Fix callback output of ndarray and no_update check.

CHANGELOG.md

@@ -4,6 +4,9 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [UNRELEASED]
 
+### Fixed
+
+- [#2175](https://github.com/plotly/dash/pull/2175) Fix [#2173](https://github.com/plotly/dash/issues/2173) callback output of ndarray and no_update check.
 - [#2146](https://github.com/plotly/dash/pull/2146) Remove leftover debug console.log statement.
 - [#2168](https://github.com/plotly/dash/pull/2168)  Reverts [#2126](https://github.com/plotly/dash/pull/2126) (supporting redirect from root when using pages) until the new bugs introduced by that PR are fixed.
 

dash/_callback.py

@@ -40,9 +40,9 @@ def to_plotly_json(self):  # pylint: disable=no-self-use
 
     @staticmethod
     def is_no_update(obj):
-        return isinstance(obj, NoUpdate) or obj == {
-            "_dash_no_update": "_dash_no_update"
-        }
+        return isinstance(obj, NoUpdate) or (
+            isinstance(obj, dict) and obj == {"_dash_no_update": "_dash_no_update"}
+        )
 
 
 GLOBAL_CALLBACK_LIST = []

tests/integration/callbacks/test_basic_callback.py

@@ -4,6 +4,7 @@
 import pytest
 import time
 
+import numpy as np
 import werkzeug
 
 from dash_test_components import (
@@ -765,3 +766,19 @@ def update_output(value):
         return f"returning {value}"
 
     assert update_output("my-value") == "returning my-value"
+
+
+def test_cbsc018_callback_ndarray_output(dash_duo):
+    app = Dash(__name__)
+    app.layout = html.Div([dcc.Store(id="output"), html.Button("click", id="clicker")])
+
+    @app.callback(
+        Output("output", "data"),
+        Input("clicker", "n_clicks"),
+    )
+    def on_click(_):
+        return np.array([[1, 2, 3], [4, 5, 6]], np.int32)
+
+    dash_duo.start_server(app)
+
+    assert dash_duo.get_logs() == []