PX templates should override, not merge into default

plotly · nicolaskruchten · Nov 5, 2019 · Nov 5, 2019 · Nov 5, 2019 · 2eba10086983635598e751cdf1c284045b3dba4b
commit 2eba10086983635598e751cdf1c284045b3dba4b
diff --git a/packages/python/plotly/plotly/express/_core.py b/packages/python/plotly/plotly/express/_core.py
@@ -1264,7 +1264,7 @@ def make_figure(args, constructor, trace_patch={}, layout_patch={}):
            cmax=range_color[1],
            colorbar=dict(title=get_decorated_label(args, args[colorvar], colorvar)),
        )
-    for v in ["title", "height", "width", "template"]:
+    for v in ["title", "height", "width"]:
        if args[v]:
            layout_patch[v] = args[v]
    layout_patch["legend"] = {"tracegroupgap": 0}
@@ -1295,6 +1295,9 @@ def make_figure(args, constructor, trace_patch={}, layout_patch={}):
    # Add traces, layout and frames to figure
    fig.add_traces(frame_list[0]["data"] if len(frame_list) > 0 else [])
    fig.layout.update(layout_patch)
+     if "template" in args and args["template"] is not None:
+        fig.update_layout(template=args["template"], overwrite=True)
+
    fig.frames = frame_list if len(frames) > 1 else []

    fig._px_trendlines = pd.DataFrame(trendline_rows)

diff --git a/test/percy/plotly-express.py b/test/percy/plotly-express.py
@@ -470,3 +470,13 @@
    range_color=[20, 80],
 )
 fig.write_html(os.path.join(dir_name, "choropleth.html"), auto_play=False)
+
+### test template overriding (should be white background, courier font)
+
+import plotly.express as px
+
+iris = px.data.iris()
+fig = px.scatter(
+    iris, x="sepal_width", y="sepal_length", template=dict(layout_font_family="Courier")
+)
+fig.write_html(os.path.join(dir_name, "scatter.html"))