Merge branch 'fix/#931-component-variables-in-network-export' into dev

Author: fwitte

docs/whats_new/v0-9-14.rst

@@ -6,6 +6,9 @@ Bug Fixes
 - When setting a `Ref` for a temperature, the starting value for enthalpy of
   the connection with the `Ref` specified is updated in preprocessing
   (`PR #921 <https://github.com/oemof/tespy/pull/921>`__).
+- When loading a :code:`Network` from its serialized form the :code:`is_var`
+  information of component properties being a variable was missing
+  (`PR #932 <https://github.com/oemof/tespy/pull/932>`__).
 
 Other Changes
 #############

src/tespy/components/component.py

@@ -206,7 +206,7 @@ def set_attr(self, **kwargs):
                     elif isinstance(data, dc_simple):
                         data.set_attr(val=kwargs[key], is_set=True)
 
-                    elif kwargs[key] == 'var' and isinstance(data, dc_cp):
+                    elif kwargs[key] == "var" and isinstance(data, dc_cp):
                         data.set_attr(is_set=True, is_var=True)
 
                     # invalid datatype for keyword

src/tespy/tools/data_containers.py

@@ -697,7 +697,10 @@ def set_unit(self, value):
 
 
 class ComponentProperties(FluidProperties):
-    pass
+
+    def _serialize(self):
+        keys = ["val", "val_SI", "is_set", "unit", "is_var"]
+        return {k: getattr(self, k) for k in keys}
 
 
 class ScalarVariable(DataContainer):

tests/test_networks/test_network.py

@@ -193,6 +193,23 @@ def test_Network_from_dict(self):
         )
         assert imported_nwk.checked, msg
 
+    def test_Network_import_with_component_parameter_as_variable(self):
+        """Test if component variables are retained after import."""
+        pipe = Pipe("pipe")
+        c1 = Connection(self.source, 'out1', pipe, 'in1', label="c1")
+        c2 = Connection(pipe, 'out1', self.sink, 'in1', label="c2")
+        self.nw.add_conns(c1, c2)
+        c1.set_attr(fluid={"H2O": 1}, m=1, T=25, p=2)
+        c2.set_attr(p=1.9)
+        pipe.set_attr(Q=0, D="var", ks=0.00005, L=100)
+        self.nw.solve("design")
+        self.nw.assert_convergence()
+        serialization = self.nw.export()
+        imported_nwk = Network.from_dict(serialization)
+        imported_nwk.solve("design")
+        imported_nwk.assert_convergence()
+        assert approx(pipe.D.val) == imported_nwk.get_comp("pipe").D.val
+
     def test_Network_reader_unknown_component_class(self, tmp_path):
         """Test notsupported component."""
         tmp_path = f"{tmp_path}.json"