io: fix netcdf IO for parameters

doc/release_notes.rst

@@ -4,6 +4,7 @@ Release Notes
 Upcoming Version
 ----------------
 
+* The writing and reading from netcdf files was fixed to correctly handle the model `parameters` field.
 
 Version 0.3.10
 --------------

linopy/io.py

@@ -918,7 +918,7 @@ def with_prefix(ds, prefix):
     if m.objective.value is not None:
         objective = objective.assign_attrs(value=m.objective.value)
     obj = [with_prefix(objective, "objective")]
-    params = [with_prefix(m.parameters, "params")]
+    params = [with_prefix(m.parameters, "parameters")]
 
     scalars = {k: getattr(m, k) for k in m.scalar_attrs}
     ds = xr.merge(vars + cons + obj + params, combine_attrs="drop_conflicts")
@@ -1008,7 +1008,7 @@ def get_prefix(ds, prefix):
     m.objective.sense = objective.attrs.pop("sense")
     m.objective._value = objective.attrs.pop("value", None)
 
-    m.parameters = get_prefix(ds, "parameter")
+    m.parameters = get_prefix(ds, "parameters")
 
     for k in m.scalar_attrs:
         setattr(m, k, ds.attrs.get(k))

test/test_io.py

@@ -25,6 +25,8 @@ def model():
 
     m.add_objective(2 * x + 3 * y)
 
+    m.parameters["param"] = xr.DataArray([1, 2, 3, 4], dims=["x"])
+
     return m