Extend to-json conversion to include lazy functions from Django (#408)

* Monkey-patch the dash json conversion to add in lazy evaluation of text for Django

* Collect together patches

* Fix location of module import from string

Co-authored-by: delsim <dev@gibbsconsulting.ca>

Author: delsim

demo/demo/plotly_apps.py

@@ -32,6 +32,7 @@
 import pandas as pd
 
 from django.core.cache import cache
+from django.utils.translation import gettext, gettext_lazy
 
 import dash
 from dash import dcc, html
@@ -46,6 +47,7 @@
 from django_plotly_dash import DjangoDash
 from django_plotly_dash.consumers import send_to_pipe_channel
 
+
 #pylint: disable=too-many-arguments, unused-argument, unused-variable
 
 app = DjangoDash('SimpleExample')
@@ -59,8 +61,8 @@
     html.Div(id='output-color'),
     dcc.RadioItems(
         id='dropdown-size',
-        options=[{'label': i, 'value': j} for i, j in [('L', 'large'),
-                                                       ('M', 'medium'),
+        options=[{'label': i, 'value': j} for i, j in [('L', gettext('large')),
+                                                       ('M', gettext_lazy('medium')),
                                                        ('S', 'small')]],
         value='medium'
     ),

django_plotly_dash/__init__.py

@@ -33,3 +33,4 @@
 # Monkeypatching
 
 import django_plotly_dash._callback
+import django_plotly_dash._patches

django_plotly_dash/_patches.py

@@ -0,0 +1,139 @@
+'''
+Collation of patches made to other python libraries, such as Dash itself.
+
+If/when the patches are not needed they will be removed from this file.
+
+
+Copyright (c) 2022 Gibbs Consulting and others - see CONTRIBUTIONS.md
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+'''
+
+import json
+
+
+from plotly.io._json import config
+from plotly.utils import PlotlyJSONEncoder
+
+from _plotly_utils.optional_imports import get_module
+from django.utils.encoding import force_text
+from django.utils.functional import Promise
+
+
+class DjangoPlotlyJSONEncoder(PlotlyJSONEncoder):
+    """Augment the PlotlyJSONEncoder class with Django delayed processing"""
+    def default(self, obj):
+        if isinstance(obj, Promise):
+            return force_text(obj)
+        return super().default(obj)
+
+
+def to_json_django_plotly(plotly_object, pretty=False, engine=None):
+    """
+    Convert a plotly/Dash object to a JSON string representation
+
+    Parameters
+    ----------
+    plotly_object:
+        A plotly/Dash object represented as a dict, graph_object, or Dash component
+
+    pretty: bool (default False)
+        True if JSON representation should be pretty-printed, False if
+        representation should be as compact as possible.
+
+    engine: str (default None)
+        The JSON encoding engine to use. One of:
+          - "json" for an engine based on the built-in Python json module
+          - "orjson" for a faster engine that requires the orjson package
+          - "auto" for the "orjson" engine if available, otherwise "json"
+        If not specified, the default engine is set to the current value of
+        plotly.io.json.config.default_engine.
+
+    Returns
+    -------
+    str
+        Representation of input object as a JSON string
+
+    See Also
+    --------
+    to_json : Convert a plotly Figure to JSON with validation
+    """
+    orjson = get_module("orjson", should_load=True)
+
+    # Determine json engine
+    if engine is None:
+        engine = config.default_engine
+
+    if engine == "auto":
+        if orjson is not None:
+            engine = "orjson"
+        else:
+            engine = "json"
+    elif engine not in ["orjson", "json"]:
+        raise ValueError("Invalid json engine: %s" % engine)
+
+    modules = {
+        "sage_all": get_module("sage.all", should_load=False),
+        "np": get_module("numpy", should_load=False),
+        "pd": get_module("pandas", should_load=False),
+        "image": get_module("PIL.Image", should_load=False),
+    }
+
+    # Dump to a JSON string and return
+    # --------------------------------
+    if engine == "json":
+        opts = {}
+        if pretty:
+            opts["indent"] = 2
+        else:
+            # Remove all whitespace
+            opts["separators"] = (",", ":")
+
+        return json.dumps(plotly_object, cls=DjangoPlotlyJSONEncoder, **opts)
+    elif engine == "orjson":
+        JsonConfig.validate_orjson()
+        opts = orjson.OPT_NON_STR_KEYS | orjson.OPT_SERIALIZE_NUMPY
+
+        if pretty:
+            opts |= orjson.OPT_INDENT_2
+
+        # Plotly
+        try:
+            plotly_object = plotly_object.to_plotly_json()
+        except AttributeError:
+            pass
+
+        # Try without cleaning
+        try:
+            return orjson.dumps(plotly_object, option=opts).decode("utf8")
+        except TypeError:
+            pass
+
+        cleaned = clean_to_json_compatible(
+            plotly_object,
+            numpy_allowed=True,
+            datetime_allowed=True,
+            modules=modules,
+        )
+        return orjson.dumps(cleaned, option=opts).decode("utf8")
+
+
+import plotly.io.json
+plotly.io.json.to_json_plotly = to_json_django_plotly

django_plotly_dash/dash_wrapper.py

@@ -36,13 +36,12 @@
 from django.urls import reverse
 from django.utils.text import slugify
 from flask import Flask
-from plotly.utils import PlotlyJSONEncoder
 
 from .app_name import app_name, main_view_label
 from .middleware import EmbeddedHolder
 from .util import serve_locally as serve_locally_setting
 from .util import stateless_app_lookup_hook
-from .util import static_asset_path
+from .util import static_asset_path, DjangoPlotlyJSONEncoder
 
 try:
     from dataclasses import dataclass
@@ -480,7 +479,7 @@ def augment_initial_layout(self, base_response, initial_arguments=None):
         reworked_data = self.walk_tree_and_replace(baseData, overrides)
 
         response_data = json.dumps(reworked_data,
-                                   cls=PlotlyJSONEncoder)
+                                   cls=DjangoPlotlyJSONEncoder)
 
         return response_data, base_response.mimetype
 

django_plotly_dash/util.py

@@ -25,10 +25,17 @@
 import json
 import uuid
 
+
+from _plotly_utils.optional_imports import get_module
+
+
 from django.conf import settings
 from django.core.cache import cache
 from django.utils.module_loading import import_string
 
+from django_plotly_dash._patches import DjangoPlotlyJSONEncoder
+
+
 def _get_settings():
     try:
         the_settings = settings.PLOTLY_DASH
@@ -133,3 +140,5 @@ def stateless_app_lookup_hook():
 
     # Default is no additional lookup
     return lambda _: None
+
+