Add set serialisation & check for lists in attrs

src/calliope/core/io.py

@@ -37,12 +37,9 @@ def read_netcdf(path):
                     calliope_version, __version__
                 )
             )
-    for attr in _pop_serialised_list(model_data.attrs, "serialised_dicts"):
-        model_data.attrs[attr] = AttrDict.from_yaml_string(model_data.attrs[attr])
-    for attr in _pop_serialised_list(model_data.attrs, "serialised_bools"):
-        model_data.attrs[attr] = bool(model_data.attrs[attr])
-    for attr in _pop_serialised_list(model_data.attrs, "serialised_nones"):
-        model_data.attrs[attr] = None
+    _deserialise(model_data.attrs)
+    for var in model_data.data_vars.values():
+        _deserialise(var.attrs)
 
     # Convert empty strings back to np.NaN
     # TODO: revert when this issue is solved: https://github.com/pydata/xarray/issues/1647
@@ -58,17 +55,82 @@ def read_netcdf(path):
     return model_data
 
 
-def _pop_serialised_list(attribute_dict, serialised_items):
-    serialised_ = attribute_dict.pop(serialised_items, [])
+def _pop_serialised_list(
+    attrs: dict, serialised_items: Union[str, list, np.ndarray]
+) -> Union[list, np.ndarray]:
+    serialised_ = attrs.pop(serialised_items, [])
     if not isinstance(serialised_, (list, np.ndarray)):
         return [serialised_]
     else:
         return serialised_
 
 
+def _serialise(attrs: dict) -> None:
+    """Convert troublesome datatypes to nicer ones in xarray attribute dictionaries.
+
+    This will tackle dictionaries (to string), booleans (to int), None (to string), and sets (to list).
+
+    Args:
+        attrs (dict):
+            Attribute dictionary from an xarray Dataset/DataArray.
+            Changes will be made in-place, so be sure to supply a copy of your dictionary if you want access to its original state.
+    """
+    # Convert dicts attrs to yaml strings
+    dict_attrs = [k for k, v in attrs.items() if isinstance(v, dict)]
+    attrs["serialised_dicts"] = dict_attrs
+    for attr in dict_attrs:
+        attrs[attr] = AttrDict(attrs[attr]).to_yaml()
+
+    # Convert boolean attrs to ints
+    bool_attrs = [k for k, v in attrs.items() if isinstance(v, bool)]
+    attrs["serialised_bools"] = bool_attrs
+    for attr in bool_attrs:
+        attrs[attr] = int(attrs[attr])
+
+    # Convert None attrs to 'None'
+    none_attrs = [k for k, v in attrs.items() if v is None]
+    attrs["serialised_nones"] = none_attrs
+    for attr in none_attrs:
+        attrs[attr] = "None"
+
+    # Convert set attrs to lists
+    set_attrs = [k for k, v in attrs.items() if isinstance(v, set)]
+    for attr in set_attrs:
+        attrs[attr] = list(attrs[attr])
+
+    list_attrs = [k for k, v in attrs.items() if isinstance(v, list)]
+    for attr in list_attrs:
+        if any(not isinstance(i, str) for i in attrs[attr]):
+            raise TypeError(
+                f"Cannot serialise a sequence of values stored in a model attribute unless all values are strings, found: {attrs[attr]}"
+            )
+    else:
+        attrs["serialised_sets"] = set_attrs
+
+
+def _deserialise(attrs: dict) -> None:
+    """Convert troublesome datatypes in xarray attribute dictionaries from their stored data type to the data types expected by Calliope.
+
+    This will tackle dictionaries (from string), booleans (from int), None (form string), and sets (from list).
+
+    Args:
+        attrs (dict):
+            Attribute dictionary from an xarray Dataset/DataArray.
+            Changes will be made in-place, so be sure to supply a copy of your dictionary if you want access to its original state.
+    """
+    for attr in _pop_serialised_list(attrs, "serialised_dicts"):
+        attrs[attr] = AttrDict.from_yaml_string(attrs[attr])
+    for attr in _pop_serialised_list(attrs, "serialised_bools"):
+        attrs[attr] = bool(attrs[attr])
+    for attr in _pop_serialised_list(attrs, "serialised_nones"):
+        attrs[attr] = None
+    for attr in _pop_serialised_list(attrs, "serialised_sets"):
+        attrs[attr] = set(attrs[attr])
+
+
 def save_netcdf(model_data, path, model=None):
     original_model_data_attrs = model_data.attrs
-    model_data_attrs = model_data.attrs.copy()
+    model_data_attrs = original_model_data_attrs.copy()
 
     if model is not None and hasattr(model, "_model_run"):
         # Attach _model_run and _debug_data to _model_data
@@ -79,23 +141,9 @@ def save_netcdf(model_data, path, model=None):
         if hasattr(model, "_debug_data"):
             model_data_attrs["_debug_data"] = model._debug_data.to_yaml()
 
-    # Convert dicts attrs to yaml strings
-    dict_attrs = [k for k, v in model_data_attrs.items() if isinstance(v, dict)]
-    model_data_attrs["serialised_dicts"] = dict_attrs
-    for k in dict_attrs:
-        model_data_attrs[k] = AttrDict(model_data_attrs[k]).to_yaml()
-
-    # Convert boolean attrs to ints
-    bool_attrs = [k for k, v in model_data_attrs.items() if isinstance(v, bool)]
-    model_data_attrs["serialised_bools"] = bool_attrs
-    for k in bool_attrs:
-        model_data_attrs[k] = int(model_data_attrs[k])
-
-    # Convert None attrs to 'None'
-    none_attrs = [k for k, v in model_data_attrs.items() if v is None]
-    model_data_attrs["serialised_nones"] = none_attrs
-    for k in none_attrs:
-        model_data_attrs[k] = "None"
+    _serialise(model_data_attrs)
+    for var in model_data.data_vars.values():
+        _serialise(var.attrs)
 
     encoding = {
         k: {"zlib": False, "_FillValue": None}
@@ -110,6 +158,8 @@ def save_netcdf(model_data, path, model=None):
         model_data.close()  # Force-close NetCDF file after writing
     finally:  # Revert model_data.attrs back
         model_data.attrs = original_model_data_attrs
+        for var in model_data.data_vars.values():
+            _deserialise(var.attrs)
 
 
 def save_csv(model_data, path, dropna=True):

tests/test_io.py

@@ -5,21 +5,33 @@
 import pytest  # noqa: F401
 import xarray as xr
 from calliope import exceptions
+from calliope.core import io
+from calliope.test.common.util import check_error_or_warning
 
 
 class TestIO:
     @pytest.fixture(scope="module")
-    def model(self):
+    def vars_to_add_attrs(self):
+        return ["resource", "energy_cap"]
+
+    @pytest.fixture(scope="module")
+    def model(self, vars_to_add_attrs):
         model = calliope.examples.national_scale()
-        model._model_data = model._model_data.assign_attrs(
-            foo_true=True,
-            foo_false=False,
-            foo_none=None,
-            foo_dict={"foo": {"a": 1}},
-            foo_attrdict=calliope.AttrDict({"foo": {"a": 1}}),
-        )
+        attrs = {
+            "foo_true": True,
+            "foo_false": False,
+            "foo_none": None,
+            "foo_dict": {"foo": {"a": 1}},
+            "foo_attrdict": calliope.AttrDict({"foo": {"a": 1}}),
+            "foo_set": set(["foo", "bar"]),
+        }
+        model._model_data = model._model_data.assign_attrs(**attrs)
         model.build()
         model.solve()
+
+        for var in vars_to_add_attrs:
+            model._model_data[var] = model._model_data[var].assign_attrs(**attrs)
+
         return model
 
     @pytest.fixture(scope="module")
@@ -53,31 +65,33 @@ def test_save_netcdf(self, model_file):
             ("foo_none", type(None), None),
             ("foo_dict", dict, {"foo": {"a": 1}}),
             ("foo_attrdict", calliope.AttrDict, calliope.AttrDict({"foo": {"a": 1}})),
+            ("foo_set", set, set(["foo", "bar"])),
         ],
     )
     @pytest.mark.parametrize("model_name", ["model", "model_from_file"])
     def test_serialised_attrs(
-        self, request, attr, expected_type, expected_val, model_name
+        self, request, attr, expected_type, expected_val, model_name, vars_to_add_attrs
     ):
         model = request.getfixturevalue(model_name)
-        # Ensure that boolean attrs have not changed
-
-        assert isinstance(model._model_data.attrs[attr], expected_type)
-        if expected_val is None:
-            assert model._model_data.attrs[attr] is None
-        else:
-            assert model._model_data.attrs[attr] == expected_val
+        var_attrs = [model._model_data[var].attrs for var in vars_to_add_attrs]
+        for attrs in [model._model_data.attrs, *var_attrs]:
+            assert isinstance(attrs[attr], expected_type)
+            if expected_val is None:
+                assert attrs[attr] is None
+            else:
+                assert attrs[attr] == expected_val
 
     @pytest.mark.parametrize(
-        "serialised_list", ["serialised_bools", "serialised_nones", "serialised_dicts"]
+        "serialised_list",
+        ["serialised_bools", "serialised_nones", "serialised_dicts", "serialised_sets"],
     )
     @pytest.mark.parametrize("model_name", ["model", "model_from_file"])
     def test_serialised_list_popped(self, request, serialised_list, model_name):
         model = request.getfixturevalue(model_name)
         assert serialised_list not in model._model_data.attrs.keys()
 
     @pytest.mark.parametrize(
-        ["serialised_list", "list_elements"],
+        ["serialisation_list_name", "list_elements"],
         [
             ("serialised_bools", ["foo_true", "foo_false"]),
             ("serialised_nones", ["foo_none", "scenario"]),
@@ -92,14 +106,27 @@ def test_serialised_list_popped(self, request, serialised_list, model_name):
                     "math",
                 ],
             ),
+            ("serialised_sets", ["foo_set"]),
         ],
     )
-    def test_serialised_list(
-        self, model_from_file_no_processing, serialised_list, list_elements
+    def test_serialisation_lists(
+        self, model_from_file_no_processing, serialisation_list_name, list_elements
     ):
-        assert not set(
-            model_from_file_no_processing.attrs[serialised_list]
-        ).symmetric_difference(list_elements)
+        serialisation_list = io._pop_serialised_list(
+            model_from_file_no_processing.attrs, serialisation_list_name
+        )
+        assert not set(serialisation_list).symmetric_difference(list_elements)
+
+    @pytest.mark.parametrize(
+        "attrs", [{"foo": [1]}, {"foo": [None]}, {"foo": [1, "bar"]}, {"foo": set([1])}]
+    )
+    def test_non_strings_in_serialised_lists(self, attrs):
+        with pytest.raises(TypeError) as excinfo:
+            io._serialise(attrs)
+        assert check_error_or_warning(
+            excinfo,
+            f"Cannot serialise a sequence of values stored in a model attribute unless all values are strings, found: {attrs['foo']}",
+        )
 
     def test_save_csv_dir_mustnt_exist(self, model):
         with tempfile.TemporaryDirectory() as tempdir: