Merge pull request #3765 from i-murray/feature/partial-pattern-matching

Feature: add partial pattern matching (partial=True) for callbacks

Author: T4rk1n

CHANGELOG.md

@@ -5,6 +5,7 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 ## [Unreleased]
 
 ### Added
+- [#3765](https://github.com/plotly/dash/pull/3765) Add opt-in partial pattern matching for callback `Input`, `Output`, and `State` dependencies via `partial_pattern=True`. Dictionary ID patterns can now match component IDs containing additional keys, and partial patterns can be combined with `ALL` and `MATCH` wildcards. Fixes [#3764](https://github.com/plotly/dash/issues/3764).
 - [#3646](https://github.com/plotly/dash/pull/3646) Experimental support for React 19. The default is still React 18.3.1; to use React 19 set the environment variable `REACT_VERSION=19.2.4` before running your app, or call `dash._dash_renderer._set_react_version("19.2.4")` inside the app. React 19 has no official UMD builds, so Dash serves the [`umd-react`](https://www.npmjs.com/package/umd-react) package, together with a compatibility shim loaded after react-dom and before any component package. The shim keeps component libraries built against React <=18 (e.g. dash-bootstrap-components, dash-mantine-components) working under React 19: it stubs the removed `ReactCurrentOwner` internals, redirects the legacy element `$$typeof` symbol so pre-bundled React 18 jsx-runtimes produce elements React 19 accepts (error #525), and exposes a global `react/jsx-runtime` (`window.ReactJSXRuntime`) that Dash's own component bundles externalize to. Component library authors adopting this convention should copy the defensive `jsxRuntimeExternal` webpack external from `components/dash-core-components/webpack.config.js` rather than a bare `'ReactJSXRuntime'` string: it falls back to a `React.createElement`-based runtime when the global is missing, so the same build also works on Dash versions older than this release.
 - [#3925](https://github.com/plotly/dash/pull/3925) Add optional callback request payload compression for server-side callbacks via `compress_payload` and `compress_threshold` callback parameters (default threshold: 5,000 bytes). When enabled and the request body exceeds the threshold, the renderer sends gzip-compressed binary payloads with `Content-Encoding: gzip`, and Dash transparently decompresses on the server (Flask, FastAPI, and Quart). This can significantly reduce callback roundtrip times for large client-to-server payloads. Fixes [#3924](https://github.com/plotly/dash/issues/3924).
 

dash/_callback.py

@@ -349,6 +349,13 @@ def insert_callback(
         "compress_payload": compress_payload,
         "compress_threshold": compress_threshold,
     }
+    # Include output metadata if any output uses partial matching
+    output_list = output if isinstance(output, (list, tuple)) else [output]
+    if any(getattr(o, "partial_pattern", False) for o in output_list):
+        callback_spec["outputs_meta"] = [
+            {"partial": True} if getattr(o, "partial_pattern", False) else {}
+            for o in output_list
+        ]
     if running:
         callback_spec["running"] = running