Refactor JSON encoding to use plotly.py JSON engine (#1514)

* Use plotly.io.json.to_json_plotly for JSON serialization
* Require plotly.py v5
* Run a few tests with both json and orjson encoders
* CHANGELOG entry

CHANGELOG.md

@@ -6,6 +6,11 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ## Dash and Dash Renderer
 
+### Added
+- [#1514](https://github.com/plotly/dash/pull/1514) Perform json encoding using the active plotly JSON engine.  This will default to the faster orjson encoder if the `orjson` package is installed.
+
+
+
 ### Changed
 - [#1707](https://github.com/plotly/dash/pull/1707) Change the default value of the `compress` argument to the `dash.Dash` constructor to `False`. This change reduces CPU usage, and was made in recognition of the fact that many deployment platforms (e.g. Dash Enterprise) already apply their own compression. If deploying to an environment that does not already provide compression, the Dash 1 behavior may be restored by adding `compress=True` to the `dash.Dash` constructor. 
 

dash/_utils.py

@@ -20,6 +20,13 @@
 _strings = (type(""), type(utils.bytes_to_native_str(b"")))
 
 
+def to_json(value):
+    # pylint: disable=import-outside-toplevel
+    from plotly.io.json import to_json_plotly
+
+    return to_json_plotly(value)
+
+
 def interpolate_str(template, **data):
     s = template
     for k, v in data.items():

dash/dash.py

@@ -4,7 +4,6 @@
 import sys
 import collections
 import importlib
-import json
 import pkgutil
 import threading
 import re
@@ -22,8 +21,6 @@
 from werkzeug.debug.tbtools import get_current_traceback
 from pkg_resources import get_distribution, parse_version
 
-import plotly
-
 from .fingerprint import build_fingerprint, check_fingerprint
 from .resources import Scripts, Css
 from .dependencies import (
@@ -49,6 +46,7 @@
     split_callback_id,
     stringify_id,
     strip_relative_path,
+    to_json,
 )
 from . import _dash_renderer
 from . import _validate
@@ -556,7 +554,7 @@ def serve_layout(self):
 
         # TODO - Set browser cache limit - pass hash into frontend
         return flask.Response(
-            json.dumps(layout, cls=plotly.utils.PlotlyJSONEncoder),
+            to_json(layout),
             mimetype="application/json",
         )
 
@@ -714,7 +712,7 @@ def _generate_scripts_html(self):
 
     def _generate_config_html(self):
         return '<script id="_dash-config" type="application/json">{}</script>'.format(
-            json.dumps(self._config(), cls=plotly.utils.PlotlyJSONEncoder)
+            to_json(self._config())
         )
 
     def _generate_renderer(self):
@@ -1109,9 +1107,7 @@ def add_context(*args, **kwargs):
                 response = {"response": component_ids, "multi": True}
 
                 try:
-                    jsonResponse = json.dumps(
-                        response, cls=plotly.utils.PlotlyJSONEncoder
-                    )
+                    jsonResponse = to_json(response)
                 except TypeError:
                     _validate.fail_callback_output(output_value, output)
 

requires-dev.txt

@@ -10,3 +10,5 @@ black==21.6b0
 fire==0.4.0
 coloredlogs==15.0.1
 flask-talisman==0.8.1
+orjson==3.3.1;python_version<"3.7"
+orjson==3.6.1;python_version>="3.7"

requires-install.txt

@@ -1,6 +1,6 @@
 Flask>=1.0.4
 flask-compress
-plotly
+plotly>=5.0.0
 dash-core-components==1.17.1
 dash-html-components==1.1.4
 dash-table==4.12.0

tests/integration/callbacks/test_basic_callback.py

@@ -16,6 +16,7 @@
 from dash.dependencies import Input, Output, State
 from dash.exceptions import PreventUpdate
 from dash.testing import wait
+from tests.integration.utils import json_engine
 
 
 def test_cbsc001_simple_callback(dash_duo):
@@ -248,57 +249,61 @@ def update_out2(n_clicks, data):
     assert dash_duo.get_logs() == []
 
 
-def test_cbsc005_children_types(dash_duo):
-    app = dash.Dash()
-    app.layout = html.Div([html.Button(id="btn"), html.Div("init", id="out")])
-
-    outputs = [
-        [None, ""],
-        ["a string", "a string"],
-        [123, "123"],
-        [123.45, "123.45"],
-        [[6, 7, 8], "678"],
-        [["a", "list", "of", "strings"], "alistofstrings"],
-        [["strings", 2, "numbers"], "strings2numbers"],
-        [["a string", html.Div("and a div")], "a string\nand a div"],
-    ]
-
-    @app.callback(Output("out", "children"), [Input("btn", "n_clicks")])
-    def set_children(n):
-        if n is None or n > len(outputs):
-            return dash.no_update
-        return outputs[n - 1][0]
+@pytest.mark.parametrize("engine", ["json", "orjson"])
+def test_cbsc005_children_types(dash_duo, engine):
+    with json_engine(engine):
+        app = dash.Dash()
+        app.layout = html.Div([html.Button(id="btn"), html.Div("init", id="out")])
+
+        outputs = [
+            [None, ""],
+            ["a string", "a string"],
+            [123, "123"],
+            [123.45, "123.45"],
+            [[6, 7, 8], "678"],
+            [["a", "list", "of", "strings"], "alistofstrings"],
+            [["strings", 2, "numbers"], "strings2numbers"],
+            [["a string", html.Div("and a div")], "a string\nand a div"],
+        ]
 
-    dash_duo.start_server(app)
-    dash_duo.wait_for_text_to_equal("#out", "init")
+        @app.callback(Output("out", "children"), [Input("btn", "n_clicks")])
+        def set_children(n):
+            if n is None or n > len(outputs):
+                return dash.no_update
+            return outputs[n - 1][0]
 
-    for children, text in outputs:
-        dash_duo.find_element("#btn").click()
-        dash_duo.wait_for_text_to_equal("#out", text)
+        dash_duo.start_server(app)
+        dash_duo.wait_for_text_to_equal("#out", "init")
 
+        for children, text in outputs:
+            dash_duo.find_element("#btn").click()
+            dash_duo.wait_for_text_to_equal("#out", text)
 
-def test_cbsc006_array_of_objects(dash_duo):
-    app = dash.Dash()
-    app.layout = html.Div(
-        [html.Button(id="btn"), dcc.Dropdown(id="dd"), html.Div(id="out")]
-    )
 
-    @app.callback(Output("dd", "options"), [Input("btn", "n_clicks")])
-    def set_options(n):
-        return [{"label": "opt{}".format(i), "value": i} for i in range(n or 0)]
+@pytest.mark.parametrize("engine", ["json", "orjson"])
+def test_cbsc006_array_of_objects(dash_duo, engine):
+    with json_engine(engine):
+        app = dash.Dash()
+        app.layout = html.Div(
+            [html.Button(id="btn"), dcc.Dropdown(id="dd"), html.Div(id="out")]
+        )
 
-    @app.callback(Output("out", "children"), [Input("dd", "options")])
-    def set_out(opts):
-        print(repr(opts))
-        return len(opts)
+        @app.callback(Output("dd", "options"), [Input("btn", "n_clicks")])
+        def set_options(n):
+            return [{"label": "opt{}".format(i), "value": i} for i in range(n or 0)]
 
-    dash_duo.start_server(app)
+        @app.callback(Output("out", "children"), [Input("dd", "options")])
+        def set_out(opts):
+            print(repr(opts))
+            return len(opts)
 
-    dash_duo.wait_for_text_to_equal("#out", "0")
-    for i in range(5):
-        dash_duo.find_element("#btn").click()
-        dash_duo.wait_for_text_to_equal("#out", str(i + 1))
-        dash_duo.select_dcc_dropdown("#dd", "opt{}".format(i))
+        dash_duo.start_server(app)
+
+        dash_duo.wait_for_text_to_equal("#out", "0")
+        for i in range(5):
+            dash_duo.find_element("#btn").click()
+            dash_duo.wait_for_text_to_equal("#out", str(i + 1))
+            dash_duo.select_dcc_dropdown("#dd", "opt{}".format(i))
 
 
 @pytest.mark.parametrize("refresh", [False, True])

tests/integration/callbacks/test_malformed_request.py

@@ -33,7 +33,7 @@ def update_output(value):
         ),
     )
     assert response.status_code == 200
-    assert '"o1": {"children": 9}' in response.text
+    assert '"o1":{"children":9}' in response.text
 
     # now some bad ones
     outspecs = [

tests/integration/utils.py

@@ -1,4 +1,5 @@
 import time
+import contextlib
 
 
 TIMEOUT = 5  # Seconds
@@ -61,3 +62,15 @@ def wrapped_condition_function():
         time.sleep(0.5)
 
     raise WaitForTimeout(get_message())
+
+
+@contextlib.contextmanager
+def json_engine(engine):
+    import plotly.io as pio
+
+    original_engine = pio.json.config.default_engine
+    try:
+        pio.json.config.default_engine = engine
+        yield
+    finally:
+        pio.json.config.default_engine = original_engine