_factory(hook.func, self),
+                hook.data["methods"],
+            )
 
         # catch-all for front-end routes, used by dcc.Location
         self._add_url("<path:path>", self.index)
@@ -876,6 +881,7 @@ def index_string(self, value: str) -> None:
         _validate.validate_index("index string", checks, value)
         self._index_string = value
 
+    @with_app_context
     def serve_layout(self):
         layout = self._layout_value()
 
@@ -1179,6 +1185,7 @@ def serve_component_suites(self, package_name, fingerprinted_path):
 
         return response
 
+    @with_app_context
     def index(self, *args, **kwargs):  # pylint: disable=unused-argument
         scripts = self._generate_scripts_html()
         css = self._generate_css_dist_html()
@@ -1292,6 +1299,7 @@ def interpolate_index(self, **kwargs):
             app_entry=app_entry,
         )
 
+    @with_app_context
     def dependencies(self):
         return flask.Response(
             to_json(self._callback_list),
@@ -1501,6 +1509,7 @@ def _execute_callback(self, func, args, outputs_list, g):
         )
         return partial_func
 
+    @with_app_context_async
     async def async_dispatch(self):
         body = flask.request.get_json()
         g = self._initialize_context(body)
@@ -1520,6 +1529,7 @@ async def async_dispatch(self):
         g.dash_response.set_data(response_data)
         return g.dash_response
 
+    @with_app_context
     def dispatch(self):
         body = flask.request.get_json()
         g = self._initialize_context(body)
@@ -1871,7 +1881,11 @@ def setup_startup_routes(self) -> None:
         Initialize the startup routes stored in STARTUP_ROUTES.
         """
         for _name, _view_func, _methods in self.STARTUP_ROUTES:
-            self._add_url(f"_dash_startup_route/{_name}", _view_func, _methods)
+            self._add_url(
+                f"_dash_startup_route/{_name}",
+                with_app_context_factory(_view_func, self),
+                _methods,
+            )
         self.STARTUP_ROUTES = []
 
     def _setup_dev_tools(self, **kwargs):

dash/dash.py

@@ -0,0 +1,46 @@
+from dash import (
+    Dash,
+    Input,
+    Output,
+    html,
+    clientside_callback,
+)
+
+
+def test_cmorsnu001_clientside_multiple_output_return_single_no_update(dash_duo):
+    app = Dash(__name__)
+    app.layout = html.Div(
+        [
+            html.Button("trigger", id="trigger-demo"),
+            html.Div("demo1", id="output-demo1"),
+            html.Div("demo2", id="output-demo2"),
+        ],
+        style={"padding": 50},
+    )
+
+    clientside_callback(
+        """(n_clicks) => {
+            try {
+                return window.dash_clientside.no_update;
+            } catch (e) {
+                return [null, null];
+            }
+        }""",
+        Output("output-demo1", "children"),
+        Output("output-demo2", "children"),
+        Input("trigger-demo", "n_clicks"),
+        prevent_initial_call=True,
+    )
+
+    dash_duo.start_server(app)
+
+    trigger_clicker = dash_duo.wait_for_element("#trigger-demo")
+    trigger_clicker.click()
+    dash_duo.wait_for_text_to_equal(
+        "#output-demo1",
+        "demo1",
+    )
+    dash_duo.wait_for_text_to_equal(
+        "#output-demo2",
+        "demo2",
+    )