Add support for specifying fig.data as a scalar trace.

Author: jonmmease

packages/python/plotly/_plotly_utils/basevalidators.py

@@ -2268,6 +2268,8 @@ def description(self):
     that may be specified as:
       - A list or tuple of trace instances
         (e.g. [Scatter(...), Bar(...)])
+      - A single trace instance
+        (e.g. Scatter(...), Bar(...), etc.)
       - A list or tuple of dicts of string/value properties where:
         - The 'type' property specifies the trace type
 {trace_types}
@@ -2302,7 +2304,10 @@ def validate_coerce(self, v, skip_invalid=False):
 
         if v is None:
             v = []
-        elif isinstance(v, (list, tuple)):
+        else:
+            if not isinstance(v, (list, tuple)):
+                v = [v]
+
             trace_classes = tuple(self.class_map.values())
 
             res = []
@@ -2355,12 +2360,6 @@ def validate_coerce(self, v, skip_invalid=False):
                 for trace in v:
                     trace.uid = str(uuid.uuid4())
 
-        else:
-            if skip_invalid:
-                v = []
-            else:
-                self.raise_invalid_val(v)
-
         return v
 
 

packages/python/plotly/plotly/tests/test_core/test_graph_objs/test_figure.py

@@ -139,3 +139,10 @@ def test_add_trace_underscore_kwarg(self):
         fig.add_scatter(y=[2, 1, 3], marker_line_color='green')
 
         self.assertEqual(fig.data[0].marker.line.color, 'green')
+
+    def test_scalar_trace_as_data(self):
+        fig = go.Figure(data=go.Waterfall(y=[2, 1, 3]))
+        self.assertEqual(fig.data, (go.Waterfall(y=[2, 1, 3]),))
+
+        fig = go.Figure(data=dict(type='waterfall', y=[2, 1, 3]))
+        self.assertEqual(fig.data, (go.Waterfall(y=[2, 1, 3]),))