Fix bugs in JSON serialization (#291)

Found and fixed the following bugs:
- Fix version checks in `network_from_dict`
- Emit proper warning for older versions
- Add missing `max_loading` for lines
- Add missing `max_loading` for transformers
- Add missing `tap` for transformers
- Fix error due to sorting of line parameters and transformer parameters
  with heterogeneous ID types
- Fix conversion of `single` and `center` transformer types to proper
  vector groups
- Fix upgrading of `max_current`, `conductor_type`, and `insulator_type`
  of line parameters

These bugs were found with testing more comprehensive JSON files.
Added files for all JSON versions and the corresponding file generator
scripts.

Also added a test to ensure these files do not get modified by mistake
when refactoring the code base.

doc/Changelog.md

@@ -19,6 +19,7 @@ og:description: See what's new in the latest release of Roseau Load Flow !
 
 ## Unreleased
 
+- {gh-pr}`291` Fixed several bugs in JSON serialization and deserialization.
 - {gh-pr}`289` Improve the `TransformerParameters` class and the transformers catalogue
 
   - Add 15kV transformers to the catalogue (SE and FT)

roseau/load_flow/io/dict.py

@@ -95,16 +95,18 @@ def network_from_dict(  # noqa: C901
 
     version = data.get("version", 0)
     if version <= 2:
-        logger.warning(
+        warnings.warn(
             f"Got an outdated network file (version {version}), trying to update to the current format "
-            f"(version {NETWORK_JSON_VERSION}). Please save the network again."
+            f"(version {NETWORK_JSON_VERSION}). Please save the network again.",
+            category=UserWarning,
+            stacklevel=find_stack_level(),
         )
-        if version == 0:
+        if version <= 0:
             data = v0_to_v1_converter(data)
             include_results = False  # V0 network dictionaries didn't have results
-        if version == 1:
+        if version <= 1:
             data = v1_to_v2_converter(data)
-        if version == 2:
+        if version <= 2:
             data = v2_to_v3_converter(data)
     else:
         # If we arrive here, we dealt with all legacy versions, it must be the current one
@@ -177,11 +179,20 @@ def network_from_dict(  # noqa: C901
         bus2 = buses[line_data["bus2"]]
         geometry = Line._parse_geometry(line_data.get("geometry"))
         length = line_data["length"]
+        max_loading = line_data["max_loading"]
         lp = lines_params[line_data["params_id"]]
         gid = line_data.get("ground")
         ground = grounds[gid] if gid is not None else None
         line = Line(
-            id=id, bus1=bus1, bus2=bus2, parameters=lp, phases=phases, length=length, ground=ground, geometry=geometry
+            id=id,
+            bus1=bus1,
+            bus2=bus2,
+            parameters=lp,
+            phases=phases,
+            length=length,
+            ground=ground,
+            geometry=geometry,
+            max_loading=max_loading,
         )
         if include_results:
             line = _assign_branch_currents(branch=line, branch_data=line_data)
@@ -195,12 +206,22 @@ def network_from_dict(  # noqa: C901
         id = transformer_data["id"]
         phases1 = transformer_data["phases1"]
         phases2 = transformer_data["phases2"]
+        tap = transformer_data["tap"]
+        max_loading = transformer_data["max_loading"]
         bus1 = buses[transformer_data["bus1"]]
         bus2 = buses[transformer_data["bus2"]]
         geometry = Transformer._parse_geometry(transformer_data.get("geometry"))
         tp = transformers_params[transformer_data["params_id"]]
         transformer = Transformer(
-            id=id, bus1=bus1, bus2=bus2, parameters=tp, phases1=phases1, phases2=phases2, geometry=geometry
+            id=id,
+            bus1=bus1,
+            bus2=bus2,
+            parameters=tp,
+            phases1=phases1,
+            phases2=phases2,
+            tap=tap,
+            geometry=geometry,
+            max_loading=max_loading,
         )
         if include_results:
             transformer = _assign_branch_currents(branch=transformer, branch_data=transformer_data)
@@ -302,13 +323,13 @@ def network_to_dict(en: "ElectricalNetwork", *, include_results: bool) -> JsonDi
     line_params: list[JsonDict] = []
     for lp in lines_params_dict.values():
         line_params.append(lp.to_dict(include_results=include_results))
-    line_params.sort(key=lambda x: x["id"])  # Always keep the same order
+    line_params.sort(key=lambda x: (type(x["id"]).__name__, str(x["id"])))  # Always keep the same order
 
     # Transformer parameters
     transformer_params: list[JsonDict] = []
     for tp in transformers_params_dict.values():
         transformer_params.append(tp.to_dict(include_results=include_results))
-    transformer_params.sort(key=lambda x: x["id"])  # Always keep the same order
+    transformer_params.sort(key=lambda x: (type(x["id"]).__name__, str(x["id"])))  # Always keep the same order
 
     res = {
         "version": NETWORK_JSON_VERSION,
@@ -629,7 +650,7 @@ def v1_to_v2_converter(data: JsonDict) -> JsonDict:
     return results
 
 
-def v2_to_v3_converter(data: JsonDict) -> JsonDict:
+def v2_to_v3_converter(data: JsonDict) -> JsonDict:  # noqa: C901
     """Convert a v2 network dict to a v3 network dict.
 
     Args:
@@ -663,9 +684,17 @@ def v2_to_v3_converter(data: JsonDict) -> JsonDict:
     transformers_params = []
     transformers_params_max_loading = {}
     for transformer_param_data in old_transformers_params:
-        transformer_param_data["vg"] = transformer_param_data.pop("type")
+        vg = transformer_param_data.pop("type")
+        if vg == "single":
+            vg = "Ii0"
+        elif vg == "center":
+            vg = "Iii0"
+        transformer_param_data["vg"] = vg
         if (max_power := transformer_param_data.pop("max_power", None)) is not None:
-            transformers_params_max_loading[transformer_param_data["id"]] = max_power / transformer_param_data["sn"]
+            loading = max_power / transformer_param_data["sn"]
+        else:
+            loading = 1
+        transformers_params_max_loading[transformer_param_data["id"]] = loading
         transformers_params.append(transformer_param_data)
 
     # Rename `maximal_current` in `ampacities` and uses array
@@ -676,14 +705,14 @@ def v2_to_v3_converter(data: JsonDict) -> JsonDict:
     lines_params = []
     for line_param_data in old_lines_params:
         size = len(line_param_data["z_line"][0])
-        if (maximal_current := line_param_data.pop("maximal_current", None)) is not None:
+        if (maximal_current := line_param_data.pop("max_current", None)) is not None:
             line_param_data["ampacities"] = [maximal_current] * size
         if (section := line_param_data.pop("section", None)) is not None:
             line_param_data["sections"] = [section] * size
-        if (conductor_type := line_param_data.pop("conductor_types", None)) is not None:
+        if (conductor_type := line_param_data.pop("conductor_type", None)) is not None:
             line_param_data["materials"] = [conductor_type] * size
         if (
-            (insulator_type := line_param_data.pop("insulator_types", None)) is not None
+            (insulator_type := line_param_data.pop("insulator_type", None)) is not None
         ) and insulator_type.lower() != "unknown":
             line_param_data["insulators"] = [insulator_type] * size
         lines_params.append(line_param_data)
@@ -699,7 +728,7 @@ def v2_to_v3_converter(data: JsonDict) -> JsonDict:
     old_transformers = data.get("transformers", [])
     transformers = []
     for transformer_data in old_transformers:
-        transformer_data["max_loading"] = transformers_params_max_loading.get(transformer_data["params_id"], 1)
+        transformer_data["max_loading"] = transformers_params_max_loading[transformer_data["params_id"]]
         transformers.append(transformer_data)
 
     results = {

roseau/load_flow/io/tests/data/README.md

@@ -0,0 +1,13 @@
+# Versioned network JSON files for testing
+
+## JSON files
+
+**DO NOT MODIFY** the JSON files in this directory if the tests fail. Adapt the converter functions
+in the `roseau.load_flow.io.dict` module instead.
+
+## Generator scripts
+
+Scripts in the _generators_ directory are used to generate the versioned network JSON files. They
+are executed using old versions of rlf.
+
+**DO NOT UPGRADE** these scripts when modifying rlf.