ensure Variable._repr_html_ works (#3973)

* ensure Variable._repr_html_ works

* added PR 3972 to Bug fixes

* better attribute access

* moved Varible._repr_html_ test to better location

Co-authored-by: Stephan Hoyer <[email protected]>
Co-authored-by: Deepak Cherian <[email protected]>

Author: 3 people

doc/whats-new.rst

@@ -79,6 +79,9 @@ Bug fixes
   By `Tom Nicholas <https://github.com/TomNicholas>`_.
 - Fix ``RasterioDeprecationWarning`` when using a ``vrt`` in ``open_rasterio``. (:issue:`3964`)
   By `Taher Chegini <https://github.com/cheginit>`_.
+- Fix ``AttributeError`` on displaying a :py:class:`Variable`
+  in a notebook context. (:issue:`3972`, :pull:`3973`)
+  By `Ian Castleden <https://github.com/arabidopsis>`_.
 - Fix bug causing :py:meth:`DataArray.interpolate_na` to always drop attributes,
   and added `keep_attrs` argument. (:issue:`3968`)
   By `Tom Nicholas <https://github.com/TomNicholas>`_.

xarray/core/formatting_html.py

@@ -183,7 +183,8 @@ def array_section(obj):
     # "unique" id to expand/collapse the section
     data_id = "section-" + str(uuid.uuid4())
     collapsed = ""
-    preview = escape(inline_variable_array_repr(obj.variable, max_width=70))
+    variable = getattr(obj, "variable", obj)
+    preview = escape(inline_variable_array_repr(variable, max_width=70))
     data_repr = short_data_repr_html(obj)
     data_icon = _icon("icon-database")
 

xarray/tests/test_formatting_html.py

@@ -137,3 +137,15 @@ def test_repr_of_dataset(dataset):
     )
     assert "<U4" in formatted or ">U4" in formatted
     assert "<IA>" in formatted
+
+
+def test_variable_repr_html():
+    v = xr.Variable(["time", "x"], [[1, 2, 3], [4, 5, 6]], {"foo": "bar"})
+    assert hasattr(v, "_repr_html_")
+    with xr.set_options(display_style="html"):
+        html = v._repr_html_().strip()
+    # We don't do a complete string identity since
+    # html output is probably subject to change, is long and... reasons.
+    # Just test that something reasonable was produced.
+    assert html.startswith("<div") and html.endswith("</div>")
+    assert "xarray.Variable" in html